Microsoft Word - Successful visual epistemic representation.docx Successful  Visual  Epistemic  Representation     1    Successful  Visual  Epistemic  Representation   Agnes  Bolinska     Abstract:  In  this  paper,  I  characterize    visual  epistemic  representations  as  concrete  two-­‐  or   three-­‐dimensional  tools  for  conveying  information  about  aspects  of  their  target  systems  or   phenomena  of  interest.  I  outline  two  features  of  successful  visual  epistemic  representation:   that  the  vehicle  of  representation  contain  sufficiently  accurate  information  about  the   phenomenon  of  interest  for  the  user’s  purpose,  and  that  it  convey  this  information  to  the   user  in  a  manner  that  makes  it  readily  available  to  her.  I  argue  that  actual  epistemic   representation  may  involve  tradeoffs  between  these  features  and  is  successful  to  the   extent  that  they  are  present.     1.  Introduction   How  do  scientists  gain  information  about  a  physical  system?  The  most   straightforward  way  would  be  to  examine  the  system  using  their  unaided  senses.  But  the   senses  often  do  not  suffice  for  observation  because  the  system  is  too  small  (like  a   molecule),  too  distant  (like  a  star),  too  dispersed  (like  a  population),  or  otherwise   imperceptible.  In  such  cases,  scientists  may  use  instruments  to  facilitate  their  investigation.   But  once  they  have  exhausted  all  observational  avenues  –  once  they  have  done  everything   possible  to  gain  information  from  the  system  itself  –  they  usually  have  only  completed  the   first  phase  of  their  investigation.  For  scientists  are  generally  not  interested  in  particular   Successful  Visual  Epistemic  Representation     2   measurements,  but  in  generalizations  or  patterns  that  can  be  inferred  from  them.1  These   patterns,  which  I  will  refer  to  as  phenomena  of  interest,  are  rarely  accessible  through  direct   observation.2  So  the  question  is:  once  all  available  observational  data  has  been  acquired,   how  can  scientists  use  a  vehicle  of  representation  –  an  entity  physically  separate  from  the   system  it  represents  –  as  a  tool  for  gaining  information  about  the  phenomenon  of  interest?       The  answer,  I  will  argue,  is  by  representing  the  system  in  a  way  that  makes  these   patterns  perspicuous  to  the  user.  I  call  vehicles  of  representation  that  are  used  as  tools  for   gaining  information  about  phenomena  of  interest  epistemic  representations.  As  I  will  show,   these  include  not  only  scientific  representations,  but  also  other  representations  that  are   used  in  similar  ways  outside  of  scientific  practice.  By  bringing  the  features  of  interest  to   the  fore,  an  epistemic  representation  unlocks  for  the  user  a  dimension  of  access  to  the   phenomenon  of  interest  that  she  wouldn’t  otherwise  have.       There  are  two  sorts  of  contexts  in  which  epistemic  representations  may  be  used:   those  in  which  little  or  nothing  is  known  about  the  phenomenon  of  interest,  and  the   representation  functions  as  an  investigative  tool;  and  those  in  which  the  creator  of  the   representation  already  understands  the  phenomenon  of  interest  fairly  well  and  uses  it  as  a   tool  for  conveying  information  about  this  phenomenon  via  testimony.  In  this  paper,  I  focus   on  the  latter  sort  of  context  and  limit  my  attention  to  two-­‐  and  three-­‐dimensional  visual   representations.  I  investigate  the  features  in  virtue  of  which  such  representations  convey                                                                                                                   1  The  point  that  scientists  tend  to  be  interested  in  patterns  or  regularities  has  been  nicely  articulated  by   Batterman  (2009,  pp.  429-­‐30).   2  Why  this  is  so  will  become  clear  shortly  through  the  consideration  of  examples  (Section  2).   Successful  Visual  Epistemic  Representation     3   information  to  their  users  about  phenomena  of  interest  that  they  wouldn't  otherwise  have.   That  is,  I  determine  the  features  of  successful  representation  for  these  kinds  of  cases.3         In  order  to  understand  what  is  required  for  successful  visual  epistemic   representation,  two  questions  must  be  addressed.  First,  what  kind  of  information  ought   the  vehicle  of  representation  contain,  and  what  is  required  for  it  to  contain  this   information?  Second,  how  is  this  information  effectively  conveyed  to  the  user?  I  will  argue   that  an  epistemic  representation  is  successful  to  the  extent  that  it  contains  sufficiently   accurate  information  about  the  phenomenon  of  interest  for  the  user’s  purpose  (Section  3)   and  is  able  to  convey  this  information  to  the  user  in  a  manner  that  makes  it  readily   available  to  her  (Section  4).  I  will  show  that  because  visual  epistemic  representation  often   involves  tradeoffs  between  these  two  features,  the  success  of  such  representation  is   determined  by  how  well  they  are  balanced  (Section  5).  But  I  will  begin  (Section  2)  by   outlining  three  examples  of  successful  visual  epistemic  representation  and  showing  that   they  share  two  general  features  that  inform  the  more  specific  features  considered  in   Sections  3  and  4:  they  are  user-­‐  and  purpose-­‐specific.     2.  Examples  and  general  features   User-­‐  and  purpose-­‐specificity  are  widely  accepted  features  that  comprise  a  central   part  of  several  accounts  of  scientific  representation  (cf.  Bailer-­‐Jones,  2003;  Giere,  2004,   2009;  Mäki,  2009;  Teller,  2001).  I  highlight  these  features  here  to  provide  a  foundation                                                                                                                   3  Many  authors  (cf.  Callender  &  Cohen,  2006;  Contessa,  2007;  Suárez,  2004)  focus  on  understanding  mere  –   that  is,  not  necessarily  true  or  accurate  –  representation.  I  think  that  understanding  successful  epistemic   representation  (which,  as  I  will  show,  isn't  just  true  or  accurate  representation)  can  also  guide  us  in   understanding  'mere'  representation.  While  a  full  discussion  of  why  this  is  so  is  beyond  the  scope  of  this   paper,  it  will  become  apparent  once  the  account  has  been  put  forth.   Successful  Visual  Epistemic  Representation     4   from  which  the  remainder  of  my  analysis  may  be  developed.  By  taking  the  user-­‐  and   purpose-­‐specificity  of  epistemic  representations  as  a  starting  point,  we  may  then  ask   further  questions  about  these  features,  thereby  better  coming  to  understand  visual   epistemic  representation.  In  which  ways,  precisely,  are  such  representations  user-­‐  and   purpose-­‐specific?  In  virtue  of  what  are  they  so?     In  this  section,  I  will  present  three  examples  of  successful  visual  epistemic   representation,  in  each  case  identifying  the  phenomenon  of  interest,  indicating  the  sense   in  which  it  is  inaccessible  to  its  user(s)  through  direct  examination  of  the  physical  system   in  question,  and  highlighting  the  ways  in  which  the  representation  is  successful  only  for   certain  users  and  for  specific  purposes.     The  first  example  is  adapted  from  Suárez  (2004).  Suppose  we  want  to  represent  a   system  consisting  of  two  ships  travelling  along  the  sea  using  two  pens  and  a  piece  of  paper.   Let  us  further  assume  that  the  representation  is  used  in  the  context  of  a  conversation   between  the  captain  of  one  of  the  ships  and  her  friend.  To  help  recount  the  highlights  of   her  last  voyage,  the  captain  might  move  the  two  pens  along  the  paper  to  demonstrate,  for   instance,  a  maneuver  she  had  to  perform  to  avoid  colliding  with  another  ship  that  had   strayed  off  course.  In  this  example,  the  phenomenon  of  interest  consists  of  the  relative   trajectories  of  the  ships.  It  is  inaccessible  to  the  captain’s  friend  because  he  was  not   present  to  witness  her  collision-­‐avoiding  maneuver.  While  the  intended  user  of  the  pens-­‐ on-­‐paper  system  is  the  captain’s  friend,  it  would  be  suitable  for  many  other  users  as  well,   since  little  background  knowledge  is  required  to  understand  the  relative  motions  of  the   ships.  The  purpose  of  the  pens-­‐on-­‐paper  system  is  to  help  the  captain  relay  certain  parts  of   her  voyage  to  her  friend.     Successful  Visual  Epistemic  Representation     5   A  second  example  of  a  successful  epistemic  representation  is  the  iconic  map  of  the   London  Underground  transit  system.4  Originally  designed  by  draftsman  Harry  Beck  in   1933  and  modelled  after  a  circuit  diagram,  the  network  of  railway  lines  and  stations  that   comprise  the  Underground  is  depicted  as  an  orderly  array  of  intertwined  coloured  lines,   along  which  lie  evenly-­‐spaced  marks  labelled  with  station  names,  with  white  circles   replacing  these  marks  to  designate  interchange  stations.  Included  with  the  map  are  keys   that  tell  users  how  to  interpret  each  of  its  features  (Figure  1).  With  the  aid  of  this  map,   approximately  three  million  daily  users  of  the  Underground  are  able  to  navigate  this   expansive  system.  The  phenomenon  of  interest  varies  between  users:  for  each,  it  is  the  set   of  the  possible  routes  connecting  the  stations  between  which  she  wishes  to  travel.  These   routes  are  inaccessible  to  her,  since  while  she  could  in  principle  ride  the  Underground  in   various  directions  to  determine  which  one  connects  her  to  her  destination  station,  this   would  be  extremely  impractical.  Because  the  map  of  the  London  Underground  is  intended   for  use  by  a  broad  range  of  people  with  a  variety  of  backgrounds  and  cognitive  capacities,   it  is  designed  to  cater  universally  to  human  users.5  The  purpose  of  the  map  is  to  determine   the  most  efficient  route  from  one  station  to  another.                                                                                                                       4  This  example  is  also  discussed  by  Contessa  (2007),  Hoover  (2012)  and  Bolinska  (2013).     5  This  is  not  to  say  that  no  training  whatsoever  is  required  –  users  must  be  familiar  with  the  conventions   involved  in  reading  maps  –  but  that  the  level  of  training  required  is  relatively  low  and  fairly  universally  held   in  many  parts  of  the  world.     Successful  Visual  Epistemic  Representation     6     Figure  1:  The  complete  London  Underground  map.  Note  the  even  spacing  of  labelled  stations,  colouring  of   railway  lines  (with  key  in  the  bottom  right  corner)  and  white  circles  indicating  interchange  stations.     Finally,  a  third  example  of  a  successful  epistemic  representation  is  a  three-­‐ dimensional  model  of  a  macromolecule  like  DNA  or  protein.  The  phenomenon  of  interest   in  this  case  is  the  structure  of  the  molecule,  viz.  its  three-­‐dimensional  shape,  including   bond  types,  lengths  and  angles  between  constituent  atoms.  This  structure  is  otherwise   inaccessible  to  the  user:  it  is  not  directly  observable  even  using  techniques  like  x-­‐ray   diffraction  photography,  since  the  images  produced  using  such  techniques  must  be   interpreted  to  yield  putative  structures,  and  the  process  of  interpretation  can  yield  results   that  are  often  ambiguous  or  misleading.6  Unlike  the  map  of  the  London  Underground,  a   molecular  model's  key  is  implicit,  so  users  must  be  told  which  features  of  the  model   correspond  to  which  features  of  a  molecule,  e.g.  that  white  balls  stand  of  hydrogen  atoms,   black  for  carbon,  etc.  While  any  user  who  understands  this  convention  may  grasp  the                                                                                                                   6  The  problem  of  determining  molecular  structure  from  x-­‐ray  diffraction  photographs  in  the  mid-­‐twentieth   century  was  notoriously  difficult.  See  Olby  (1974)  and  Judson  (1996).   Successful  Visual  Epistemic  Representation     7   structure  as  a  whole,  molecular  models  are  most  useful  for  one  with  training  in  molecular   biology  in  the  pursuit  of  further  aims.    For  instance,  such  a  user  may  rely  on  the  knowledge   of  the  structure  she  gains  from  the  model  to  determine  the  function  of  the  molecule  or  how   it  will  interact  with  other  molecules.  Thus,  the  purpose  for  which  the  model  is  used  often   extends  beyond  simply  learning  about  molecular  structure.     3.  Containing  sufficiently  accurate  information     With  these  examples  in  hand,  we  may  now  turn  to  the  more  specific  features  of   successful  epistemic  representation,  each  of  which  depends  on  the  phenomenon  of   interest,  the  user,  and  the  purpose  for  which  the  representation  is  used.  The  aim  of   employing  epistemic  representations  is  to  learn  about  an  aspect  of  the  target  system,  the   phenomenon  of  interest.  But  as  I  showed  in  the  previous  section,  users  often  don’t  seek  to   learn  about  this  phenomenon  for  its  own  sake,  but  rather  to  use  what  they  learn  for  some   further  purpose.  How  accurate  the  information  they  gain  need  be  depends  on  what  this   purpose  is.         3.1  When  is  information  sufficiently  accurate?     In  the  pens-­‐on-­‐paper  example  the  user  is  interested  in  the  ships’  relative   trajectories  as  an  aid  to  understanding  the  relevant  parts  of  the  captain’s  voyage.  Thus,   only  very  general  information  about  the  trajectories  need  be  contained  in  the  pens-­‐on-­‐ paper  representation.  For  instance,  let  us  assume  that  one  ship  was  on  a  head-­‐on  collision   course  with  the  other,  and  the  other  veered  off  to  the  right  just  in  time  to  avoid  the   collision.  This  information  should  be  contained  in  the  vehicle  of  representation,  but  the   Successful  Visual  Epistemic  Representation     8   vehicle  need  not  accurately  portray  the  precise  angle  of  approach  between  the  ships’   trajectories,  nor  the  angle  at  which  the  second  ship  veered  off  course  to  avoid  the  collision.   So  long  as  the  more  general  information  is  contained  in  the  vehicle  of  representation,  the   vehicle  may  serve  its  function  as  an  aid  in  the  telling  of  the  story.     The  map  of  the  London  Underground  is  used  with  the  aim  of  determining  the  most   efficient  journey  between  stations  selected  by  its  users;  thus,  it  should  be  possible  to   determine  the  most  efficient  route  between  any  two  stations  in  the  network  using  the  map.   In  order  to  be  used  for  this  purpose,  the  map  must  contain  information  about  the  relative   locations  of  stations  along  each  line,  including  information  about  the  locations  of   interchange  stations  at  which  users  may  switch  lines.  It  need  not  contain  information   about  other  features  of  the  network,  such  as  its  position  with  respect  to  above-­‐ground   streets  or  the  distances  between  stations  to  represent  the  network  faithfully  for  its  users’   purposes.7  As  in  the  ships-­‐on-­‐sea  example,  being  more  accurate  in  this  respect  does  not   contribute  to  the  success  of  the  epistemic  representation.  In  fact,  as  we  will  see  in  Section   5,  it  could  even  detract  from  its  success  if  increased  accuracy  comes  at  the  price  of  a   reduction  in  the  ease  with  which  this  information  may  be  conveyed  to  the  user.     It  may  be  objected  here  that  it's  not  the  case  that  the  map  of  the  London   Underground  represents  features  such  as  distance  between  stations  inaccurately:   distances  between  stations  are  omitted  from  the  map,  not  misrepresented,  since  the  map's   content  is  determined  by  its  intended  use.  This  objection  raises  an  important  point  about                                                                                                                   7  We  may  assume  that  the  distances  between  stations  are  sufficiently  similar  to  one  another  that  in  each  case   the  most  direct  route  between  stations  –  that  requiring  the  fewest  number  of  stops  and  changes  between   lines  –  will  be  the  quickest.   Successful  Visual  Epistemic  Representation     9   the  relationship  between  how  much  information  is  contained  in  a  representation  and  how   accurate  that  information  is.       In  general,  the  fact  that  one  representation  contains  less  information  than  another   does  not  render  it  less  accurate.  'Smith  lives  in  Canada'  is  less  informative  than  'Smith  lives   in  Toronto',  yet  both  sentences  may  be  equally  accurate,  e.g.  if  Smith  lives  in  Toronto,   Canada,  or  the  former  may  be  more  accurate  than  the  latter,  e.g.  if  Smith  lives  in   Mississauga,  a  suburb  of  Toronto.  But  in  the  case  of  epistemic  representation,  we  are   concerned  not  with  accuracy  simpliciter,  but  in  accuracy-­for-­a-­purpose.  And  accuracy-­‐for-­‐ a-­‐purpose  is  closely  related  to  the  amount  of  information  a  representation  contains.  Recall   that  epistemic  representations  are  used  to  convey  information  not  about  the  target  system   in  general,  but  about  the  phenomenon  of  interest;  moreover,  users  are  interested  in  gaining   this  information  for  a  particular  purpose.     If  a  representation  is  not  sufficiently  information-­‐rich  –  if  it  omits  bits  of   information  that  are  necessary  for  understanding  the  phenomenon  of  interest  for  that   purpose  –  then  it  cannot  represent  the  phenomenon  of  interest  sufficiently  accurately  for   that  purpose.  The  map  of  the  London  Underground  omits  information  about  distances   between  stations  –  it  represents  these  stations  as  evenly  spaced,  but  users  are  not  meant   to  infer  from  this  feature  of  the  map  that  distances  between  stations  are,  in  fact,  equal.   Suppose  the  map  also  omitted  information  about  where  the  lines  intersect,  simply   depicting  them  in  parallel  with  one  another.  The  omission  of  this  crucial  information   would  render  this  map  not  only  less  informative,  but  also  less  accurate,  given  a  user's   interest  in  getting  from  any  one  station  in  the  system  to  any  other.  Key  pieces  of   information,  such  as  the  places  in  which  the  lines  intersect,  must  be  contained  in  the  map   Successful  Visual  Epistemic  Representation     10   in  order  for  it  to  accurately  portray  routes  between  stations  for  this  purpose.  So  the   accuracy  of  an  epistemic  representation  –  that  is,  its  accuracy-­‐for-­a-­purpose  –  depends  in   part  on  it  containing  a  sufficient  amount  of  information  to  accurately  represent  the   phenomenon  of  interest  for  the  user's  purpose.     Finally,  in  the  examples  of  molecular  modelling,  the  target  systems  of  the   representations  are  molecules  like  protein  or  DNA,  while  the  phenomena  of  interest  are   the  structures  of  these  molecules.  The  purpose  of  gaining  information  about  these   structures  is  often  to  enable  further  research  into  molecular  function.  For  instance,   knowing  the  structure  of  DNA  readily  suggested  a  copying  mechanism  for  this  molecule  of   inheritance.  Thus,  unlike  in  the  previous  two  examples,  where  only  general  and  relative   positions  of  the  relevant  objects  are  required  for  users'  purposes,  fairly  specific   information  about  atomic  positions  and  bond  lengths  and  angles  needs  to  be  contained  in   the  vehicle  of  representation  in  these  cases  to  enable  further  investigation.  Without  such   specific  information,  one  cannot,  for  instance,  determine  what  accounts  for  DNA's  stability   or  how  it  may  be  'unzipped'  and  replicated.     3.2  How  does  a  vehicle  contain  information?     We’ve  now  established  which  information  need  be  contained  in  a  vehicle  of  visual   representation  in  order  for  that  vehicle  to  epistemically  represent  its  target  system:   information  about  the  phenomenon  of  interest  that  is  sufficiently  accurate  for  its  user's   purpose.  We  will  now  turn  to  another  question:  how  does  a  vehicle  come  to  contain  that   Successful  Visual  Epistemic  Representation     11   information?  While  the  term  ‘information’  may  be  used  differently  in  other  contexts,8  here   we  are  concerned  with  semantic  information,  the  sense  in  which  this  term  is  perhaps  most   commonly  used.  This  is  the  sense  in  which  a  newspaper  contains  information  about   current  events,  a  map  contains  information  about  the  layout  of  a  city,  and  a  model  contains   information  about  the  physical  system  it  represents.       Semantic  information  may  be  either  natural  or  non-­‐natural  information.9  Natural   information  is  a  product  of  certain  naturally  occurring  correlations.  Examples  include   smoke  carrying  the  information  that  there  is  fire  and  rings  on  a  tree  carrying  information   about  the  tree’s  age.  We  will  generally  not  be  concerned  with  natural  information,  since   most  vehicles  of  epistemic  representation,  and  particularly  scientific  models,  are  human   constructs.  Thus,  ‘information’  will  here  be  used  to  refer  to  non-­‐natural  information.         An  artefact  may  contain  non-­‐natural  information  by  convention.  For  example,  in  a   weather  forecast,  a  picture  of  a  cloud  and  rain  labelled    ‘80%'  contains  the  information  that   there  is  an  80%  chance  of  showers,  and  a  sign  that  says  ‘Gift  shop  downstairs’  contains  the   information  that  the  gift  shop  is  downstairs.  In  these  examples,  the  conventions  via  which   the  vehicles  contain  information  are  known  to  most  people  who  encounter  them.  But  this   need  not  be  the  case.  Before  arriving  at  a  party,  I  might  establish  with  my  companion  that   either  of  us  uttering  the  sentence  ‘This  wine  is  fantastic’  indicates  his  or  her  desire  to  leave.   In  this  case,  ‘This  wine  is  fantastic’  contains  the  information  that  its  utterer  would  like  to   leave  the  party  (provided  that  the  utterer  is  either  my  companion  or  I).                                                                                                                   8  For  instance,  Fisher  information,  Shannon  information,  Kolmogorov  complexity  and  quantum  information   each  refer  to  different  notions  of  information.  For  a  survey  of  how  these  notions  are  used  and  related  to  one   another,  see  Adriaans  (2013).   9  Grice  (1957)  made  the  distinction  between  natural  and  non-­‐natural  meaning;  Piccinini  and  Scarantino   (2010)  have  extended  this  distinction  to  information.     Successful  Visual  Epistemic  Representation     12     The  information  contained  in  a  vehicle  of  representation  need  not  be  true.  A  sign   that  says  ‘Gift  shop  downstairs’  contains  the  information  that  the  gift  shop  is  downstairs   even  if,  as  a  matter  of  fact,  it  has  been  relocated  to  the  second  floor;  in  this  case,  the  sign   contains  false  information.10  Similarly,  suppose  I  really  like  the  wine  being  served  at  the   party,  and  carelessly  remark,  ‘This  wine  is  fantastic’,  even  though  I’m  having  a  good  time   and  don’t  yet  want  to  leave.  In  this  case,  the  sentence  nevertheless  contains  the   information  that  I  want  to  leave  the  party,  but  this  information  is  false.   Because  a  vehicle  of  representation  may  carry  information  by  convention,  is  it  the   case  that  anything  may  carry  information  about  anything  else,  just  as  anything  may  denote   anything  else?  As  noted  earlier,  information  is  a  multifarious  concept;  here  we  are   restricting  our  attention  to  the  sense  in  which  information  can  be  contained  in  a  vehicle  of   representation  about  an  aspect  of  a  target  system,  not,  for  instance,  the  sense  in  which   information  is  carried  in  our  genetic  code,  or  that  in  which  it  is  stored  in  computer   databases.  Neither  the  information  contained  in  our  genetic  code  nor  that  stored  in   computer  databases  is  directly  accessible  to  a  user  who  consults  these  things  directly.   Rather,  a  complex,  multi-­‐step  process  is  necessary  for  its  extraction.  A  DNA  molecule  must   first  be  sequenced;  the  sequence  must  then  be  decoded  by  someone  with  the  requisite   training  and  experience.  A  computer’s  hard  drive  doesn’t  issue  information  about  its   contents  directly,  but  must  be  accessed  using  particular  software  and  hardware.                                                                                                                     10  Many  authors  (Barwise  &  Seligman,  1997;  Floridi,  2004,  2005;  Graham,  1999;  Grice,  1989)  take  truth  to   be  a  requirement  for  information.  For  instance,  Dretske  contends  that  “false  information  and  mis-­‐ information  are  not  kinds  of  information  –  any  more  than  decoy  ducks  and  rubber  ducks  are  kinds  of  ducks”   (1981,  p.  45).  However,  this  requirement  fails  to  accommodate  many  of  the  ways  in  which  'information'  is   used.  Moreover,  the  authors  who  hold  this  position  have  failed  to  give  a  good  argument  for  why  it  should  be   adopted  (Scarantino  &  Piccinini,  2010).   Successful  Visual  Epistemic  Representation     13   In  contrast,  it  only  makes  sense  to  speak  of  a  vehicle  of  epistemic  representation  –  a   tool  for  conveying  information  –  as  containing  information  if  that  information  is  available   to  the  user  when  she  consults  the  vehicle.  The  sentence  'This  wine  is  fantastic'  contains  the   information  that  its  utterer  wants  to  leave  the  party:  once  the  convention  has  been   established,  the  person  who  hears  this  sentence  may  grasp  that  its  utterer  wants  to  leave   the  party.  ‘This  wine  is  fantastic’  does  not  contain  the  information  that  its  utterer  wants  to   leave  the  party  because  he  or  she  is  tired,  since  this  further  bit  of  information  was  not   included  in  the  convention  when  it  was  established.  If  my  companion  utters  ‘This  wine  is   fantastic’  with  a  yawn  and  vacant  stare,  I  might  infer  that  he  wants  to  leave  the  party   because  he  is  tired,  but  this  inference  would  be  based  on  the  information  the  sentence   contains  together  with  information  obtained  from  the  yawn  and  vacant  stare   accompanying  its  utterance.     Of  course,  if  my  companion  and  I  were  to  establish  such  a  convention  at  the  outset,   ‘This  wine  is  fantastic’  would  contain  the  information  that  the  utterer  of  the  sentence   wants  to  leave  the  party  because  he  or  she  is  tired.  In  this  case,  if  I  heard  my  companion   say  'This  wine  is  fantastic',  I  could  immediately  infer  that  he  wants  to  leave  the  party   because  he  is  tired,  even  absent  the  yawn  and  vacant  stare.  This  sentence  could  also  be   made  to  contain  more  information  than  this,  such  as  that  its  utterer  wants  to  leave  the   party  because  he  or  she  is  tired  and  has  become  bored  with  the  conversation.  But  the   amount  of  information  that  ‘This  wine  is  fantastic’  can  contain  is  constrained  by  the   limitations  of  its  users'  memories.  So,  for  instance,  it  cannot  contain  information  about  the   names  and  birthdays  of  each  of  the  party’s  guests:  even  if  I  stipulate  that  'This  wine  is   fantastic'  contains  the  information  that  John  Smith’s  birthday  is  on  February  24th  and  Anne   Successful  Visual  Epistemic  Representation     14   MacDonald’s  is  on  June  2nd  and  so  on  for  each  of  the  party’s  guests,  the  only  people  familiar   with  the  convention  –  my  companion  and  I  –  are  unable  to  extract  that  information  from   the  sentence.11  Thus,  there  is  no  meaningful  sense  in  which  this  vehicle  really  does  contain   that  information.   In  general,  the  more  discernable  subcomponents  a  vehicle  has,  the  more   information  it  may  contain.  A  discernable  subcomponent  is  a  part  of  the  vehicle  that  can  be   distinguished  from  other  parts  by  its  user,  and  what  constitutes  a  discernable   subcomponent  in  each  case  depends  on  the  means  of  representation  and  the  user.  For   example,  each  of  the  pens  and  the  piece  of  paper  are  discernable  subcomponents  of  the   pens-­‐on-­‐paper  system,  but  an  arbitrarily  chosen  point  on  the  blank  piece  of  paper  is  not,   since  it  can’t  be  distinguished  by  an  ordinary  user  from  the  rest  of  the  paper.12     This  is  important  because  it  precludes  certain  vehicles  from  counting  as  successful   epistemic  representations  in  a  given  set  of  circumstances.  For  instance,  consider  an   alternative  to  the  pens-­‐on-­‐paper  representation,  the  paper-­‐on-­‐pens  system,  in  which  a   blank  piece  of  paper  represents  the  ship  trajectories  and  two  pens  represent  the  surface  of   the  sea.  While  such  a  system  may  certainly  denote  the  ships-­‐on-­‐sea  system,  it  cannot  be  an   epistemic  representation  of  that  system.  For  there  is  no  genuine  sense  in  which   information  about  the  individual  trajectories  of  the  ships  can  be  conveyed  to  a  user                                                                                                                   11  John  Kulvicki  (2010)  argues  that  more  complex  or  detailed  information  can  be  contained  in  a  fairly  simple   vehicle  of  representation,  but  may  not  be  ‘extractable’  from  that  vehicle.  For  instance,  the  information  that  its   target  is  square  is  extractable  from  the  representation  ‘square’;  however,  ‘square’  also  contains  the   information  that  its  target  has  four  sides  of  equal  lengths  and  right  internal  angles,  but  this  information  is   available  only  via  an  inference.  In  contrast,  I  am  concerned  with  information  that  is  contained  in  a  vehicle  of   representation  and  available  to  the  user  either  immediately  from  the  vehicle  or  via  this  kind  of  direct   inference.  Thus,  my  usage  of  ‘extractable’  differs  from  his  more  specific  sense  of  the  term.   12  There  may  be  more  than  one  way  to  individuate  subcomponents,  but  this  will  not  be  important  for  our   purposes,  as  will  become  clear  shortly.     Successful  Visual  Epistemic  Representation     15   consulting  the  blank  piece  of  paper;  as  Suárez  points  out,  such  a  representation  “seems   counterintuitive  and  unnatural”  (2004,  p.  772).     To  see  why,  let  us  consider  in  more  detail  how  the  captain  might  use  the  paper-­‐on-­‐ pens  system  to  represent  the  ships-­‐on-­‐sea  system  in  her  recounting  of  the  details  of  her   voyage.  The  general  strategy  would  be  to  stipulate  that  the  paper  represents  the   trajectories  of  the  ships  and  the  pens  represent  the  surface  of  the  sea  before  recounting   these  events.  Then,  upon  reaching  the  point  in  her  story  where  she  performs  the  collision-­‐ avoiding  maneuver,  she  could  simply  gesture  towards  the  paper-­‐on-­‐pens  system.  In  order   to  stipulate  that  the  paper  represents  the  trajectories  of  the  ships  and  the  pens  the  surface   of  the  sea,  the  captain  would  have  to  somehow  get  her  friend  to  understand  what  these   trajectories  looked  like,  either  by  describing  them  ('I  was  heading  due  north  when  I   noticed  a  ship  coming  from  port  side  up  ahead…'),  or  tracing  the  trajectories  with  her   hands  in  the  air,  or  even  using  the  pens  to  trace  them  on  the  paper  (!)  prior  to  reversing   the  representational  arrangement.  Once  this  was  done,  she  could  then  use  the  paper  to   represent  the  trajectories  of  the  ships  and  the  pens  the  surface  of  the  sea.  But  this  would   be  an  odd  thing  to  do  at  this  stage,  since  all  of  the  work  required  to  convey  information   about  the  trajectories  would  already  have  been  completed  in  the  earlier  stipulation  of  the   representational  arrangement.  When  the  captain  reached  the  part  of  her  story  in  which   she  describes  her  collision-­‐avoiding  maneuver,  gesturing  towards  the  paper  to  represent   the  trajectories  of  the  ships  would  be  superfluous;  the  captain  could  just  as  easily  say  'And   that’s  when  I  performed  that  maneuver  I  described  earlier'  instead.  Thus,  the  paper-­‐on-­‐ pens  system  cannot  be  used  as  an  epistemic  representation  of  the  ships-­‐on-­‐sea  system   because  it  does  not  have  the  resources  to  individuate  the  relative  trajectories  of  two  ships.   Successful  Visual  Epistemic  Representation     16   The  paper  is  a  single  uniform  object;  at  least  two  distinct  objects  are  required  to  convey   information  about  these  trajectories.       Each  of  our  examples  of  successful  epistemic  representation  contains  information   about  the  phenomenon  of  interest  because  it  contains  a  sufficient  number  of   subcomponents,  each  of  which  carries  more  specific  information  about  subcomponents  of   this  phenomenon.  In  the  ships-­‐on-­‐sea  system,  these  are  the  individual  ship  trajectories;   the  trajectory  of  each  pen  in  the  pens-­‐on-­‐paper  system  and  the  positions  of  these   trajectories  with  respect  to  one  another  convey  to  the  user  information  about  the   phenomenon  of  interest.       Similarly,  in  order  for  the  map  of  the  London  Underground  to  be  able  to  carry   information  about  the  most  efficient  routes  between  stations,  it  must  carry  several  specific   bits  of  information  that  are  necessary  for  making  this  determination.  In  particular,  it  must   carry  information  about  the  relations  between  lines  –  where  they  intersect,  allowing  users   to  travel  between  them  –  and  information  about  which  stations  are  located  along  each  line   and  in  which  order.  The  map  contains  features  that  are  responsible  for  carrying  each  of   these  bits  of  information.  The  railway  lines  of  the  London  Underground  system  are   represented  as  distinctly  coloured  lines  on  the  map;  interchange  stations  are  labelled  with   a  white  circle  overlapping  the  lines  between  which  the  user  may  travel;  and  individual   stations  are  represented  by  protrusions  along  each  line  labelled  with  station  names,  the   order  of  the  stations  along  the  lines  in  the  map  reflecting  the  order  of  the  stations  in  the   Underground  system.       Finally,  in  order  to  convey  to  the  user  information  about  molecular  structure  as  a   whole,  molecular  models  must  contain  specific  information  about  positions  of  particular   Successful  Visual  Epistemic  Representation     17   atoms  and  the  lengths  and  angles  of  the  bonds  that  join  them.  This  information  is   contained  in  the  pieces  representing  atoms  and  bonds,  and  the  ways  in  which  these  pieces   are  connected  to  one  another.   In  this  section,  I  have  argued  that  human  cognitive  and  perceptual  capacities   impose  limits  on  the  amount  of  information  a  vehicle  may  contain  about  its  target  system:   users  must  be  able  to  extract  information  from  the  representation,  and  they  must  be  able   to  distinguish  between  subcomponents  of  the  vehicle  which  stand  for  subcomponents  of   the  target  system.  But  while  a  vehicle's  containing  information  depends  in  part  on  the   possibility  of  using  it  to  convey  that  information,  vehicles  of  representation  nevertheless   differ  with  respect  to  how  well  they  convey  information  about  the  phenomenon  of  interest   to  their  users.  The  extent  to  which  this  information  is  conveyed  is  a  second  important   feature  of  successful  epistemic  representation.  In  the  next  section,  we  will  examine  the   notions  of  syntactic  and  semantic  salience,  the  features  that  make  information  cognitively   available  to  users,  and  thus  contribute  to  how  easily  information  is  conveyed.     4.  Conveying  information     In  order  for  the  information  contained  in  a  vehicle  of  epistemic  representation  to  be   effectively  conveyed  to  its  user,  it  must  be  readily  accessible  to  her.  In  this  section,   following  Kulvicki  (2010),  I  identify  two  features  that  contribute  to  this  ready  access:  the   syntactic  salience  of  subcomponents  and  the  semantic  salience  of  the  phenomenon  of   interest.  Because  both  come  in  degrees,  information  is  effectively  conveyed  to  a  user  to  the   extent  that  they  are  present.     Successful  Visual  Epistemic  Representation     18   4.1  Syntactic  salience  of  subcomponents   The  success  of  visual  epistemic  representation  depends  in  part  on  the  extent  to   which  a  feature  of  the  vehicle  of  representation  that  carries  information  is  perceptually   prominent  or  syntactically  salient  for  a  user  (Kulvicki,  2010).  When  the  trajectories  of  the   ships  in  the  ships-­‐on-­‐sea  system  are  represented  by  the  trajectories  of  the  pens  in  the   pens-­‐on-­‐paper  system,  they  very  clearly  stand  out  against  the  backdrop  of  the  paper.   Similarly,  each  of  the  features  of  the  London  Underground  map  necessary  for  conveying   information  about  the  best  possible  routes  between  stations  is  perceptually  accessible.  For   example,  individual  railway  lines  of  the  Underground  system  are  syntactically  salient   because  they  are  represented  in  the  map  as  distinctly  coloured  lines  set  against  a   uniformly  white  background.  Had  the  same  colour  but  different  degrees  of  saturation  been   used  for  each  of  the  lines,  the  distinction  between  these  lines  would  have  been  less   syntactically  salient  for  the  average  user  of  the  map,  since  humans  generally  do  not  have   the  same  capacity  to  recognize  differences  between  degrees  of  saturation  that  they  do  to   distinguish  between  different  colours.  Had  identical  colours  and  degrees  of  saturation   been  used,  the  lines  representing  railway  lines  would  be  completely  indistinguishable  for   the  user,  and  thus  not  syntactically  salient  at  all.  The  pieces  of  which  molecular  models  are   built  are  clearly  also  syntactically  salient:  they  are  very  easily  perceived  against  the   backdrop  of  the  three-­‐dimensional  space  in  which  they  are  constructed.   Note  that  whether  or  not  an  aspect  of  a  representation  is  syntactically  salient   depends  on  the  perceptual  capacities  of  the  user(s)  of  that  representation.  If  someone  is   colourblind,  then  a  map  of  the  London  Underground  in  which  the  same  colour  but   different  degrees  of  saturation  were  used  for  each  of  the  railway  lines  might  be  more   Successful  Visual  Epistemic  Representation     19   syntactically  salient  for  him.  However,  we  must  keep  in  mind  that  each  of  our  examples  of   successful  epistemic  representation  is  designed  to  make  the  relevant  features  syntactically   salient  for  most  of  its  intended  users.  Thus,  since  most  people  aren’t  colourblind,  the   different  railway  lines  are  represented  with  different  colours,  which  are  easily   distinguishable  from  one  another  for  the  average  person.   The  syntactic  salience  of  the  parts  of  the  vehicle  that  represent  subcomponents  of   the  phenomenon  of  interest  contributes  to  the  success  of  an  epistemic  representation.  But   it  is  possible  to  represent  these  subcomponents  in  a  variety  of  equally  syntactically  salient   ways,  not  all  of  which  are  equally  able  to  give  the  user  the  kind  of  access  to  the   phenomenon  of  interest  she  seeks  through  using  an  epistemic  representation.  For  example,   consider  an  alternative  representation  of  the  London  Underground  in  which  the  railway   lines  are  depicted  in  parallel  to  one  another,  rather  than  as  a  network,  with  interchange   stations  labelled  with  the  other  line(s)  that  can  be  accessed  at  them  in  parentheses  next  to   their  names.13  So,  for  example,  along  the  Bakerloo  line,  Picadilly  Circus  Station  would  be   labelled  ‘Picadilly  Circus  (Picadilly)’,  since  the  Bakerloo  and  Picadilly  lines  intersect  at   Picadilly  Circus  Station  (Figure  2).                                                                                                                     13  Note  that  this  is  different  from  the  parallel-­‐lines  representation  mentioned  in  Section  3,  in  which   interchange  stations  were  not  labelled.     Successful  Visual  Epistemic  Representation     20     Such  a  representation  of  the  London  Underground  makes  the  same  bits  of   information  about  the  relative  positions  of  stations  along  each  line  and  the  locations  of   interchange  stations  just  as  syntactically  salient  as  the  map  does,  since  they  are  equally   perceptually  available  to  the  user.  Just  as  a  user  has  no  problem  detecting  the  white  circles   on  the  map,  she  also  has  no  problem  detecting  the  names  of  the  other  lines  that  can  be   accessed  at  an  interchange  station:  she  can  easily  see  their  names  in  parentheses  next  to   the  name  of  the  station  in  question.  However,  it  would  be  much  more  difficult  to  use  such  a   representation  for  the  purpose  of  determining  the  optimal  route  between  stations  than  it   is  to  use  the  map.  While  the  individual  pieces  of  information  that  are  necessary  to  identify   possible  routes  –  positions  of  stations  along  each  line  and  locations  of  interchange  stations   –  are  syntactically  salient,  the  possible  routes  themselves,  and  thus  information  about   which  of  these  routes  is  best,  are  more  difficult  to  discern.  In  order  to  find  these  routes,  a   user  must  perform  additional  inferential  steps  to  decode,  so  to  speak,  the  alternative   Successful  Visual  Epistemic  Representation     21   representation.  But  this  kind  of  extra  work  is  precisely  what  a  user  seeks  to  minimize   through  the  use  of  an  epistemic  representation.     Similarly,  consider  some  alternative  ways  of  representing  molecular  structure  that   also  render  its  subcomponents  –  atomic  positions  and  bond  lengths  and  types  –   syntactically  salient.  For  instance,  a  list  of  atomic  coordinates  together  with  a  specification   of  the  lengths  and  types  of  bonds  between  each  pair  of  atoms  makes  all  the  relevant   subcomponents  syntactically  salient;  nevertheless,  the  overall  structure  of  the  molecule   would,  as  with  the  alternative  parallel-­‐lines  representation  of  the  London  Underground,   require  the  user  to  perform  a  number  of  additional  inferential  steps  to  ‘see’  this  structure.   A  two-­‐dimensional  image  of  the  structure  fares  better,  since  it  is  possible  to  discern  three-­‐ dimensional  structure  from  such  an  image  with  fewer  and  simpler  inferences.  But  the   three-­‐dimensional  model  is  best.     4.2  Semantic  salience  of  phenomenon  of  interest   These  alternative  representations  of  the  London  Underground  and  molecular   structure  lack  a  feature  that  Kulvicki  (2010)  calls  semantic  salience.  Semantic  salience   refers  to  the  ease  with  which  syntactically  salient  features  of  the  representation  convey   their  content  to  the  representation’s  user.  In  order  for  a  part  of  a  representation  to  be   semantically  salient,  it  must  be  straightforward  for  a  user  to  determine  what  that  part   represents:  “there  must  be  a  plan  of  correlation  between  features  of  the  representation   and  features  of  the  data  that  is  easy  to  grasp”  (Kulvicki,  2010,  p.  301).  For  example,   suppose  you  want  to  represent  a  temperature  gradient  in  which  the  temperature   decreases  continuously  as  you  move  away  from  a  certain  point.  Representing  the  highest   Successful  Visual  Epistemic  Representation     22   temperature  with  white,  the  lowest  with  black,  and  the  remainder  on  a  grayscale  with   lighter  shades  corresponding  to  higher  temperatures  makes  this  gradient  semantically   salient:  it  is  easy  to  interpret  the  light-­‐to-­‐dark  grayscale  as  corresponding  to  a  high-­‐to-­‐low   temperature  scale.  One  could  also  arbitrarily  assign  shades  of  gray  to  temperatures,  but   the  resultant  image  would  not  be  semantically  salient:  it  would  be  difficult  to  see  that  the   temperature  decreases  continuously  away  from  the  hot  spot,  since  one  would  have  to  refer   back  to  the  key  that  assigns  temperatures  to  colours  repeatedly  before  being  able  to  make   this  determination.   The  extent  to  which  something  is  a  successful  epistemic  representation  is   determined  not  only  by  the  syntactic  salience  of  the  subcomponents  of  the  vehicle   representing  parts  of  the  phenomenon  of  interest,  but  also  whether  the  phenomenon  of   interest  is  semantically  salient.  In  the  case  of  the  London  Underground,  information  about   the  phenomenon  of  interest  –  possible  routes  between  stations  –  is  semantically  salient  in   the  map,  but  not  in  the  parallel-­‐lines  representation.  The  difference  between  these   representations  lies  in  the  ways  in  which  relative  positions  of  the  railway  lines  vis-­‐à-­‐vis   interchange  stations  are  represented.  In  the  map,  it  is  easy  to  see  that  the  intersection  of   lines  with  white  circles  represents  places  where  the  lines  literally  cross,  allowing  users  to   travel  between  them.  That  is,  the  locations  of  interchange  stations  are  semantically  salient   and  this  is  necessary  for  making  possible  routes  between  stations  semantically  salient  as   well.     The  parallel-­‐lines  representation,  on  the  other  hand,  forces  its  user  to  perform   extra  steps  in  her  reasoning  to  obtain  the  same  information;  the  locations  of  the   interchange  stations  –  and  thereby  also  possible  routes  between  stations  –  are  not   Successful  Visual  Epistemic  Representation     23   semantically  salient  in  this  representation.  Labelling  interchange  stations  with  the   name(s)  of  the  intersecting  line(s)  makes  information  about  possible  routes  between   stations  more  difficult  to  grasp  than  in  the  case  of  the  map,  in  which  interchange  stations   are  marked  with  a  white  circle  along  two  or  more  intersecting  or  adjacent  lines.  And  it  is   precisely  this  information  that  is  required  to  determine  possible  routes  between  stations   when  stations  do  not  lie  along  the  same  line.   In  the  molecular  modelling  examples,  the  structures  of  the  molecules  –  the   phenomena  of  interest  –  are  semantically  salient  in  the  physical  models.  It  is   straightforward  to  interpret  the  physical  structure  of  the  model  as  the  structure  of  the   molecule.  This  is  not  so  for  some  alternative  representations  that  also  make  the   subcomponents  of  the  structures  syntactically  salient.  For  instance,  a  list  of  the   coordinates  of  each  atom  together  with  a  list  of  the  types  of  bonds  that  join  them  makes  all   the  relevant  subcomponents  of  the  structure  syntactically  salient,  but  the  overall  structure   of  the  molecule  is  more  difficult  to  determine.  As  with  the  alternative  parallel-­‐lines   representation  of  the  London  Underground,  a  user  would  have  to  perform  a  number  of   additional  inferential  steps  to  ‘see’  this  structure.  A  two-­‐dimensional  image  of  the   structure  fares  slightly  better,  but  since  the  three-­‐dimensional  structure  is  the   phenomenon  of  interest,  the  models  make  this  structure  more  semantically  salient  than   their  two-­‐dimensional  counterparts.   Thus,  we  can  now  see  the  role  that  ‘mirroring’  may  play  in  successful  epistemic   representation:  it  may  contribute  to  the  semantic  salience  of  the  phenomenon  of  interest.   For  instance,  the  London  Underground  map  more  closely  mirrors  the  railway  network   than  the  parallel  lines  representation,  since  the  lines  in  the  network  do,  in  fact,  cross  one   Successful  Visual  Epistemic  Representation     24   another.  Similarly,  while  molecular  structure  could  be  represented  in  a  number  of   different  ways,  not  all  of  them  make  the  structure  as  easy  to  grasp  as  molecular  models  do.   Thus,  even  though  mirroring  relations  are  not,  strictly  speaking,  necessary  for  successful   epistemic  representation,  they  may  play  a  role  nonetheless  in  securing  semantic  salience.     5.  Successful  visual  epistemic  representation   I  have  outlined  two  features  that  contribute  to  successful  visual  epistemic   representation:  that  the  vehicle  of  representation  contain  sufficiently  accurate  information   about  the  phenomenon  of  interest  for  the  user's  purpose,  and  that  it  effectively  convey  this   information  to  the  representation  user.  Both  of  these  features  may  be  present  to  varying   degrees.  Accordingly,  vehicles  of  epistemic  representation  may  be  more  or  less  successful,   depending  on  the  extent  to  which  these  features  are  realized.   This  is  especially  true  because  sometimes  one  feature  of  successful  epistemic   representation  comes  at  the  cost  of  another.  Consider  again  the  map  of  the  London   Underground.  Recall  that  users  of  this  map  are  interested  in  possible  routes  between   stations,  with  the  ultimate  aim  of  determining  which  of  these  is  most  efficient.  Given  this   aim,  one  might  argue  that  this  map  could  be  made  to  better  serve  its  users  if  it  depicted  the   stations  and  railway  lines  to  scale,  thereby  representing  possible  routes  between  stations   more  accurately.  After  all,  this  would  give  users  the  information  they  currently  are  able  to   extract  from  the  standard  map,  as  well  as  other  potentially  relevant  information.  For   example,  it  would  be  possible  to  better  estimate  travel  times  from  such  a  map14  or  to   determine  when  it  might  be  worthwhile  to  walk  between  stations,  rather  than  taking  the                                                                                                                   14  Of  course,  in  order  to  do  this,  one  would  have  to  take  into  consideration  things  like  congestion  at  each   station,  which  would  determine  how  long  trains  stop  there.       Successful  Visual  Epistemic  Representation     25   Underground.  This  additional  information  would  make  the  more  accurate  for  the  purpose   of  determining  the  most  efficient  route  between  stations.   However,  such  an  increase  in  accuracy  would  come  at  the  expense  of  the  syntactic   salience  resulting  from  the  stations  being  positioned  evenly  along  the  lines  and  the  lines   crossing  one  another  only  at  ninety  or  forty-­‐five  degree  angles.  For  in  this  case,  the  areas   of  the  map  corresponding  to  parts  of  the  Underground  in  which  stations  are  close  together   would  be  densely  populated  by  station  marks  and  labels,  making  it  difficult  to  distinguish   between  the  stations.  And  the  ability  to  easily  locate  different  stations  on  the  map  is   essential  for  the  map’s  performing  its  primary  epistemic  function:  to  allow  users  to  most   efficiently  determine  the  best  routes  between  stations.   Tradeoffs  between  the  accuracy  of  the  information  contained  in  the  vehicle  and  the   extent  to  which  that  information  is  conveyed  to  the  user  exist  not  as  a  matter  of  law,  but  as   a  matter  of  fact.  In  principle,  there  is  nothing  precluding  a  vehicle  to  both  contain   information  that  is  maximally  accurate  for  the  user’s  purpose  and  to  effectively  convey   that  information.  In  practice,  however,  it  is  difficult  to  fully  realize  both  of  these  features  at   the  same  time,  except  perhaps  in  the  simplest  cases.  The  crucial  point  is  that  the  success  of   visual  epistemic  representation  depends  on  both  features  and,  accordingly,  how  well  they   are  balanced  with  respect  to  the  representation  user  and  the  purpose  for  which  she  wishes   to  gain  information  about  the  phenomenon  of  interest.       6.  Conclusion     I  have  argued  that  the  success  of  a  visual  epistemic  representation  depends  on  the   extent  to  which  it  contains  sufficiently  accurate  information  about  the  phenomenon  of   Successful  Visual  Epistemic  Representation     26   interest  for  the  user’s  purpose  and  makes  this  information  readily  accessible  to  her.  In  so   doing,  I  have  introduced  some  ways  in  which  we  may  compare  representations  to  one   another,  determining  the  degree  to  which  they  are  successful  in  a  particular  context,   defined  in  terms  of  a  user’s  background,  training,  cognitive  capacity  and  interests.  Thus,   this  paper  develops  accounts  focused  on  the  user-­‐  and  purpose-­‐specificity  of   representation  (mentioned  in  the  beginning  of  Section  2)  by  specifying  how  the  user  and   purpose  affect  the  choice  of  representational  vehicle  as  a  tool  for  gaining  information.  The   purpose  determines  how  accurate  the  information  contained  in  the  vehicle  of   representation  need  be,  while  the  background  and  cognitive  capacity  of  the  representation   user  determines  what  is  required  for  that  information  to  be  effectively  conveyed  to  her.       Rather  than  giving  a  set  of  necessary  and/or  sufficient  conditions  for  epistemic   representation,  this  account  instead  identifies  features  that  contribute  to  its  successful  use   as  a  tool  for  gaining  information.  It  thus  both  departs  from  the  standard  methodology  of   analyzing  what  is  required  for  a  scientific  model  to  be  a  representation  of  its  target  system   at  all.  An  approach  that  acknowledges  that  actual  representations  vary  with  respect  to  the   extent  to  which  they  give  their  users  epistemic  access  to  a  phenomenon  of  interest   promises  to  more  accurately  reflect  scientific  practice,  where  a  variety  of  representational   vehicles  are  used  for  myriad  purposes.     The  account  developed  in  this  paper  focuses  on  visual  representation.  A  question   for  future  work  is  whether  it  might  be  fruitfully  extended  to  other  modes  of  epistemic   representation,  such  as  mathematical  models,  and  if  so,  how?  Like  visual  representations,   the  success  of  mathematical  models  also  depends  in  part  on  their  containing  information   that  is  sufficiently  accurate  for  the  user's  purpose.  The  notions  of  semantic  and  syntactic   Successful  Visual  Epistemic  Representation     27   salience,  however,  are  likely  to  have  limited  applicability  to  mathematical  models,  since   visualization  of  their  targets  may  be  impossible  or  misleading.  For  instance,  the  position  of   a  particle  may  be  represented  by  a  probability  distribution,  i.e.  as  a  ‘superposition’  of   different  positions.  Yet  it  is  impossible  to  visualize  what  it  would  mean  for  the  particle  to   be  in  such  a  superposition.  Nevertheless,  mathematical  models  make  the  information  they   contain  readily  available  to  users  who  have  the  requisite  training.  Whether  the  notions  of   semantic  and  syntactic  salience  could  be  fruitfully  brought  to  bear  in  the  realm  of   mathematical  models,  and  if  so,  how  important  they  would  be  for  understanding  these   kinds  of  models  as  tools  for  conveying  information,  are  questions  worthy  of  further   attention.       Acknowledgments   For  comments  on  earlier  drafts  of  this  paper  and  helpful  discussions,  I’d  like  to  thank   Gillian  Barker,  Jossi  Berkovitz,  Anjan  Chakravartty,  Alex  Djedovic,  Eugene  Earnshaw   Whyte,  Roman  Frigg,  Fermín  Fulda,  Cory  Lewis,  Greg  Lusk,  Margaret  Morrison,  Isaac   Record,  Mauricio  Suárez,  Jim  Weatherall,  and  Rasmus  Grønfeldt  Winther.  I’m  grateful  also   to  audiences  at  the  Models  and 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