REALISM AND EXTERNAL WORLD OBJECTS

1
REALISM AND EXTERNAL WORLD OBJECTS

• Stace (1886-1967) defines realism as the view
  that some entities sometimes exist without being
  experienced by any mind.
• realismdf. To be real is to exist apart from
  perception. Gould
• Both of these assertions about realism concern
  objects in the external world. A realist
  believes, with common sense, that ordinary
  objects like tables dont go out of existence
  when no one is looking at them, touching them and
  so forth.

2
EXISTENCE AND KNOWLEDGE

• Realists believe that objects exist when no one
  is aware of them. This is because realism asserts
  that knowledge or awareness makes no difference
  to the object - the object might exist without
  being known or whether anyone is conscious of it
  or not.
• For realism, there is no necessary relation
  between the existence of an external world object
  and mind. (This is something that Berkeley will
  assert is necessary.) Accordingly, realism
  asserts that objects could possibly exist apart
  from minds.
• But Stace says realists assert more than that
  objects might exist apart from minds. Rather,
  they assert that they do exist apart from minds.

3
EXISTENCE, PERCEPTION, BELIEF, AND PROOF

• Stace To refute the proposition that objects
  continue to exist apart from perception is to
  refute realism.
• However, Stace says that he cant prove that
  realism is false, that it is false that objects
  exist when not being perceived. Instead, all he
  can prove, or will attempt to prove is that we
  dont have the slightest reason to believe that
  objects continue to exist when not being
  perceived.
• And Stace will say that, since we have no
  evidence or reason to believe that things exist
  when we are not perceiving them, we ought not to
  believe that they do exist when not being
  perceived.

4
BURDEN OF PROOF

• Stace says that, strictly speaking, he cannot
  prove that realism is false. However, he says
  that the realist cannot prove that it is true.
  And Stace thinks that the burden of proof is on
  the realist that objects exist unperceived. This
  is because there is no evidence that they do, and
  there is no reason to believe that they do.
• For Stace, believing in the existence of
  unperceived objects is like believing in a
  unicorn on Mars. He cant prove that there is no
  unicorn on Mars, but since there is not the
  slightest evidence or reason to believe that
  there is one, we shouldnt believe that there is
  one. (This is like my invisible rhinoceros.)

5
EXTERNAL WORLD OBJECTS AS PHYSICAL

• Stace It makes no difference to the refutation
  of realism whether or not external world objects,
  like tables and chairs, are physical objects as
  common sense and science both suppose. He says
  he will assume that they are physical.
• However, even as physical we cannot know that
  they exist unperceived. And because we cannot
  know that they do, there is no reason to assert
  that physical objects do exist when no mind is
  perceiving them.

6
OBJECTS AND KNOWLEDGE

• For Stace, objects can only be known or proved to
  exist when they are objects of perception and not
  otherwise.
• Thinking that physical objects exist apart from
  perception is unwarranted, and ought not to be
  believed.
• Stace Realism can be refuted if it can be shown
  that we do not know that any single entity
  exists unexperienced.

7
HOW COULD WE KNOW THAT OBJECTS EXIST UNPERCEIVED?

• Even if objects do exist as a matter of fact,
  Stace wants to know how we could possibly know
  that they do. How can a philosopher prove that
  we know that objects exist unperceived?
• Stace There is no possible way in which we
  could know this, we do not know this, and so we
  have no reason to believe it.
• Where could a realist have gotten the knowledge
  that his desk existed in his study when he was
  away for the day? And if he says that he knows
  that it did, how could that knowledge be
  justified?

8
SENSE PERCEPTION AND INFERENCE I

• There are only two ways in which it could be
  asserted that the existence of an external world
  object of perception ( a sense-object) such as
  a desk can be established.
• 1. By perception.
• 2. By inference based upon perception.
• For instance, I think that objects in this room
  now exist because I see them. That is knowledge
  of objects through perception. On the other
  hand, I can infer that a person in the hallway
  exists because I hear footsteps. The object of
  perception is the footsteps. And I can infer
  from the auditory perception of these things that
  a person exists in the hallway.

9
SENSE PERCEPTION AND INFERENCE II

• Knowledge of objects in perception is stronger
  epistemologically than inference, since it is
  always possible that the inference is incorrect.
  For instance, maybe a tape recorder has been left
  in the hall which plays sounds of footsteps when
  no one is really there.
• Of course, even direct perception is not
  conclusive evidence that external world objects
  exist. This is because of the kind of skeptical
  arguments which we have already seen. Stace does
  not pursue this, since his aim is not to try to
  prove what we do know, but what we dont know -
  namely, that objects exist apart from perception.

10
SENSE PERCEPTION AND KNOWLEDGE OF UNPERCEIVED
OBJECTS

• We cannot confirm that an object exists apart
  from perception in perception, since this would
  be to say that we are both perceiving and not
  perceiving the same object at the same time.
• That is, if I want to know if my desk exists
  apart from my perceiving it, I cant use
  perception to see that it exists unperceived,
  since if I am perceiving it, then I am not also
  not perceiving it. And if I am not perceiving
  it, then I am not also perceiving it.
• (Both of the two previous assertions involve a
  law of logic. What is it?)

11
DEDUCTION

• Induction and deduction are both kinds of
  inference, or kinds of reasoning from premises to
  conclusions.
• If the premises of a deductive argument are true,
  then its conclusion follows necessarily from its
  premises. Or, the premises cannot be true while
  the conclusion is false. An example is All
  people are mortal, Socrates is a person,
  therefore Socrates is mortal. It cannot be true
  that all people die, and that Socrates is a
  person without its being the case that Socrates
  will die.

12
INDUCTION

• There is no such necessary relation between
  premises and conclusion in an inductive argument.
  That the conclusion follows from the premises is
  probable only, not certain. I reason inductively
  when I say Most of the people who I have met to
  this point at IPFW have been interesting people.
  Therefore I expect that the next person I meet on
  campus will probably be similarly interesting.

13
INDUCTIVE INFERENCE AND KNOWLEDGE OF UNPERCEIVED
OBJECTS I

• Stace Inductive reasoning proceeds always upon
  the basis that what has been found in certain
  observed cases to be true will also be true in
  unobserved cases. For instance, if every stop
  sign that I have seen has been red, I reason
  inductively that stop signs that I have not seen
  are also red.
• However, I cannot observe that an object, like
  the desk in my study, exists when I am not there
  to observe it. Since inductive reasoning depends
  on observed instances to formulate a conclusion,
  and I cant observe something which I am not
  observing, there is no way for me to formulate an
  inductive generalization about the existence of
  unobserved entities.

14
INDUCTIVE INFERENCE AND KNOWLEDGE OF UNPERCEIVED
OBJECTS II

• In inductive reasoning we expect the future to
  resemble the past. For example, we reason
  inductively about a particular object like the
  sun when we expect it to come up tomorrow. And
  we reason inductively about a kind of object like
  apples when we expect future apples to taste like
  past apples.
• However, this reasoning is probable only, not
  certain, based on our past experience. Perhaps
  the sun will not come up tomorrow, and perhaps
  the next apple I eat will taste like a bowl of
  chili. Each of these is logically possible, that
  is, is not intrinsically contradictory.

15
INDUCTIVE INFERENCE AND KNOWLEDGE OF UNPERCEIVED
OBJECTS III

• I cannot reason inductively from the fact that I
  see my desk each time that I enter my study that
  it exists when I am not in my study to see it.
  These are different particular facts, and Stace
  wants to know how could I reason from the fact of
  the first kind to the fact of the second kind?
• Here is what I can say Each time I have entered
  my study I have seen my desk. Therefore, the
  next time that I go into my study I will probably
  see my desk.
• Here is what I cannot say Each time I have
  entered my study I have seen my desk. Therefore,
  my desk exists when I am not perceiving it.

16
DEDUCTIVE INFERENCE AND KNOWLEDGE OF UNPERCEIVED
OBJECTS I

• Deductive inference is formal inference, and
  Stace notes that deductive inference depends on
  the principle of consistency. From PeQ (if P
  then Q) all that we can deduce is that P and Q
  (not-Q) are inconsistent or that P cant be true
  and Q false or that we cant hold P and Q
  together, although either can be held separately.
• If P cannot be true while Q is false, then there
  is a necessary or analytic relation between P and
  Q.

17
DEDUCTIVE INFERENCE AND KNOWLEDGE OF UNPERCEIVED
OBJECTS II

• For instance, let Px is a triangle, and let Qx
  has three sides. Then our deductive inference
  is if x is a triangle, then x has three sides
  (PeQ). P cannot be true and Q false, since then
  our inference would read if x is a triangle,
  then it is false that x has three sides (PeQ).
• Now let Pmy desk exists when I am looking at it,
  and let Qmy desk exists when I am not looking at
  it. Now, PeQ reads like this if it is true
  that my desk exists when I am looking at it, then
  it is false that it exists when I am not looking
  at it. But this is not internally inconsistent,
  and it simply means that it is logically possible
  that my desk exists when I am perceiving it, but
  does not exist when I am not perceiving it.

18
DEDUCTIVE INFERENCE AND KNOWLEDGE OF UNPERCEIVED
OBJECTS III

• Thus, whereas there is a necessary or analytic
  relation between triangularity and
  three-sidedness, there is no similar necessary or
  analytic relation between some things existing
  when it is perceived, and that same things
  existing when it is not being perceived.
• There is nothing contradictory in maintaining
  that no external world object exists when not
  being perceived that does exist when it is being
  perceived.
• And so we cant use deduction to establish the
  existence of unperceived objects.

19
CONCLUSIONS ABOUT INFERRING THE EXISTENCE OF
EXTERNAL WORLD OBJECTS APART FROM PERCEPTION
BASED ON PERCEPTION

• Stace No valid inference from an experienced to
  an unexperienced existence is possible.
• Stace quotes Russell, a realist, here in defense
  of this position Belief in the existence of
  things outside of my own biography must, from the
  standpoint of theoretical logic, be regarded as a
  prejudice, not as a well-grounded theory.
• Therefore Stace says that the burden of proving
  that we know that objects exist apart from
  perception is on the realist who asserts it, and
  not on the philosopher who wants to know how it
  is possible to know that they do.

20
LOVEJOYS CAUSAL ARGUMENT

• A. O. Lovejoy attempted to prove that objects
  exist unperceived by arguing that causal
  relations which hold between objects which are
  being perceived continue to hold when they are
  not being perceived.
• For Lovejoy, if causal laws continue to operate
  when we are not aware of them, then the objects
  which such causal operations concern must also
  exist when we are not perceiving them.

21
AN EXAMPLE OF LOVEJOYS CAUSAL ARGUMENT

• For example, a causal law of combustion holds
  when we watch fire burn logs and turn them to
  ashes. Suppose then that we light a fire, leave
  the room for a couple of hours, and come back and
  find ashes. Lovejoy says that we have a right to
  infer that the causal law of combustion relevant
  here - that fire turns logs to ashes - which
  operates when we watch fires burn, continues to
  operate in our absence.

22
STACES RESPONSE TO LOVEJOYS CAUSAL ARGUMENT I

• For Lovejoy, because we left burning logs and
  returned to find ashes, we can infer that the
  fire continued to exist when not being perceived,
  and we can assume that causality continued to
  operate as normal. He takes this to prove the
  existence of unperceived objects.
• Stace correctly notes that this is a petitio
  principii - begging the question. What
  Lovejoys argument is attempting to prove is that
  the fire burns in our absence, but this is
  precisely what the argument assumes.
• Stace wants to know how can we know that
  causality continues to operate apart from
  perception as it does in perception? Arent we
  simply assuming that it does?

23
STACES RESPONSE TO LOVEJOYS CAUSAL ARGUMENT II

• Stace points out that unexperienced processes -
  like the burning of logs - and unexperienced laws
  - like a law of combustion - are in the same
  position epistemologically as unexperienced
  objects like desks.
• We cant prove that causal laws continue to
  operate in the way in which they have operated
  when we have observed objects which they concern.
  We cant infer that a law of causality continues
  to operate apart from minds simply because we
  have evidence for that law operating when we are
  perceiving objects.

24
STACES RESPONSE TO LOVEJOYS CAUSAL ARGUMENT III

• It is logically possible - not inconsistent -
  that you left the room with a burning fire and
  came back to find ashes, and that nothing
  continued to exist in your absence.
• Leaving a burning fire and returning to find
  ashes is consistent with nothing at all existing
  in the time that you are gone. This is as
  possible as that logs continued to burn in your
  absence. You are simply assuming that the latter
  is the case, not the former. But Stace says that
  you have no philosophical right to make that
  assumption.

25
CAUSALITY, PERCEPTION, AND DEDUCTION

• You cannot perceive that the logs continued to
  burn in your absence since, as absent, you were
  not there to perceive it.
• You cannot infer deductively that, because fire
  consumes logs in your presence (P), therefore
  fire consumes logs in your absence (Q). This is
  because P and Q, is not inconsistent, or there
  is no logical reason why causality which operates
  in perception must operate apart from perception.
  The burden of proof is on the realist who
  maintains that things continue to exist
  unperceived, and that causality continues to
  operate in cases where it is not observed to
  operate.

26
CAUSALITY AND INDUCTION

• You cannot infer inductively that logs continued
  to burn in your absence since you are trying to
  connect different kinds of thing. You can reason
  inductively like this each time that I have
  built a fire and watched it burn, the fire
  consumes the logs and turns them to ashes.
  Therefore, the next time that I light a fire, it
  will probably convert the logs to ashes. But you
  cannot reason like this each time that I have
  built a fire and watched it burn, the fire
  consumes the logs and turns them to ashes.
  Therefore, the fire continues to burn in my
  absence.

27
MOORE AND THE ACT-OBJECT DISTINCTION I

• We have seen that we need to make a distinction
  between the act or event of perception and the
  object of perception - your seeing of this slide
  is one thing and the slide seen is another.
• G. E. Moore (1873-1958) says that a sense datum
  like green is distinct from the awareness of
  green. He reasons like this a green sense datum
  is different from a blue sense datum, and yet
  each has awareness in common. Our awareness
  (sensation) of green is not blue, and our
  awareness of blue is not green. Since each sense
  datum is different, and each has visual sensation
  in common, then we have to make a distinction
  between the act of awareness and the object of
  awareness.

28
MOORE AND THE ACT-OBJECT DISTINCTION II

• If a sense datum is distinct from the sensation
  of it, then the sense datum could exist apart
  from the sensation of it - e.g. if green is
  distinct from the awareness of green, then green
  could exist independently of any awareness of it.
• Stace Possibly this argument of Moores
  proves that green is not mental. I do not know
  whether it proves this or not, but the point is
  unimportant, since I have already admitted that
  sense data like patches of green are not
  mental. He has also admitted that objects like
  desks and logs are physical, not mental.

29
STACE ON MOORE

• Stace Whatever Moores argument proves, it
  certainly does not prove that unexperienced
  entities exist.
• Even if green is physical, independent of mind,
  or exists when being perceived, it does not
  follow that it is physical, independent of mind,
  or continues to exist when it is not being
  perceived.
• Perhaps an object begins to exist when an act of
  perceiving it begins, continues to exist for the
  duration of the act of perception, and ceases to
  exist when the act of perceiving it ceases. This
  is logically possible, and, Stace says, this is
  exactly what we find in experience.

30
THE EXISTENCE OF OBJECTS AND OTHER MINDS I

• What is Staces position about the existence of
  external world objects in relation to other
  minds? He does not directly say, but seems to
  imply that he will accept the testimony of others
  that an object exists when he, Stace, is not
  aware of it. That is, Stace seems to accept that
  a table exists which he is not perceiving it, as
  long as someone else is perceiving it.
• Note the following language in relation to the
  existence of a piece of paper which he, Stace, is
  not perceiving I am at this moment experiencing
  it, and at this moment it exists, he knows that
  because he is perceiving it but how can I know
  that it existed last night in my desk when, so
  far as I know, no mind some mind other than his
  own was experiencing it? How can I know that it
  will continue to exist tonight when there is no
  one in the room? Stace or anyone else.

31
THE EXISTENCE OF OBJECTS AND OTHER MINDS II

• The language of the preceding quote seems to
  suggest that Stace is willing to accept the
  testimony of others that objects exist of which
  he, or any particular person, is not aware.
  Thus, although you are here on campus, and so not
  perceiving any of your furniture at home, you
  could accept that those items of furniture exist
  of which someone other than you is aware.
• This would mean that a sufficient condition of
  any objects existing is that at least one person
  is aware of it in perception. If that is the
  case, then it is not a necessary condition that I
  am aware of it for it to exist.

32
THE EXISTENCE OF OBJECTS AND OTHER MINDS III

• A more thoroughgoing skeptic might challenge
  Stace here, and suggest that the existence of
  other minds are in the same position, relative to
  his own mind, as is the existence of tables and
  chairs apart from awareness. That is, we can
  only perceive directly the body of another
  person, not her mind. Why then should we accept
  the testimony of another person if we have no way
  to confirm that she can perceive things at all?
• On the other hand, if a person were not to accept
  the testimony of others, then the existence of
  all objects in the external world would be tied
  to his perception of them, and he would be locked
  epistemologically in the egocentric predicament -
  external world objects would be strictly relative
  to his perception of them, and he would not be
  able to argue beyond the sphere of his own
  experience.

33
SUMMARY OF STACES VIEW

• Stace maintains that we only have evidence that
  external world objects exist when we are
  perceiving them, and that we cannot reason that
  they exist apart from perception by using
  deductive, inductive, or causal arguments.
• Because we have no evidence that objects exist
  apart from perception, and no argument can be
  provided that they exist unperceived, we ought
  not to believe that they exist apart from
  perception. Instead, we should believe that
  their existence is strictly correlated with our
  acts of perceiving them, such that, when our
  event of perceiving an object begins, so that
  object begins to exist, and when our perceiving
  it ends, so the object ceases to exist.
• This thesis is supported by experience and that
  is what we ought to believe.

34
DIAGRAM OF STACES POSITION

• Object x at t1 Object x at t2
• 8 8
• Act a at t1 Act b at t2
  
• Object x is an external world object like a desk.
  Both act a and act b are acts of perceiving it,
  such as seeing it or touching it. Time t2 is
  some time later than t1, and the interval between
  t1 and t2 could be a second, a minute, an hour,
  or whatever. For Stace there is no reason to
  suppose that x exists at any time between t1 and
  t2..Instead, we should expect that x comes into
  existence at t1 when a begins and ceases to exist
  when a ceases to exist. It then comes into
  existence again at t2 when b begins, and ends
  whenever b ends. Thus, the existence of objects
  is strictly correlated with (8) their perception.

35
STACE AND THE VIDEO CAMERA I

• Recall Staces objection to Lovejoy, that he is
  simply assuming that causality continues to
  operate apart from perception as it does in
  perception. Stace says that we can no more know
  that causal laws continue to hold apart from
  awareness than we can know that the objects which
  the laws are supposed to concern continue to
  exist.
• A variation on Lovejoy Imagine that a video
  camera were set up in front of the fire with a
  blank tape and was set to record the burning of
  the logs. You leave the room with the fire
  burning and return two hours later to find ashes
  where the logs were. You remove the tape from the
  camera, place it in a VCR, and watch a two hour
  tape of a fire burning. At the end of the tape
  the logs have been converted to ashes. Let us
  further assume that there are no ways into or out
  of the room other than a single door, and two
  guards are posted outside of the door during the
  period of recording.

36
STACE AND THE VIDEO CAMERA II

• Does this prove conclusively that the fire
  continued to burn in your absence? If the proof
  is not conclusive, does it nevertheless add
  support to the realists hypothesis? How might
  Stace respond to the suggestion that the camera
  adds support to realism? Notice that the camera
  is being considered as a kind of surrogate
  perceiver, or another kind of non-human mind. Do
  you think that Stace would be willing to see a
  camera as a legitimate source of knowledge of the
  external world? If not, what property or
  properties does a human mind have which a camera
  lacks which makes it credible to tie the
  existence of external world objects to such a
  mind and not to a camera?

37
OBJECTIONS TO STACE I

• Stace Saying that objects exist unperceived is
  like saying that a unicorn exists on Mars. The
  two are alike, he thinks, because there is no
  evidence for either, but is that really the case?
  And are the two really alike?
• It would not seem so. The difference is the way
  in which data relates to each hypothesis. The
  hypothesis that a unicorn exists on Mars, is not
  supported by the data. However, the hypothesis
  that objects continue to exist unperceived is
  supported by the data.

38
OBJECTIONS TO STACE II

• That is, if objects do exist apart from
  perception, then wouldnt I expect to see my desk
  each time that I enter my study? And isnt that
  exactly what I do find? This is what I mean by
  saying that the hypothesis is supported by the
  data.
• On the other hand, if a unicorn did exist on Mars
  we would expect to find data that we do not in
  fact find. Thus the cases are not the same.

39
RUSSELL VS. STACE ON REALISM I

• Recall that Russell says that Belief in the
  existence of things outside of my own biography
  must, from the standpoint of theoretical logic,
  be regarded as a prejudice, not as a
  well-grounded theory. This means that, although
  we believe it to be true, we cannot prove that it
  is true. Why then is Russell a realist?
• Although Russell would admit that it is logically
  possible that objects come into and go out of
  existence with our perceptions of them, that
  there is no reason to suppose that it is true.

40
TWO POSSIBLE THEORIES

• Theory 1 is that objects like desks come into
  existence when we perceive them, and go out of
  existence when we cease to perceive them. Theory
  2 is that objects like desks exist whether we
  perceive them or not.
• Remember that Stace says that we cannot prove
  that objects exist unperceived, and that the
  hypothesis that their existence is paired with
  our perceptions of them is what we find in fact
  in experience. (Theory 1.)
• However, even though the evidence is consistent
  with this hypothesis, it is also consistent with
  the hypothesis that objects which we perceive
  were waiting there to be found by perception.
  This is logically possible too, and is also
  consistent with our experience. (Theory 2.)

41
OCKHAMS RAZOR

• Ockhams razordf. Entities are not to be
  multiplied beyond necessity.
• Ockhams razor means the following things Do not
  use anything in your theory which you do not
  need. Keep it simple. Do not introduce
  complexity to account for whatever it is which
  you are trying to explain unless it is absolutely
  necessary. Less is (usually) more.
• This is a principle of simplicity or economy.
  Applied to theories it says this Of any two
  theories which explain the phenomena equally, the
  simpler of the theories is to be preferred.

42
RUSSELL VS. STACE ON REALISM II

• Russell says that Theory 2 is simpler than Theory
  1, and therefore better.
• Isnt it simpler for objects to continue to exist
  whether anyone is aware of them or not? Why
  should they go into and out of existence strictly
  correlated with events of perception? Doesnt it
  make science simpler to suppose that the
  existence of objects is independent of
  perception?
• Because each theory accounts for the phenomena,
  but Theory 2 is simpler than Theory 1, Theory 2
  is to be preferred to Theory 1.

43
RUSSELL VS. STACE ON REALISM III

• According to Russell, not only does the principal
  of simplicity favor the existence of unperceived
  objects (Theory 2), but Theory 2 leaves
  undiminished our instinctive belief that there
  are objects corresponding to our sense-data.
• For Russell, because Theory 2 leads to no
  philosophical difficulties, is simpler than
  Theory 1, and accords with common sense notions
  which accord with instinctive beliefs, there is
  no reason for rejecting it.
• Further, Russell says that all knowledge must be
  built up upon our instinctive beliefs, and if
  these are rejected, nothing is left. except
  extreme skepticism

44
NAIVE REALISM

• Naive realismdf. Objects retain the properties
  which they have in perception apart from
  perception. For instance, a table which is both
  brown and rectangular in perception is brown and
  rectangular when no one is looking at it.
• Many philosophers maintain that naive realism is
  false, while holding that some version of realism
  is true. For instance, a representative realist
  like Locke will maintain that only some
  properties of an object like a table which are
  known in perception are retained by the object
  apart from perception. Those which are retained
  by the object whether anyone is aware of them or
  not are called primary qualities. Those which
  are not retained by the object when it is not
  being perceived are called secondary qualities.
  (See the handout on this.)
• Other realists, such as Russell, maintain that
  physical objects are vastly different from what
  we are aware of in perception, and do not retain
  either the secondary or the primary qualities
  which they have in perception when they are not
  being perceived. Russell is a scientific
  realist.

45
SCIENTIFIC REALISM I

• Scientific realismdf. There is a
  mind-independent reality which the physical
  sciences, such as physics, investigate. This
  mind-independent reality is the external world.
  As mind-independent, no particular scientist has
  privileged access to the external world. In this
  sense it is a public space equally accessible to
  investigating intellects. The publicity of the
  external world contrasts with the privacy of each
  person's internal world, the world to which
  he/she alone has privileged access.
• Our understanding of the nature of the physical
  world can change in accordance with the
  development of new models for interpreting
  reality. With these models can come a different
  understanding of the fundamental constituents of
  matter. Professor Duchovic "The entities we call
  electrons, protons, neutrons, and quarks are
  simply our BEST MODEL of this external world.
  This model may change in the future when there is
  collective evidence suggesting that the external
  world is not well-represented by the prevailing
  model."

46
SCIENTIFIC REALISM II
A Table as Seen  
  The Atomic Picture of a Section of a Table Á
an atom with a nucleus ()  

Á Á Á Á

Á
Á Á
Á Á

Á Á
Á Á Á
Á
Á Á Á Á


Á
Á Á Á Á

Á Á Á
Á
Although science is realistic, as common sense
is, the mind-independent entities of physics are
very different from ordinary macroscopic objects
like tables and chairs, apples and trees.
Current physical theory tells us that ordinary
macroscopic objects of these kinds are mostly
empty space, consisting of matter too small to be
seen, in rapid motion.
47
SCIENTIFIC REALISM III

• A model of the atom suggests that an atom
  consists of various subatomic particles. The dot
  at the center of the picture to the left
  represents the nucleus of the atom. The nucleus
  of an atom consists of protons and neutrons.
  Both the proton and the neutron are in turn
  composed of three quarks. The circle in the
  diagram represents the parts of the atom which
  are not parts of the nucleus. These are
  electrons. All the objects of the external world
  consist of these entities too small to be seen
  electrons and quarks.

An atom Á
48
SCIENTIFIC REALISM IV

• For scientific realism, Russells table, when
  unperceived, is more like the space of this room,
  in being empty, than it is like the colored,
  substantial object we are aware of in perception.
• In addition, we are not aware of any movement of
  any parts of the table in perception, but there
  is movement going on at the subatomic level.
  Physicist James Trefil says that the nucleus of
  an atom is not static, like the table it helps to
  compose, but is a dynamic place. In this
  place, all kinds of particles are whizzing
  around, bashing into each other, and being
  created and destroyed as their energy is
  converted into mass and their mass is converted
  into energy. Being inside a nucleus is probably
  more like being in the middle of a fireworks
  display on the Fourth of July than anything
  else. (Trefil, James 1001 Things Everyone
  Should Know About Science, pp. 178-179)

49
SCIENTIFIC REALISM V
Light from a Source(s) Strikes the Atoms ( Á )
of the Table
Á
Á
Á
Á
Á
Á
Light travels from the atoms of the table to the
retina of the eye, where it is converted into an
electro-chemical impulse which reaches the visual
cortex of the brain through the optic nerve. The
visual cortex interprets this impulse as a brown,
rectangular object, and the person whose cortex
it is has the experience of seeing the table. The
atoms of the table are neither brown nor
rectangular. Accordingly, properties of the
subject, including properties of her eyes
(electro-chemical impulses) and brain (the
interpretive action of the visual cortex), are
relevant to seeing the table as a complex of
brown and rectangular sense data.
50
SEEING THE PAST I

• Because light travels at a finite rate of speed
  (186,000 miles per second), in seeing an object,
  we are always seeing a past stage of the object.
  If an object were 186,000 miles from us, then we
  would be seeing it as it looked one second ago.
  An object 93,000 miles from us would appear to us
  as it did one-half a second ago, an object 46,500
  miles from us one-quarter a second ago, and so
  forth. Because light travels at such a great
  rate of speed, for an object which is close to
  us, the difference between the image of the
  object in the brain and the object which the
  image is of is so slight as to be virtually
  instantaneous.

51
SEEING THE PAST II

• Because the sun is about 93,000,000 miles from
  earth, we see the sun as it was about 500
  seconds, or about 8 minutes, ago. Accordingly,
  if the sun were to go out of existence, we would
  not know it for 8 minutes. Because of the
  vastness of the universe, and the finite rate of
  speed of light, some of the stars which you see
  in the night sky may no longer exist.
• The time-lag argument in philosophy of perception
  notes what we have seen, that there is always
  some amount of time, however short, between our
  seeing of an object and the object seen.
  Philosophers like Bertrand Russell take this to
  be further evidence that what we are immediately
  aware of in sensation is sense data, not the
  physical objects to which sense data are causally
  related. Because it is possible that an object,
  like a star, may no longer exist which we
  nevertheless see, even perception itself cannot
  be taken as conclusive evidence that the object
  of perception exists.