Explaining temporal qualia


European Journal for Philosophy of Science
https://doi.org/10.1007/s13194-019-0264-6

PAPER IN GENERAL PHILOSOPHY OF SCIENCE

Explaining temporal qualia

Matt Farr1

Received: 4 March 2019 / Accepted: 26 September 2019 /
© The Author(s) 2020

Abstract
Experiences of motion and change are widely taken to have a ‘flow-like’ quality.
Call this ‘temporal qualia’. Temporal qualia are commonly thought to be central
to the question of whether time objectively passes: (1) passage realists take tempo-
ral passage to be necessary in order for us to have the temporal qualia we do; (2)
passage antirealists typically concede that time appears to pass, as though our tem-
poral qualia falsely represent time as passing. I reject both claims and make the case
that passage-talk plays no useful explanatory role with respect to temporal qualia,
but rather obfuscates what the philosophical problem of temporal qualia is. I offer a
‘reductionist’ account of temporal qualia that makes no reference to the concept of
passage and argue that it is well motivated by empirical studies in motion perception.

Keywords Time · Temporal passage · Temporal experience · Motion perception ·
Cognitive illusions

1 Introduction

There is a supposed ‘flow-like’ element of our experience of things like motion and
change that is commonly understood as an appearance or representation of time pass-
ing. To point to some token examples from the literature: Norton (2010 p. 24) holds
that ‘the passage of time is one of our most powerful experiences’; Davies (1996,
p. 275) takes the ‘sensation of a flowing time’ to be ‘basic to my experience of the
world’; and Le Poidevin (2007, p. 76) suggests that ‘we just see time passing in front
of us, in [...] any motion or change at all’. The idea of the passage or flow of time
being given in experience is widespread but rarely expressed in terms that go beyond

� Matt Farr
mail@mattfarr.co.uk

1 Department of History and Philosophy of Science & Trinity College, University of Cambridge,
Cambridge, UK

(2020) 10: 8

JPublished online: 9 anuary 2020

http://crossmark.crossref.org/dialog/?doi=10.1007/s13194-019-0264-6&domain=pdf
http://orcid.org/0000-0001-6238-7990
mailto: mail@mattfarr.co.uk


suggestive metaphors. Nonetheless, it is common even for antirealists about the pas-
sage of time—those who deny that the passage of time is a fundamental feature of
the world above and beyond the temporal aspects of our experience—to nonethe-
less concede that time appears to pass, such that our temporal experience constitutes
an illusion in this respect. Call this idea ‘illusionism’. Much contemporary litera-
ture in philosophy of time is devoted to providing a positive account of illusionism
by explaining how and why time appears to pass. This has involved a recent focus
on appeals to cognitive science, particularly the various empirical studies of motion
perception, to explain why time appears to pass.1

This project is based on a mistake. There are two independently legitimate
philosophical problems here that if run together serve to create basic confusions
concerning each: (1) the ontological question of whether time really passes, indepen-
dently of our experience; and (2) how to explain the phenomenal character of our
temporal experience, particularly our perception of things like change and motion,
in light of the relevant research in cognitive science (time perception illusions, psy-
chophysics experiments, fMRI scans, etc.). Call (1) the problem of temporal passage,
and (2) the problem of temporal qualia. There is no doubt that there is something it
is like to perceive movement and change, and this is ubiquitously compared to the
idea of time itself flowing like a river or passing by like an object. The central argu-
ment of this paper is that not only is such a concept of temporal passage not needed
to explain temporal qualia, but that it is wholly irrelevant to temporal experience in
general and has actively distorted both what the problem of temporal qualia has been
taken to be, and also what kind of a philosophical problem the debate about temporal
passage poses. The contention of the paper is normative: the problems of temporal
passage and temporal qualia should be kept separate; and temporal qualia should be
explained in passage-free terms.

The paper is structured as follows. Section 2 sets the terms for the paper by separat-
ing the problem of temporal passage from the problem of temporal qualia. Section 3
sets out what temporal qualia are, and draws an analogy between the relationship
between temporal qualia and passage and the mind–body problem. Section 4 outlines
four alternative explanatory models for temporal qualia, arguing that passage-realist
models fail to offer any explanatory advantage with regard to our temporal qualia. In
Section 5, I argue that time perception illusions should not be read as supporting the
claim that temporal qualia are illusory, but rather motivate a ‘reductionist’ account
of temporal qualia according to which temporal qualia are in general reliable indica-
tors of change and motion in world. Section 6 sets out reductionism about temporal
qualia in further detail, defending it on naturalist grounds by demonstrating that it
is both continuous with and supported by empirical studies in time perception: first,
reductionism offers a pluralist account of temporal qualia as consisting of a cluster of
loosely related cognitive responses to physical change and motion, rather than offer-
ing a unified representation of passage, in-keeping with the pluralism of mechanisms
involved in time perception; second, reductionism is supported by the phenomena of

1See Paul (2010), Norton (2010), Prosser (2012, 2013, 2016), Hoerl (2014), Phillips (2014), and Baron
et al. (2015).

European Journal for Philosophy of Science (2020) 10: 88 Page 2 of 24



motion blindness, where subjects lack certain kinds of motion qualia. Section 7 is the
conclusion.

2 Temporal passage and temporal qualia: two independent
philosophical problems

2.1 Passage realism

Temporal experience is often offered as evidence in favour of the ‘A theory of time’,
and against the ‘B theory of time’. The A and B theories of time are standardly taken
to disagree over the ontological status of temporal passage. The A theory holds that
the following two facts hold independently of our existence and our temporal loca-
tion: (1) there is a privileged ‘present’ moment of time; (2) time passes. The B theory
rejects both (1) and (2), holding that any beliefs we have about the specialness of the
present, or of the objectivity of the flow of time, are to be explained as features of
our temporal perspective, rather than perspective-independent features of the world.2

Though (2) is often understood in terms of the movement of the present moment, the
concept of temporal passage is conceptually distinct from (1).3 ‘Temporal passage’
and ‘time flow’ are at base heuristic metaphors: we know what it is like to see a river
flow or an object pass us by, and the idea behind passage realism is that our tempo-
ral experience as a whole is like this in that time itself appears to pass or flow. Such
a metaphor is clearly problematic, since there appears nothing intrinsically special
about the flow of a river of the passing-by of an object that the perception of which
would constitute a perception or awareness of time as passing any more than any
other kind of motion or change. But such details about how to explicate the concept
of passage and its alleged phenomenological features can be put to one side since my
central aim is to get rid of the metaphor in the explanation of temporal qualia.

I will instead reserve the term ‘temporal passage’ in this paper for the idea
of something over-and-above the B-theoretic features of the world that has some
important connection to the kinds of processes and experiences we ordinarily term
‘temporal’. To unpack this a bit: the B theory holds the world to contain a num-
ber of temporal facts which are expressible in terms of relative spatial and temporal
locations, such as that there are temporally-extended objects that take on different
properties and positions at different times. Passage realism holds that beyond the B-
facts, time has some intrinsic dynamic quality that serves to distinguish it from space,
which is a feature of the world and not merely part of our conscious representation
of it. Since I am interested only in temporal passage, and not the idea of a privileged

2Though the B theory is antirealist about passage, it standardly assumes a preferred direction of time, as
implied by its usage of ‘earlier than’ as an ordering relation. I elsewhere (Farr 2012, 2018; Farr, The C
theory of time, unpublished) introduce and defend an alternative ‘C theory’ of time, according to which
time neither passes nor has a privileged direction. The C theory, I contend, treats temporal qualia in the
reductionist way I defend in this paper.
3We can imagine someone denying that time has a privileged present moment whilst still holding time to
pass in a sense in which space does not—for example, see Maudlin (2007, ch. 4).

European Journal for Philosophy of Science (2020) 10: 8 Page 3 of 24 8



present moment, I will use the terms ‘passage realism’ and ‘passage antirealism’ to
refer to the two sides of the debate rather than ‘A theory’ and ‘B theory’.4

2.2 Passage antirealism

Passage realism has been subject to a number of famous critiques: McTaggart (1908)
argues that the concept of temporal passage is incoherent; Broad (1938) and oth-
ers5 object that temporal passage requires the existence of multiple time dimensions;
Eddington (1928) argues that the concept of temporal passage plays no role in
physical theory; Putnam (1967) and Rietdijk (1966) hold that temporal passage is
incompatible with special relativity theory; and Gödel (1949) argues that temporal
passage is inconsistent with general relativity theory. A consequence of this lopsided
dialectic is that passage antirealism has had a relatively free ride, being explicated
primarily in terms of what it rejects. However, the passage antirealist nonetheless
requires a positive account of why time has the peculiar experiential features that it
does. A popular move is to regard passage as a kind of illusion associated with our
temporal experience that requires input from cognitive science — for instance (Paul
2010) argues that change and motion illusions provide an important insight into how
we could come to have an illusion of temporal passage.

2.3 Eliminating passage-talk

My contention, which I detail in Sections 5 and 6, is that insofar as empirical psy-
chology bears on the problem of temporal qualia, it serves to favour a reductionist
account of temporal qualia whereby they are understood as phenomenal features of
our range of abilities to detect real or illusory motion and change. I make the case
that the analysis of human motion and change perception provides no empirically-
motivated grounds for holding either that (a) our temporal qualia ontologically or
causally depend upon the passage of time, or (b) our temporal qualia form a unified
representation of a mind-independent phenomenon of temporal passage that accords
to the passage realist’s concept of passage. As such, there is no need to draw a con-
nection between the problems of temporal passage and temporal qualia, and thus
reductionism offers a more promising approach. Reductionism is an account of how
to understand what temporal qualia are, rather than an account of how to understand
temporal passage. Reductionism is most naturally understood as a passage antirealist
position, since it holds that there is no interesting link between our experience and
the concept of temporal passage, undermining the central claims of the passage real-
ist accounts I will consider. There is nonetheless logical space for someone to be a
reductionist about temporal qualia whilst holding that time passes for some indepen-
dent reason. This is a consequence of treating the problems of temporal qualia and
temporal passage as wholly independent of each other.

4Indeed, the passage realism and A/B theory debates themselves come apart in various ways. For instance,
Maudlin (2007) defends passage realism without the A theory, and Tallant (2010) defends a version of the
A theory without passage realism.
5This objection to temporal passage has been raised by Dunne (1939), Smart (1949) and Black (1959).

European Journal for Philosophy of Science (2020) 10: 88 Page 4 of 24



Siblings of such a reductionist position about temporal phenomenology have been
outlined6 and defended7 in the recent literature on the grounds that the claim that tem-
poral phenomenology is systematically illusory is conceptually problematic and/or
unintelligible. In particular Hoerl (2014) suggests that it is a mistake to hold that we
have a phenomenology of temporal passage at all. This is a claim about the phe-
nomenological character of temporal experience; indeed, Hoerl (p. 192) notes that
this is a further error theory to that of the illusionist: the illusionist’s belief that we
have non-veridical passage phenomenology is itself an illusion. While such a position
is welcome, I will not argue that we do not have passage phenomenology, nor that our
phenomenology in itself is what should motivate a passage-antirealist attitude over a
passage-realist one. On the contrary, I take it that we do have qualia that are worth
grouping and characterising as ‘temporal’, and these have a phenomenal character
that is commonly associated with the idea of time as passing. However insofar as we
do have temporal qualia, I argue that it is a mistake to regard such qualia as function-
ing as a representation of time as passing, since such a position is not forced through
philosophical argument, nor is such a claim useful in categorising the ways in which
we can successfully or unsuccessfully represent things like motion or change. Rather,
my central claim is that very tendency to relate the problems of temporal passage and
temporal qualia in the first place serves only to confuse two independent philosophi-
cal problems: nothing is gained in the explanation of temporal qualia by referring to
the concept of temporal passage.

3 What is the problem of temporal qualia?

A quale is a phenomenal, qualitative aspect of an experience, and qualia is the plural
form. The qualia of some experience are generally described as the ‘what-it’s-like’
properties of having that experience, such as what it is like to experience the spe-
cific shades of turquoise of the sea around the Great Barrier Reef. As such, qualia are
necessarily of a first-person nature; there are no qualia without experiencers. In the
temporal case, experiences of change and motion are widely appealed to as having
distinctively temporal qualia, with some holding these to be to some degree experi-
ences of the passage of time, such as Le Poidevin’s claim that we ‘see’ the passage
of time in ‘any motion or change at all.’ Visual perception of change and motion are
the most typically cited instances of the passage-like features of our experience, and
we’ll focus primarily on these.8

6Baron et al. (2015) term a related position ‘veridicalism’, which holds both that time does not pass, and
that we do not experience time as passing, hence temporal phenomenology is largely veridical and not
systematically illusory. Miller et al. (2018) detail a range of different veridicalist positions.
7Deng (2013) and Hoerl (2014) each express scepticism as to whether we have a phenomenology of
passage, and argue that the passage-antirealist (for Deng, the ‘B theorist’; for Hoerl, the ‘reductionist’
about temporal passage) possess sufficient resources to account for the apparently animated aspects of
change and motion perception without recourse to the passage realist’s ontology.
8The examples of change and motion we consider in this paper concern only visual perception. There are
various other sensory modalities with which we experience time, such as sound and touch, that we will
not consider. See Phillips (2014) for a recent survey piece that covers cross-modal temporal experience.

European Journal for Philosophy of Science (2020) 10: 8 Page 5 of 24 8



3.1 ‘Temporal qualia’ as an umbrella term

We can group change and motion qualia and other related kinds of qualia9—i.e. the
phenomenal character associated with veridical or illusory perception of change and
motion—under the general label ‘temporal qualia’. In this sense, ‘temporal qualia’
can be considered an umbrella term that refers to any qualia we typically associate
with the concept of time. I shall use the term in this neutral way, to refer to temporal
qualia as a whole and not to imply that there is some unique phenomenological prop-
erty shared by temporal qualia that other, non-temporal, types of qualia lack.10 The
following facts are uncontroversial: first, things change and move in the world; sec-
ond, we experience things as changing and moving; third, our experience of change
and motion has particular phenomenological features that we typically associate with
the concept of temporal passage; fourth, we can and do have change and motion
qualia that do not correspond to actual change or motion in the world, owing to
perceptual illusions.

To fix on the example of motion for a moment: there is something it is like to
see motion, and we standardly have motion qualia in response to seeing a moving
body, such as a bird flying past the window. Moreover, it is important that this set
of qualia is not simply a perception of motion, since perceptual illusions can trig-
ger non-veridical motion qualia in the absence of motion, and conversely cases of
motion blindness (which we consider in Section 6) show that one can have awareness
of motion without corresponding motion qualia.11 What is less clear and more con-
tentious is whether any part of our experience corresponds to temporal passage in an
analogous way.

3.2 Are temporal qualia representational?

Though the term ‘qualia’ is used to denote a variety of different concepts in the
philosophical literature on perception, I shall use it to refer to the phenomenal char-
acter of experience in general.12 The central debate regarding qualia is whether they
are representational in nature, with ‘qualia’ sometimes being used to denote only
non-representational features of experience. The distinctive ‘flow-like’ or ‘animated’

9It is often noted that there is something it is like to see one event succeed another, and to perceive different
lengths of duration, and as such succession and duration arguably involve relevant temporal qualia. I will
only refer to motion and change qualia for sake of brevity, but this is not to imply that these are the only
kinds of temporal qualia.
10See Prosser (2013 pp. 80–82) for a useful discussion of a related issue.
11Throughout this paper, I use ‘motion’ to refer to the relative motion of an object with respect to an
observer.
12Tye (2018) notes there are at least three popular alternative usages of the term: (2) in the context
of sense data theory, referring to the non-representational qualitative aspects of sense data; (3) as non-
representational features of experience in general (independent of the wider claims of sense data theory);
and (4) as intrinsic, ineffable aspects of experience.

European Journal for Philosophy of Science (2020) 10: 88 Page 6 of 24



features of temporal qualia are commonly implied in the philosophy of time litera-
ture to be representational in nature: passage realists standardly take their position to
be motivated by experience in that time appears to us as passing and we should take
physical time to possess such a property; and illusionists, though they are antirealist
about temporal passage, take our temporal qualia to constitute an illusion insofar as
they amount to an inaccurate representation of time as passing.

The reductionist account of temporal qualia I defend does not take temporal qualia
to be representational in this sense, and as such is in accord with the popular view of
qualia in general as non-representational. However, reductionism is very specific in
this regard. First, there is no ‘passage quale’—i.e. some qualia purely associated with
temporal passage that accompanies motion and change qualia. Second, to pick on a
specific type of temporal qualia, we should at best think motion qualia to function
as a generally reliable indicator of real motion, but not to indicate anything further,
such as there being an intrinsically flow-like quality of moving things. As a result,
temporal qualia do not in any sense form a representation of time as passing.

3.3 Temporal qualia and the explanatory gap

Just as the mind–body dualist takes physicalism to be unable to account for qualia
due to an explanatory gap between the mental and physical,13 the passage realist
can hold a passage-antirealist ontology (i.e. the B-facts) to be insufficient to account
for temporal qualia. Following Chalmers’ (1996) famous ‘zombie’ argument against
physicalism, the passage realist may take it to be possible for a world to share the
same B-facts as our world but lack the passage of time, and for inhabitants of such
a world to hence lack temporal qualia, such that their experience is somehow defi-
cient to ours in key respects in that things don’t appear to ‘flow’ in the same way.14

Maudlin (2007), for instance, implies that in a passageless world, people would not be
conscious — we come back to this issue in Section 4. Passage is often taken to be the
‘something extra’ required to bridge the gap and connect the manifest and scientific
images of time: Eddington (1928, p. 34; my emphases) notes that ‘[s]omething [i.e.
passage] must be added to the geometrical conceptions comprised in Minkowski’s
world before it becomes a complete picture of the world as we know it;’ and Davies
(1996, p. 275; my emphasis) stresses that the ‘sensation of a flowing time [. . . ] is an
aspect of time of great significance that we have so far overlooked in our description
of the physical universe’.

It is not necessary to hold that there is such an explanatory gap. To extend the
analogy between the philosophy of time and philosophy of mind, we can think of
the passage antirealist as akin to the physicalist: just as the physicalist takes qualia
to necessarily follow from the physical facts (e.g. pain qualia is just what it’s like
for something/anything to experience pain), the passage antirealist can take temporal

13Cf. Levine (1983).
14Though passage realism is in this sense analogous to kinds of dualism (such as Chalmers’ property
dualism), it doesn’t follow that the passage realist must reject physicalism. The passage realist could be a
physicalist but simply hold that B-facts are not sufficient to account for the properties of physical time.

European Journal for Philosophy of Science (2020) 10: 8 Page 7 of 24 8



qualia as a necessary consequence of beings like us interacting with a B-theoretic
ontology; temporal qualia don’t need any extra explanans.15

This problem is famously addressed by Williams (1951), who holds that it is a
mistake for passage realists to think that ‘they alone are “taking time seriously”’
(p. 458). As Williams notes, this falsely assumes that the passage antirealist does
not wish to account for the temporal idiosyncrasies of experience. On the contrary
the passage antirealist simply holds that the apparently dynamic aspects of temporal
experience that are generally termed as ‘passage’ or ‘flow’ are fully entailed by their
picture of time. This point is further emphasised by Prosser (2013), noting that since
‘both [passage realist and antirealist] theories, on their own terms, predict the same
experiences[, . . . ] experience does not favour one theory over the other’ (p. 71). As
such, we should not hold that ‘our experience of tense and temporal becoming [. . . ]
overwhelms any B-theoretic arguments against the reality of tense’ as Craig (2000, p.
165) claims, nor that ‘realism about tense is uniquely capable of making sense of the
phenomenology of temporal experience’ as Hare (2010, p. 762) suggests on behalf of
the passage realist. Sentiments such as these compromise the dialectic of the passage
debate by unfairly stacking the deck against the passage antirealist through implying
that they do not take their theory to entail nor take seriously temporal qualia.

It follows that the passage antirealist can simply deny the explanatory gap and
hold instead that temporal qualia are perfectly possible without temporal passage; the
antirealist is not seeking to deny that we have temporal qualia but rather offering a
theory of it that does not depend upon passage. What this brings to the fore is that
the dispute between passage realism and antirealism is not whether temporal qualia
are to be explained, but rather what is considered necessary in order for them to
be explained. The passage realist holds the passage of time to play crucial role in
explaining how it is that we have temporal qualia, and so by their lights the passage
antirealist lacks an explanation of how it is that we have temporal qualia. The passage
antirealist rejects this, holding instead that no explanation is needed for how we can
come to have temporal qualia in the absence of passage. It follows that the problem
of temporal passage is a priori in nature, and not, therefore, something to be settled
with reference to temporal qualia.

3.4 What is the explanatory problem of temporal qualia?

In treating the problem of temporal qualia independently of the problem of temporal
passage, I have two aims. Firstly, temporal qualia does not equate to an experience
of passage. In this context, Paul (2010) coins the phrase “experience as of” in order
to speak of our passage-like phenomenology without implying that it is veridical
(i.e. corresponds to real passage). However, my second aim is to go a step further
and avoid prejudging that our experience of time involves experience ‘as of’ passage

15Perry (2001) adopts this analogy in the case of ‘nowness’. Perry argues that Mellor’s (1998) argument for
the B theory amounts to a temporal version of Jackson’s (1986) ‘knowledge argument’, with A-theorists
holding that a property of ‘nowness’ is required to explain temporally-indexical beliefs.

European Journal for Philosophy of Science (2020) 10: 88 Page 8 of 24



at all.16 Rather, the very idea that temporal qualia in any coherent sense repre-
sent time as passing—whether veridically or erroneously—is a mistake that leads to
misrepresenting what it is about temporal qualia that stands in need of explanation.

Consider two alternative ways to pose the explanatory problem of temporal qualia:

Q1. Why does it appear to us as though time passes?
Q2. How do we account for the specific kinds of temporal qualia we have?

In the next two sections, I argue that Q1 poses a problem that does not stand in need of
explanation. In Section 4 I argue that the claim that passage is necessary for temporal
qualia plays no role in accounting for what is special about motion and change qualia.
In Section 5 I argue that passage antirealists, insofar as they do not share this claim,
are not required to address Q1—on their terms, the question is a non-issue. As such,
the claim that temporal qualia are illusory as regards temporal passage, and related
attempts to explain away passage as being a cognitive illusion, are fundamentally
misguided. Q2, on the contrary, represents a tractable and interesting issue that is
far more amenable to input from cognitive science. Sections 5 and 6 detail specific
ways in which cognitive science bears upon Q2, and crucially, how such empirical
investigation fits best with a reductionist account of temporal qualia.

4 How (not) to explain temporal qualia

In separating the concepts of temporal qualia and temporal passage, we can ask more
detailed questions about how they relate. First, is temporal passage necessary for tem-
poral qualia? And secondly, do temporal qualia represent temporal passage? These
two issues are independent but are often run together, and considering the different
combinations of yes/no answers to these questions gives us a range of positions as
laid out in Table 1. I’ll first summarise these positions before critiquing them.

Representational Realism. Temporal passage is necessary for temporal qualia.
Temporal qualia represent temporal passage.

Representational realism corresponds to the idea that we directly experience tempo-
ral passage. On this account, our temporal qualia track temporal passage insofar as
they are a veridical conscious representation of temporal passage and are caused by
temporal passage.

Inferential Realism. Temporal passage is necessary for temporal qualia. Temporal
qualia need not represent temporal passage.

Inferential realism relaxes the idea that we have direct experience of temporal pas-
sage, instead holding temporal passage to be a necessary precondition for temporal
qualia, and hence that we can legitimately infer that such a thing must exist in order
to account for our having temporal qualia.

16See Deng (2013) and Hoerl (2014) for criticisms of the claim that we have experiences ‘as of’ passage.

European Journal for Philosophy of Science (2020) 10: 8 Page 9 of 24 8



Table 1 The different strategies for explaining temporal qualia

TP=Temporal passage; TQ=temporal qualia; RR=representational realism; IR=inferential realism

Illusionism. Temporal passage is not necessary for temporal qualia. Temporal
qualia represent temporal passage.

Illusionism holds our experience of time to be fundamentally misleading in that
although time appears to us as passing, this is a cognitive illusion and fails to
correspond to a mind-independent feature of the world.

Reductionism. Temporal passage is not necessary for temporal qualia. Temporal
qualia do not represent temporal passage.

Finally, reductionism holds that temporal qualia neither depend upon nor represent
temporal passage: change and motion qualia (and any other kind of temporal qualia)
are simply indicators of things changing or moving over time. When I see a lorikeet
flying past my window, any flow-like qualities of my motion qualia are simply what
it is like to represent the lorikeet’s motion as it takes on a series of different positions
in my visual field relative to the background scenery over a short period of time.

4.1 Representational realism

Though I have argued in Section 3 that the problem of temporal passage is a priori
in nature and so is not to be settled by reference to temporal qualia, it is worth going
through independent shortcomings of passage-realist approaches to the problem of
temporal qualia. First, representational realism is the most extreme position of the
four approaches to temporal qualia in that temporal qualia function as the direct per-
ception of temporal passage. Though this view is reasonably intuitive, it is subject to
a basic epistemic problem that calls for a more sophisticated explanatory model of
temporal qualia. Eddington (1928, p. 91) notes that such a view ‘is tantamount to an
admission that consciousness, looking out through a private door, can learn by direct
insight an underlying character of the world which physical measurements do not
betray’. If temporal passage is something over and above the existence of changing
and moving things in the world, then the problem is how we could we gain epistemic
access to such a thing. Temporal passage is not something present in physics text-
books; we don’t need to know any special properties of the passage of time to account
for the behaviour of any known phenomena (except allegedly our first-person expe-
rience of time). As such, this requires some kind of special connection between our
brains and temporal passage that ‘goes around’ the physical sciences. There is good
reason to suppose then that if passage is to play a role in the explanation of temporal

European Journal for Philosophy of Science (2020) 10: 88 Page 10 of 24



qualia, it is not in the sense that our temporal qualia are offering a glimpse into an
underlying feature of the world.

4.2 Inferential realism

Inferential realism shares with representational realism the idea that temporal passage
plays a key role in explaining temporal qualia, but it relaxes the claim that we experi-
ence temporal passage—instead we can think of temporal passage as something that
is inferred by the realist from the general ‘feel’ of temporal qualia. Inferential realism
instead holds that the relationship between passage and temporal qualia is that the
former is necessary for the latter; without temporal passage, we wouldn’t have tem-
poral qualia. Recent advocates of such a position include Maudlin (2007) and Norton
(2010).17 Maudlin considers what we can call temporal zombie worlds18—worlds
physically identical to our own but stipulated to not contain temporal passage—and
argues that ‘unless one already has begged the central question’ against passage real-
ism, it follows that ‘the state of this [zombie] world is so unlike the physical state
of anything in our universe that to suppose that there are mental states at all is com-
pletely unfounded’ (Maudlin 2007, p. 124). In a similar vein, Norton argues that
temporal passage is required to explain why our psychological timeline matches the
temporal order of events in the world, holding that ‘if passage is an illusion, there
must be some mechanism that blocks us perceiving the future’ (Norton 2010, p. 30),
implying like Maudlin that without passage we would not have the kind of temporal
experience that we do.

Though inferential realism avoids the epistemic problem faced by representational
realism, it faces a more basic problem regarding the relationship between temporal
passage and temporal qualia: there is no sense in which inferential realism can explain
why the paradigm instances of temporal qualia—motion and change qualia—are spe-
cial vis-à-vis passage. Take Maudlin’s suggestion that inhabitants of a passageless
temporal zombie world would not have mental states: if temporal qualia and tempo-
ral passage are related in this way, then any conceivable mental state would stand in
the same dependence relation to temporal passage regardless of whether it concerns
experience of time, or thoughts about the size of elephants’ ears, or whatever. This
account fails because it is too general: there is no unique link between temporal pas-
sage and the characteristically temporal kinds of qualia, such as motion and change
qualia, meaning that such a dependence relation between temporal qualia and tem-
poral passage provides no explanation of what makes temporal qualia special for the

17It should be noted that both Maudlin and Norton make claims that sound as though temporal passage is
in some sense experienced, more in line with representational realism. However, both put forward models
in which the key relation between temporal qualia and temporal passage is that the former counterfactually
depend upon the latter, in line with inferential realism.
18Maudlin’s points are made specifically against Price’s (1996) version of Williams’ (1951) thought exper-
iment, involving a world physically identical to our own but stipulated to not contain temporal passage.
Price argues that there is no reason to suppose beings in such a world would experience time differently
from ourselves, since on any fair mapping of physical states from the passage world to the no-passage
world, the brain states of individuals would be mapped from the former to the latter.

European Journal for Philosophy of Science (2020) 10: 8 Page 11 of 24 8



passage realist. Prosser (2013, p. 82) picks on this generality of explanation in pas-
sage realist accounts of temporal qualia, noting that even if such accounts were true,
temporal qualia would fail to constitute a ‘unique, perception-constituting relation
to the passage of time’.19 But this point goes deeper: even if the realist is happy to
weaken the perceptual claim and accept that temporal qualia function as something
less than a perception or representation of passage, as inferential realist does, the key
explanatory problem remains: there is no account at all of why motion and change
qualia in particular should be analogous in any sense to the passage of time, since
other mental states equally dependent on temporal passage clearly are not. As such,
inferential realism does not explain temporal qualia.

5 Abusing your illusion

Putting passage realist models to one side, it is common to portray passage-antirealist
positions (i.e. B-theories) as holding some kind of illusionism about temporal qualia.
For instance, from the passage-antirealism camp: Smart (1980, p. 3) holds that ‘the
alleged passage of time [. . . ] is an illusion’; and Prosser (2012, p. 92) holds that
‘the B-theory cannot be regarded as fully satisfactory until an adequate account has
been given of the illusion of passage’. Moreover, passage realists typically cite the
perceived flaws of illusionism as supporting their position: Davies (1996, p. 275) is
‘repelled by the claim that [passage] is only an illusion or misperception’; Maudlin
(2007, p. 135) holds that ‘all the philosophizing in the world will not convince us that
these facts [that time appears to pass] are mere illusions’; and Norton (2010, p. 23)
remarks that ‘[e]xplaining passage away as an illusion is an instance of a desperate
stratagem that has been used to ill effect elsewhere when we become too eager to
explain away an awkward fact’.

I share the latter sentiments that it is undesirable to hold temporal qualia to be sys-
tematically illusory, but think that rather than supporting passage realism, it supports
a best-of-both-worlds option, which is to reject the idea that temporal qualia repre-
sent passage in the first place. The study of time perception better supports the claim
that temporal qualia are in general veridical, with time perception illusions highlight-
ing specific exceptional circumstances in which temporal qualia erroneously indicate
change and motion in unchanging and motionless objects.

5.1 When temporal qualia are illusory

There is a range of well-studied time perception illusions that are instructive with
respect to temporal qualia since they constitute cases where temporal qualia demon-
strably fail to function as accurate representations of the world. These are illusions
that involve subjects experiencing change and motion qualia in the absence of
changing or moving stimuli. These include (but are not restricted to):

19Prosser specifically talks of temporal phenomenology rather than qualia, but for our purposes this
difference in terminology makes no odds.

European Journal for Philosophy of Science (2020) 10: 88 Page 12 of 24



Phi Phenomenon. A series of still images of differently positioned dots presented
to an observer in rapid succession give rise to the illusory perception of a single
enduring object in continuous motion between the dot locations (cf. Wertheimer
1912; for a demonstration, see Bach 2014a).

Motion Aftereffect. A subject’s visual system adapts to a moving image, such that
after the stimulus is removed, the subject appears to perceive the inverse motion
(cf. Mather et al. 1998; for a demonstration, see Bach 2014b).

Peripheral Drift. A still image appears to contain motion as the eye scans around
the image (cf. Fraser and Wilcox 1979. A particularly vivid example of this is
Kitaoka’s rotating snakes illusion [Fig. 1]).

Each of these three kinds of motion illusion demonstrates a different way in which
temporal qualia can be illusory. The two that are of most interest are the motion
aftereffect and peripheral drift illusions. In the case of motion aftereffect illusions,
temporal qualia are illusory insofar as they continue after a motion-involving stimu-
lus is removed. A paradigm example is the ‘waterfall illusion’, where after staring at
a waterfall for some time and then shifting focus to the adjacent rock face, the rock
face appears to be moving upwards, in the opposite direction to the water. Motion
aftereffect illusions are the product of our visual system adapting to a continuous
motion by counteracting to the motion, with the result of reducing the intensity of the
perceived motion and the corresponding sense of disorientation. A consequence of
this is that once the stimulus is removed, the neural adaptation creates the illusion of
motion in the opposite direction to that of the original stimulus. Thus, one has motion
qualia that are an effect of real motion, but continue in the absence of that motion, and
also give the appearance of motion in the opposite direction. The resulting motion
qualia are not veridical, although they are a consequence of past motion. Peripheral

Fig. 1 The Rotating Snakes illusion (Kitaoka 2016)

European Journal for Philosophy of Science (2020) 10: 8 Page 13 of 24 8



drift illusions are of greater interest in this regard insofar as the motion qualia are
not a consequence of actual motion in the object being perceived. As the name sug-
gests, a peripheral drift illusion involves the illusion of motion in the periphery. Such
illusions incorporate repeated patterns of asymmetric luminance that in peripheral
vision appear as motion in the dark-to-light direction, as vividly depicted in Fig. 1.20

The motion qualia are generated without the presence of a moving stimulus, unlike
motion aftereffect illusions.21

The phi phenomenon represents a different kind of illusion with respect to tempo-
ral qualia. In the paradigm case of a pair of flashing dots sequentially appearing at
opposite ends of a screen, the observer typically projects a single dot moving at high
speed from side to side.22 Such a case is interesting with regard to temporal qualia
insofar as it provides an example in which the perceived motion of the dot is illu-
sory. Moreover, this case has been taken as an instance of human subjects using an
‘endurantist’ representation of the dots as a single, enduring dot (for instance, both
Paul 2010 and Prosser 2013 argue along these lines. I consider Paul’s treatment of
this later in this section).

Time perception illusions demonstrate that temporal qualia can be produced in the
absence of actual physical change or motion in the relevant object being observed,
and hence are illusory in this respect. A consequence of this is that there is a key
sense in which temporal qualia are, in general, veridical: our temporal qualia, except
under specific well-studied and well-understood conditions, reliably indicate and are
triggered by change and/or motion of the perceived objects. Time perception illusions
represent anomalous cases, and the study of the psychophysical and physiological
details of these aids the understanding of how the brain produces the appearance of
motion and change, and under precisely what conditions these fail to be veridical.

5.2 Why illusions don’t imply illusionism

The veridical nature of temporal qualia in ordinary conditions stands in direct contrast
to the central claim of illusionism, which is that temporal qualia are systemati-
cally illusory insofar as they represent something—temporal passage—that does not
exist. Paul (2010) makes the case that time perception illusions, particularly the phi
phenomenon, are illustrative in understanding illusionism. In the case of the phi
phenomenon—let’s again use the case of the flashing dots—, the brain fills in the
space between the two dot locations so it appears as though a single dot is traveling
at high speed between the two locations. Paul suggests by analogy:

20See Fraser and Wilcox (1979) for the original presentation of the peripheral drift illusion and Faubert and
Herbert (1999) for analysis. Backus and Oruç (2005) additionally offer an analysis of Kitaoka’s rotating
snakes illusion.
21Backus and Oruç (2005) argue that this type of illusion is due not to the shift of one’s visual focus around
the image, but rather ‘fast and slow changes over time in the neuronal representation of contrast [. . . ] or
luminance’ (p. 1055).
22In the case of the ‘color-phi’ illusion, the dots are of different colours, and so the illusory moving dot
gradually changes colour.

European Journal for Philosophy of Science (2020) 10: 88 Page 14 of 24



[W]hen we have an experience as of passage, we can interpret this as an experi-
ence that is the result of the brain producing a neural state that represents inputs
from earlier and later temporal stages and simply ‘fills in’ the representation
of motion or of changes. Thus, according to the [illusionist],23 there is no real
flow or animation in changes that occur across time. Rather, a stage of one’s
brain creates the illusion of such flow, as the causal effect of prior stages on
(this stage of) one’s brain. (Paul 2010, p. 352; my emphasis)

This gives a specific picture of how an illusionist explanation of temporal qualia
might work. The idea is that by drawing on the sense in which we can have motion
qualia in the absence of corresponding motion in the relevant physical object, the
passage antirealist can give a general heuristic for how in principle one can have
temporal qualia in a world without passage. I’ve argued that this is not a task which
the passage antirealist need take up. Instead, the reductionist about temporal qualia
rejects the idea that we have ‘experiences as of passage’ insofar as (a) there is no sin-
gle ‘passage quale’—rather the ‘flow’ or ‘animation’ are features of temporal qualia
in general (such as motion qualia)—, and (b) temporal qualia in general don’t repre-
sent time as passing in the way in which the concept of temporal passage is ordinarily
understood (as something over and above the B-facts). In light of this, the reduc-
tionist denies that there is an illusion to explain here: if the flow and animation are
simply what it is like to perceive real or imaginary motion and/or change, then it is
not illusory, since it in general reliably tracks real change and motion.

There are strong independent reasons for taking such an error theory to be in vain.
Although there is certainly a general analogy between, on the one hand, our ability to
project motion qualia in the absence of a moving stimulus, and on the other hand, the
illusionist’s claim that we project temporal passage onto reality as a whole despite
there being no such thing, there is a major problem with such an approach: there
are key senses in which the term ‘illusion’ is explanatorily useful in the first case
that fail to carry over to the second and ultimately promote unnecessary confusion
about the nature of our temporal experience. Take the rotating snakes illusion (Fig.
1): the illusion consists in the appearance of motion as a result of looking at a still
image. Such illusions involve a perceptual stimulus giving rise to misleading qualia.
A hallmark of such illusions is that there are independent ways of verifying that the
stimulus lacks such a quality—in this case, we can independently verify in a number
of ways that Fig. 1 is a still image, and so confirm that our motion qualia are mislead-
ing us.24 Indeed a key feature of perceptual illusions is that they are localised in that
they generally do not apply wholesale across all of our sensory modalities, allowing
us to establish that they are indeed illusions. However, the illusionist’s account of the

23Paul uses the term ‘reductionist’, so it is necessary to distinguish the position to which she refers from
the position I call reductionism. Paul is referring to the reductionist about temporal passage, such as the B
theorist, who takes our experience of time to not depend upon the reality of temporal passage. This picks
out passage antirealism in general. She also takes ‘reductionism’ to be committed to the idea that passage
is an illusion. I use ‘reductionism’ as shorthand for ‘reductionism about temporal qualia’, which holds that
temporal qualia reduces to motion qualia, change qualia, and the like.
24I use the rotating snakes illusion here as my example, but the same reasoning applies also to Paul’s
example of the phi phenomenon.

European Journal for Philosophy of Science (2020) 10: 8 Page 15 of 24 8



illusion of temporal passage is of a different kind.25 In the case of illusionism, tem-
poral qualia are both permanently and systematically illusory insofar as: (1) every
temporal quale erroneously represents something—temporal passage—that does not
correspond to anything in reality; (2) the illusion of passage is consistent across all
of our sensory modalities.

With regard to (1), the illusionist is committed to the unwelcome consequence
that ordinary experiences of motion and illusory motion qualia are equally illusory
with respect to passage, and as such, there is a major disanalogy between standard
cognitive illusions and the alleged illusion of passage: according to the illusionist, we
are under the illusion of passage both in the case that we observe real motion, such
as seeing a bird fly by, and in the case that we observe illusory motion, such as with
the rotating snakes illusion.26

With regard to (2), the illusionist’s alleged illusion of passage would presumably
also have to be cross-modal in nature, affecting all of our sensory mechanisms, so
that time would not only visibly appears to pass, but also sound and feel as though it
were passing. There is no doubt that the rotating snakes illusion would be all the more
powerful and interesting were it to also produce the illusion of auditory and tactile
motion together with visual motion, but there is no such all-encompassing motion
illusion to be found in the literature.

Whereas the concept of an illusion is useful and informative in the case of whether
motion qualia tracks actual motion, it is by contrast unhelpful to use the same con-
cept with respect to whether all types of temporal qualia track temporal passage. In
the former case, we know how to measure whether something has moved in a way
that corresponds to one’s motion qualia (in part due to the fact that such illusions are
typically restricted to one of the sensory modalities), but in the latter case, it is not
clear what could possibly count as a measurement of whether or not time is pass-
ing.27 All in all, the alleged analogy between the illusionist account of passage and
cases of change and motion illusions breaks down upon analysis. The usefulness and
empirical meaning of the term ‘illusion’ in cases of motion and change illusions does
not carry over to the case of temporal passage; nothing, it seems, is gained philo-
sophically by taking an illusionist account of temporal qualia. As such, illusionism’s
key thesis fails to offer any explanatory advantage regarding temporal qualia over
reductionism.

On the contrary, it is preferable to consider illusions like the rotating snakes (Fig.
1) in reductionist terms. When considering the illusory motion qualia, the reduc-
tionist seeks no further explanation as to why in addition to the motion qualia we

25As Norton (2010, p. 23)notes: ‘[w]e know what illusions are like and how to detect them. Passage
exhibits no sign of being an illusion’.
26Alternatively, Deng (2013) suggests that the analogy drawn by Paul is itself ambiguous: either the illu-
sion of motion in the phi phenomenon and the illusionist’s alleged illusion of passage are distinct illusions;
or they are different aspects of the same illusion. If the former, Deng suggests that ‘it is hard to see what
the second illusion [the illusion of passage] could be’ (p. 377). If the latter, it is unclear what is to be
gained by the analogy.
27Indeed, on standard passage-realist accounts, the passage of time is continuous and ubiquitous—it is not
something that stops and starts or varies from place to place.

European Journal for Philosophy of Science (2020) 10: 88 Page 16 of 24



appear also to experience animation or flow in the image. To think there is some-
thing further that stands in need of explanation is, according to reductionism, to make
a category mistake—the appearance of animation or flow in the image is just what
it is like to represent motion. In holding the ‘dynamic’ and ‘flow-like’ qualities of
temporal experience to be features of what it is like to represent motion or change,
the reductionist gives up the idea that something further than motion—i.e. temporal
passage—is represented by temporal qualia.

6 An appetite for reduction

To recapitulate, reductionism about temporal qualia holds that:

(1) our temporal qualia amount to no more than the sum of change and motion
qualia and related kinds of qualia;

(2) each of these are simply what it is like to perceive the relevant physical
phenomenon (motion, change, etc.);

(3) there is no extra ‘passage quale’ that accompanies or unifies such qualia; and
(4) such qualia do not amount to a collective representation of temporal passage as

something over and above a passage-antirealist (B-theoretic) ontology.

This section outlines in more detail the reductionist account of temporal qualia
and shows how it is supported by and continuous with various empirical work in the
study of time perception.

6.1 Understanding reductionism

The distinction between reductionism and illusionism is analogous to that between
moral naturalism and moral error theory. Moral error theory shares with moral real-
ism the idea that moral statements are truth-apt and that they refer to a realm of
non-reductive moral facts, but holds that there are no such facts and so moral state-
ments are systematically false. Moral naturalism holds that moral statements refer to
contingent worldly matters of fact, and in this way avoids both the epistemic prob-
lems of moral realism and error theory’s undesirable consequence that all of our
moral talk is outright false. Analogously, I’ve argued that the central problem with
illusionism is precisely that it shares with passage realism the claim that our temporal
qualia represent temporal passage, which is something over and above motion and
change facts, and since illusionism is a passage-antirealist position, it consequently
holds that our temporal qualia are systematically in error. I’ve argued that this error-
theoretic claim of illusionism plays no important explanatory role regarding temporal
qualia, and the passage antirealist is better off giving up the claim that temporal qualia
represent temporal passage. Just as moral naturalism allows for empirical import
into ethical questions, reductionism about temporal qualia shifts the focus of enquiry
about temporal qualia onto empirical issues concerning time perception.

European Journal for Philosophy of Science (2020) 10: 8 Page 17 of 24 8



6.2 Pluralism about temporal qualia

Reductionism gives a pluralist account of temporal qualia in that it takes temporal
qualia to consist of a number of different kinds of qualia that are not necessar-
ily unified by some particular phenomenological property. This pluralist account of
temporal qualia makes sense of how we represent change and motion and under
what circumstances our motion and change qualia are misleading. Indeed, the kinds
of experience that we take to be temporal are in general quite varied and distinct,
whether it be seeing the change of a flickering picture, the motion of a bird, sens-
ing that a situation has endured for too long, or having the more abstract feeling of
disorientation at time having elapsed after waking from an unexpected nap. This plu-
ralism of temporal qualia is demonstrated even within our main case study of motion
perception, which is standardly categorised into first and second orders. First order
motion perception involves basic motion sensors that are sensitive to spatiotemporal
variations in luminance and colour. Second order motion perception involves more
complex qualities such as texture and contrast. The first and second orders differ in
a number of ways. For instance, in the case of motion aftereffect, first-order motion
detectors are more sensitive to the adaptation to the stimulus, since their afteref-
fects last for twice the duration as those of second-order detectors (Mather 1991, p.
164),28 and also second order but not first order motion detection tails off markedly
in peripheral vision (Pantle 1992).29

Though it is an open question how exactly first and second order motion peception
relate, a wide range of studies on cognitive impairments in patients indicate that first
and second order motion detection owe to different neural pathways and mechanisms
(cf. Vaina and Cowey 1996; Nishida et al. 1997; Greenlee and Smith 1997; Vaina
et al. 1998). For instance, Vaina and Soloviev (2004, p. 197) suggest that ‘first-order
motion is carried out by mechanisms along the dorsal pathway in the occipital lobe,
while the second-order motion by mechanisms mostly along the ventral pathway’.
Such studies support a pluralistic understanding of motion perception, suggesting
that motion qualia owe to a range of distinct neural processes in response to a range
of different kinds of stimuli. This supports the wider idea that temporal qualia are
associated in a number of different ways with a range of distinct kinds of perception.
This pluralist view of temporal qualia does not cohere to the passage realist view
that temporal qualia are a response to a single phenomenon (passage), nor to the
shared view of passage realists and illusionists that temporal qualia are a unified
representation of a single phenomenon (passage).

6.3 Motion blindness and temporal qualia

The study of motion blindness, or ‘akinetopsia’, is of particular relevance to the
understanding of temporal qualia. In such cases, patients have been noted to have

28See also (Ledgeway and Smith 1994) for an examination of the asymmetric durations of the motion
aftereffect in the cases of first and second order motion.
29For a recent survey of first and second order motion detection, see Nishida (2011).

European Journal for Philosophy of Science (2020) 10: 88 Page 18 of 24



‘perceptual experience of a moving target as if the visual stimulus remained station-
ary but appeared at different successive positions’ (Zihl et al. 1983, p. 314),30 and so
in effect have awareness of change in position without accompanying motion qualia.
Most notably, with respect to explaining the flow-like quality of temporal qualia,
Zihl et al. (1983, p. 315) describe an affected patient’s ability to pour coffee as com-
promised ‘because the fluid appeared to be frozen, like a glacier’. Zihl et al’s study
concerns a patient, LM, with acute akinetopsia, due to bilaterally symmetric damage
to the lateral temporo-occipital cortex, such that LM complained of ‘a loss of move-
ment vision in all three dimensions’ (p. 315), restricting her ability to judge the speed
of approaching trains, pour drinks without overfilling, and cross roads; for instance
LM reported that ‘people [are] suddenly here or there but I have not seen them mov-
ing’. Studies on LM revealed that her perception of motion in depth was ‘completely
abolished’ (p. 334), with some preservation of motion perception in targets moving
along the horizontal and vertical axes of LM’s inner visual field, though with no such
motion perception in the periphery. The motion blindness was restricted to visual
motion, with LM responding normally to both tactile and acoustic motion.

Zihl et al. (1983) furthermore studied LM’s motion perception with respect to two
of the motion illusions described in Section 5, first the phi phenomenon, and sec-
ond motion aftereffect. LM lacked the ability to perceive phi-phenomenon: when
presented with several variations of the successive presentation of two differently-
positioned dots, ‘[u]nder no combination of conditions did the patient report apparent
movement. She always reported two independent light spots,’ in contrast to the con-
trol subject. Similarly, LM had significantly limited susceptibility to the motion
aftereffect, in comparison to a control subject. In the case of a left-to-right-moving
stimulus:

The patient reported some kind of a motion aftereffects in only 3 of the 10 trials.
Its duration, however, was rather short (1.2, 1.4 and 2.1 s) when compared with
the normal subject tested under the same conditions (mean duration 6.7 s; 5
inspection periods). The patient described the motion after effect as an ’unrest’
of the pattern, but never as movement. (p. 330)

These and other studies (cf. Zeki 1991) on patients with varying degrees of akine-
topsia fit with the reductionist view of temporal qualia in a key way: the partial loss
of the ability to detect motion is accompanied by a loss of temporal qualia. Indeed,
the literal flow of a fluid is specifically reported to be viewed as ‘frozen [. . . ] like a
glacier’ in the case of LM. It is hard to think of a more exact analogy with the static
vs dynamic pictures standardly put forward within the debate between passage-realist
and passage-antirealist theories of time (i.e. the central disagreement between A- and
B-theorists). In this sense, we can see that the akinetopsic lacks certain temporal
qualia, and accordingly there is a reduced flow-like aspect of experience. The reduc-
tionist explanation here could not be simpler—the covariance of the flow-like quality
of experience with the ability to represent motion is explained in terms of the former
being a feature of the latter; for the reductionist the apparently animated quality of

30Zihl et al. (1983) are here referring to a patient studied by Pötzl and Redlich (1911).

European Journal for Philosophy of Science (2020) 10: 8 Page 19 of 24 8



perceiving real or imaginary motion is nothing further than having motion qualia; it
is simply what it is like to perceive motion. The fact that the akinetopsic has restricted
temporal qualia compared to the control subject both in cases of real and illusory
motion is explained, according to reductionism, by the fact that the akinetopsic has a
restricted ability to represent motion.31

For the passage realist and the illusionist there is extra conceptual apparatus with
which to understand the case of akinetopsia, since these positions allow us to distin-
guish between motion qualia — what it is like for something to appear in motion —
and passage qualia — what it is like for time to appear to pass. There are two broad
options: either (1) the loss of motion qualia does not affect the akinetopsic’s passage
qualia; or (2) the akinetopsic has diminished passage qualia. Let’s go through each
of these options in turn. In case of (1), it is unappealing to hold that the akinetop-
sic’s passage qualia is unaffected, since the missing qualia — the flow-like quality of
motion — seems to be a prime candidate for what constitutes the feeling of tempo-
ral passage on these accounts.32 As such, the second option would appear to be the
preferred one, that motion blindness involves a loss of passage qualia.

In the case of (2), we require some account of why it is that motion qualia and pas-
sage qualia covary in this way. It may very well be possible to extend one’s account of
realism or illusionism to accommodate this covariance of motion and passage qualia
in a coherent and elegant way. However, such a move would be motivated by one’s
background commitment to realism or illusionism rather than being motivated by the
phenomena. Unless there are good independent empirical grounds for thinking that
passage qualia could come apart from the set of things like motion qualia, change
qualia, etc., then there is no motivation to adopt such positions in order to account
for phenomena like motion blindness. One such possibility would be if there were a
phenomenon whereby a subject could be stimulated to experience qualia consistent
with the flow-like qualities of temporal qualia, but without accompanying motion or
change qualia. The problems here are, first, it is hard to know how such a thing could
possibly be established, and second, if such a thing were established, it would fail to
explain why perceptions of change and motion appear to be distinctively temporal, as
opposed to other kinds of qualia, after all.

The reductionist needs no such gymnastics. My suggestion is that the flow-like
aspect of motion qualia—that which is extremely vivid in Fig. 1—is both (a) a prime

31An interesting related case to that of akinetopsia is that of so-called ‘miracle cure’ patients, such as
the case of SB (Gregory and Wallace 1963), who regained sight having been effectively blind since early
childhood. SB subsequently had great difficulty tracking an individual object through movement, or whilst
seeing it from different angles, resulting in a restricted ability to perceive an individual object as in motion.
See Kelly (2005) for a discussion of this in relation to akinetopsia.
32One might suppose that there is still useful logical space here for distinguishing motion qualia from
the appearance of passage for the following reason: in order for a fluid to appear frozen, is has to do
so as time passes. I don’t agree. First, such cases of motion blindness are usually understood in terms
of time appearing to be like a series of still snapshots; while none of these visibly endure, they can be
assigned an apparent duration with reference to the patient’s other sensory modalities, since things like
auditory time perception are unaffected in cases of visual motion blindness. Second, B theorists of time
have provided plentiful resources for talking about things like temporal extension and duration, such as
the idea of something being frozen for some period of time, without making reference to the idea of time
as passing.

European Journal for Philosophy of Science (2020) 10: 88 Page 20 of 24



example of the qualities of temporal qualia that are standardly taken to relate to the
concept of temporal passage, and (b) just what it is like to ordinarily perceive real
or illusory motion. In LM’s case, the inhibited motion perception leads to a loss of
motion qualia in cases of observing moving bodies and in being presented with visual
motion illusions. If we are to look to empirical work in order to analyse and under-
stand temporal qualia, the study of akinetopsia seems to be of special relevance, and
such studies neatly fit a reductionist account of temporal qualia, and alone provide
no additional need to make reference to the concept of temporal passage.

7 Summing up

Our conclusions are twofold. First, there are two importantly distinct explanatory
programs concerning temporal qualia—(a) how temporal qualia relate to the con-
cept of temporal passage, and (b) how a different kinds of temporal qualia are to be
explained in terms of perception and cognition—, of which I’ve argued only the latter
need be addressed. Second, I’ve argued for a reductionist account of temporal qualia
over the alternative approaches (representational realism; inferential realism; and
illusionism). Reductionism, unlike the alternative three approaches, considers tempo-
ral qualia entirely independently of the concept of temporal passage. This is welcome
for a number of key reasons: (i) no explanatory advantage is gained with respect to
temporal qualia by referring to temporal passage; (ii) the question of whether tem-
poral qualia are illusory with respect to passage is entirely independent of whether
temporal qualia are illusory with respect to change, motion and other temporal fea-
tures of the world, and running the two together creates grounds for confusion; (iii)
the reductionist account of temporal qualia is continuous with and well supported by
empirical studies in time perception.

These conclusions address several core issues in the philosophy of time. Our
experience of time is widely taken to be central to the debate between A and B the-
orists insofar as it’s taken weigh in on whether one should be realist about temporal
passage. However, on the contrary we’ve seen that the relevant phenomenological
aspects of our temporal experience—temporal qualia—cannot settle the passage real-
ism debate. This is because the realism debate ultimately hangs on the background
issue of whether temporal passage is necessary for temporal qualia, and this amounts
to a normative debate over how temporal qualia ought to be explained. Furthermore,
it is commonly argued that the explanatory task for the passage antirealist (or B-
theorist) is to account our dynamic experience of time in a static universe. However,
to understand the passage antirealist’s task in this way is to give too much value to
the terms of the passage debate, and to run together the problems of temporal passage
and temporal qualia. We’ve seen that insofar as empirical work in the psychology of
time can illuminate the issue of temporal qualia, it does so in terms of how the var-
ied types of temporal qualia that we ordinarily have are grounded in our cognition of
processes in the world. Questions of this type are not only amenable to empirically-
informed philosophy, but a considerable amount of relevant empirical work has been
carried out and it is known in great detail how different kinds of temporal qualia are
projected onto our experience by parts of our brain in response to certain triggers,

European Journal for Philosophy of Science (2020) 10: 8 Page 21 of 24 8



and what functions these have and why we might have developed them. Reflection on
such studies, I’ve argued, supports a reductionist account of temporal qualia, suggest-
ing that our temporal experience consists of a range of different kinds of perception
that in ordinary conditions reliably indicate various kinds of physical processes in the
world, rather than collectively tracking or representing an independent phenomenon
of temporal passage.

Acknowledgments This paper dates back to an abandoned chapter of my PhD thesis, and has evolved
through discussions with colleagues at the universities of Sydney, Queensland and Cambridge. I’m espe-
cially thankful to Alex Holcombe, Patrick Goodbourn, Natalja Deng, Pete Evans, Milena Ivanova, Adrian
Bardon, Antony Eagle and two anonymous referees for helpful comments, and to audiences in Queensland,
Munich, Cambridge, Bristol and the 4th Annual IAPT Conference in Gargnano for all kinds of unexpected
reactions.

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 Interna-
tional License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution,
and reproduction in any medium, provided you give appropriate credit to the original author(s) and the
source, provide a link to the Creative Commons license, and indicate if changes were made.

References

Bach, M. (2014a). Colour phi phenomenon. http://www.michaelbach.de/ot/col-colorphi/.
Bach, M. (2014b). http://www.michaelbach.de/ot/mot-adapt/index.html.
Backus, B.T., & Oruç, I. (2005). Illusory motion from change over time in the response to contrast and

luminance. Journal of vision, 5(11), 10–10.
Baron, S., Cusbert, J., Farr, M., Kon, M., Miller, K. (2015). Temporal experience, temporal passage and

the cognitive sciences. Philosophy Compass, 10(8), 560–571.
Black, M. (1959). The “direction” of time. Analysis, 19(3), 54–63.
Broad, C.D. (1938). Examination of McTaggart’s philosophy Vol. II. Cambridge: Cambridge University

Press.
Chalmers, D.J. (1996). The conscious mind: in search of a fundamental theory. Oxford: Oxford University

Press.
Craig, W. (2000). The tensed theory of time: a critical examination. Dordrecht: Kluwer.
Davies, P. (1996). About time: Einstein’s unfinished revolution. Simon and Schuster.
Deng, N. (2013). On explaining why time seems to pass. The Southern Journal of Philosophy, 51(3),

367–382.
Dunne, J. (1939). An experiment with time, 5th edn. London: Faber and Faber Limited.
Eddington, A.S. (1928). The nature of the physical world. Cambridge: Cambridge University Press.
Farr, M. (2012). Towards a C theory of time: an appraisal of the physics and metaphysics of time direction.

Ph.D. thesis. Bristol: University of Bristol.
Farr, M. (2018). Causation and time reversal. The British Journal for the Philosophy of Science.
Faubert, J., & Herbert, A.M. (1999). The peripheral drift illusion: a motion illusion in the visual periphery.

Perception, 28(5), 617–621.
Fraser, A., & Wilcox, K.J. (1979). Perception of illusory movement. Nature, 281, 565–566.
Gödel, K. (1949). A remark about the relationship between relativity theory and idealistic philoso-

phy. In Schilpp, P.A. (Ed.) Albert Einstein: philosopher-scientist, volume 7 of the library of living
philosophers (pp. 557–562). Evanston: The Library of Living Philosophers, Inc.

Greenlee, M.W., & Smith, A.T. (1997). Detection and discrimination of first-and second-order motion in
patients with unilateral brain damage. Journal of Neuroscience, 17(2), 804–818.

Gregory, R., & Wallace, J. (1963). Recovery from early blindness. Experimental Psychology Society
Monograph, 2, 65–129.

Hare, C. (2010). Realism about tense and perspective. Philosophy Compass, 5(9), 760–769.

European Journal for Philosophy of Science (2020) 10: 88 Page 22 of 24

http://creativecommons.org/licenses/by/4.0/
http://www.michaelbach.de/ot/col-colorphi/
http://www.michaelbach.de/ot/mot-adapt/index.html


Hoerl, C. (2014). Do we (seem to) perceive passage? Philosophical Explorations, 17(2), 188–202.
Jackson, F. (1986). What mary didn’t know. The Journal of Philosophy, 83(5), 291–295.
Kelly, S.D. (2005). The puzzle of temporal experience. In Brook, & Akins (Eds.) Cognition and the brain:

the philosophy and neuroscience movement. Cambridge: Cambridge University Press.
Kitaoka, A. (2016). http://www.ritsumei.ac.jp/akitaoka/index-e.html.
Le Poidevin, R. (2007). The images of time: an essay on temporal representation, Oxford University Press,

Oxford.
Ledgeway, T., & Smith, A.T. (1994). The duration of the motion aftereffect following adaptation to first-

order and second-order motion. Perception, 23(10), 1211–1219. PMID: 7899037.
Levine, J. (1983). Materialism and qualia: the explanatory gap. Pacific Philosophical Quarterly, 64(4),

354–361.
Mather, G. (1991). First-order and second-order visual processes in the perception of motion and tilt.

Vision Research, 31(1), 161–167.
Mather, G., Verstraten, F., Anstis, S. (1998). The motion aftereffect: a modern perspective, Mit Press.
Maudlin, T. (2007). The metaphysics within physics. Oxford: Oxford University Press.
McTaggart, J.M.E. (1908). The unreality of time. Mind, 17(68), 457–474.
Mellor, D.H. (1998). Real time II. Routledge.
Miller, K., Holcombe, A., Latham, A.J. (2018). Temporal phenomenology: phenomenological illusion

versus cognitive error. Synthese.
Nishida, S. (2011). Advancement of motion psychophysics: review 2001–2010. Journal of Vision, 11(5),

11–11.
Nishida, S., Ledgeway, T., Edwards, M. (1997). Dual multiple-scale processing for motion in the human

visual system. Vision Research, 37(19), 2685–2698.
Norton, J.D. (2010). Time really passes. Humana. Mente: Journal of Philosophical Studies, 13, 23–24.
Pantle, A. (1992). Immobility of some second-order stimuli in human peripheral vision. Journal of the

Optical Society of America. A, 9(6), 863–867.
Paul, L.A. (2010). Temporal experience. The Journal of Philosophy, 107(7), 333–359.
Perry, J. (2001). Time, consciousness and the knowledge argument. In Oaklander, L., & Perry, J. (Eds.)

(pp. 81–93): Springer.
Phillips, I. (2014). Experience of and in time. Philosophy Compass, 9(2), 131–144.
Pötzl, O., & Redlich, E. (1911). Demonstration eines falles von bilateraler affektion beider occipitallappen.

Wiener Klinische Wochenschrift, 24, 517–518.
Price, H. (1996). Time’s arrow and Archimedes’ point: new directions for the physics of time. Oxford:

Oxford University Press.
Prosser, S. (2012). Why does time seem to pass? Philosophy and Phenomenological Research, 85(1),

92–116.
Prosser, S. (2013). Passage and perception. Noûs, 47(1), 69–84.
Prosser, S. (2016). Experiencing time. Oxford: Oxford University Press.
Putnam, H. (1967). Time and physical geometry. The Journal of Philosophy, 64(8), 240–247.
Rietdijk, C.W. (1966). A rigorous proof of determinism derived from the special theory of relativity.

Philosophy of Science, 33(4), 341–344.
Smart, J.J.C. (1949). The river of time. Mind, 58(232), 483–494.
Smart, J.J.C. (1980). Time and becoming. In Van Inwagen, P. (Ed.) Time and cause: essays presented to

Richard Taylor (pp. 3–15). Dordrecht: Reidel.
Tallant, J. (2010). A sketch of a presentist theory of passage. Erkenntnis, 73(1), 133–140.
Tye, M. (2018). Qualia. In Zalta, E.N. (Ed.) The Stanford encyclopedia of philosophy (Summer 2018 ed.)

Metaphysics Research Lab: Stanford University.
Vaina, L.M., & Cowey, A. (1996). Impairment of the perception of second order motion but not first order

motion in a patient with unilateral focal brain damage. Proceedings of the Royal Society of London B:
Biological Sciences, 263(1374), 1225–1232.

Vaina, L.M., & Soloviev, S. (2004). First-order and second-order motion: neurological evidence for neu-
roanatomically distinct systems. In The roots of visual awareness: a festschrift in honour of Alan
Cowey, volume 144 of progress in brain research (pp. 197–212): Elsevier.

Vaina, L., Makris, N., Kennedy, D., Cowey, A. (1998). The selective impairment of the perception of
first-order motion by unilateral cortical brain damage. Visual Neuroscience, 15(2), 333–348.

Wertheimer, M. (1912). Experimentelle studien über sehen von bewegung. Z Psychol Physiol Sinnesor-
gane, 61, 161–265.

European Journal for Philosophy of Science (2020) 10: 8 Page 23 of 24 8

http://www.ritsumei.ac.jp/akitaoka/index-e.html


Williams, D.C. (1951). The myth of passage. The Journal of Philosophy, 48(15), 457–472.
Zeki, S. (1991). Cerebral akinetopsia (visual motion blindness). Brain: A Journal of Neurology, 114(2),

811–824.
Zihl, J., Von Cramon, D., Mai, N. (1983). Selective disturbance of movement vision after bilateral brain

damage. Brain: A Journal of Neurology, 106(2), 313–340.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps
and institutional affiliations.

European Journal for Philosophy of Science (2020) 10: 88 Page 24 of 24


	Explaining temporal qualia
	Abstract
	Introduction
	Temporal passage and temporal qualia: two independent philosophical problems
	Passage realism
	Passage antirealism
	Eliminating passage-talk

	What is the problem of temporal qualia?
	`Temporal qualia' as an umbrella term
	Are temporal qualia representational?
	Temporal qualia and the explanatory gap
	What is the explanatory problem of temporal qualia?

	How (not) to explain temporal qualia
	Representational realism
	Inferential realism

	Abusing your illusion
	When temporal qualia are illusory
	Why illusions don't imply illusionism

	An appetite for reduction
	Understanding reductionism
	Pluralism about temporal qualia
	Motion blindness and temporal qualia

	Summing up
	References