David Hume (1711-1776) is unquestionably one of the most influential philosophers of the Modern period. Born in Edinburgh, Scotland, his philosophical works include A Treatise on Human Nature (1739), Essays, Moral and Political (2 vols., 1741-1742), An Enquiry Concerning Human Understanding (1748), and An Enquiry Concerning the Principles of Morals (1751). He also published a history of Great Britain and, posthumously, Dialogues Concerning Natural Religion.
Empiricism
Hume belongs to the tradition of British empiricism
that includes Francis Bacon (1561-1626), John Locke (1632-1704), and George
Berkeley (1685-1753). Common to this tradition is the view that knowledge
is founded upon sense-perception, which the human mind passively receives.
But whereas Locke and Berkeley believe that human knowledge can go beyond
sense-experience, Hume contends in the Introduction of his Treatise that
our knowledge is limited to sense-experience, and so offers an empiricism
that he argues is more consistent than those of his British predecessors.
Hume’s analysis of the contents of sense-experience
begins with the distinction between impressions and ideas. Impressions,
which include all our sensations and passions, are more forceful and lively
than ideas, which are “the faint images of these in thinking and reasoning”
(Treatise, p. 1). Ideas are epistemologically inferior to
impressions, and the secondary status that Hume gives them stands in marked
contrast to a long tradition in Western philosophy which asserts that universal
ideas—not singular sense impressions—are the proper objects of the human
intellect. Following Locke, Hume also distinguishes between
the simple and complex. Simple impressions and ideas, such as the
seeing or imagining of a particular shade of red, admit of no distinction
nor separation. Complex impressions and ideas, such as the seeing
or imagining of an apple, can be analyzed into their component parts.
Whereas all simple ideas are derived from and exactly represent simple
impressions, many complex ideas are not, and so their veracity must be
called into question. Hume remarks, “When we entertain, therefore,
any suspicion that a philosophical term is employed without any meaning
or idea (as it but too frequent) we need but enquire, from what impression
is that supposed idea derived? And if it be impossible to assign
any, this will serve to confirm our suspicion” (first Enquiry, sec.
II).
Hume proceeds to show that a number of complex
ideas in philosophy, such as the idea of an immaterial self as the core
of personal identity, fail to meet his empiricist criterion (see Treatise,
Book I, Part IV, sec. VI). But the most famous subject of his criticism
is the relation of cause and effect. Western philosophers and scientists
traditionally believed that to know something fully one must know the cause
upon which it necessarily depends. Hume argues that such knowledge
is impossible. He notes that the causal relationship provides the
basis for all reasonings concerning matters of fact; however, unlike the
relations of ideas explored by mathematics, no judgments that concern matters
of fact are necessarily true. This is because we can always imagine,
without contradiction, the contrary of every matter of fact (e.g., ‘the
sun will not rise tomorrow’ neither is nor implies a contradiction). Hume
adds that the causal relationship between any two objects is based on experience,
and is not known a priori (e.g., if Adam were created with perfect
rational faculties, prior to experience he still could not tell from the
properties of water that it would suffocate him.) Yet all that experience
establishes concerning causal relationships is that the cause is prior
in time to and contiguous with its effect. Experience cannot establish
a necessary connection between cause and effect, because we can imagine
without contradiction a case where the cause does not produce its usual
effect (e.g., we can imagine that a cue ball violently strikes another
billiard ball and then, instead of causing the billiard ball to move, the
cue ball bounces off it in some random direction). The reason why
we mistakenly infer that there is something in the cause that necessarily
produces its effect is because our past experiences have habituated us
to think in this way. That is, because we have seen in the past that
B frequently follows A and never occurs without it,
our mind associates B with A such that the presence of one
determines the mind to think of the other (see Treatise, Book I,
Part III; first Enquiry, sec. IV-V).
Ethical Theory
Hume maintains that moral distinctions are
derived from feelings of pleasure and pain of a special sort, and not—as
held by many Western philosophers since Socrates—from reason. Working
from the empiricist principle that the mind is essentially passive, Hume
argues that reason by itself can never prevent or produce any action or
affection. But since morals concerns actions and affections, it cannot
be based on reason. Furthermore, reason can influence our conduct
in only two ways. First, reason can inform us of the existence of
something which is the proper object of a passion, and thereby excite it.
Second, reason can deliberate about means to an end that we already desire.
But should reason be in error in either of these areas (e.g., by mistaking
an unpleasant object for one which is pleasant, or by mistakenly selecting
the wrong means to a desired end), it is not a moral but an intellectual
failing. As a final point, Hume argues for a distinction between
facts and values. According to Hume, one cannot infer conclusions
about what ought or ought not to be the case based on premises of what
is or is not (see Treatise, Book III, Part I, sec. 1).
Since moral distinctions are not based on
reason, Hume infers that they are based on sentiments that are felt by
what he calls a “moral sense.” When we describe an action, sentiment,
or character as virtuous or vicious, it is because its view causes a pleasure
or pain of a particular kind. Hume is well aware that not all pleasures
and pains (e.g., the pleasure of drinking good wine) lead to moral judgments.
Rather, it is “only when a character is considered in general, without
reference to our particular interest, that it causes such a feeling or
sentiment, as denominates it morally good or evil” (Treatise, Book
III, Part I, sec. 2). Finally, Hume argues that even though moral
distinctions are based on feelings, this does not lead to moral relativism.
For the general moral principles and the moral sense faculty that recognizes
them are common to all human beings (see second Enquiry, “A Dialogue”).
Limitations of space prevent even a cursory sketch of Hume’s treatment of other philosophical questions, such as whether God exists and whether humans have free will and an immortal soul. But the devastating impact of Hume’s empiricism on traditional metaphysics is succinctly summarized by the closing lines of his first Enquiry. “If we take in our hand any volume of divinity or school metaphysics . . . let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: for it can contain nothing but sophistry and illusion.”
Shane Drefcinski
UW-Platteville