PHIL 151 History of Modern Philosophy

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PHIL 151 History of Modern Philosophy

• Dr. Martin Godwyn
• Fall 2008
• WEEK 5 Lockes Empiricist Epistemology

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Simple and Complex ideas

• Locke notes that ideas come in varying degrees of
  complexity. He therefore draws a distinction
  between simple and complex ideas
• Simple idea nothing but one uniform conception
  in the mind, and is not distinguishable into
  different ideas.(2.2.1) For example, the idea of
  blueness.
• Complex idea An idea compounded or constructed
  (ultimately) out of more than one simple idea.
  For example, the idea of a unicorn.

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Simple and complex ideas

• Lockes epistemology, as well as seeing knowledge
  as something constructed from ideas, also adopts
  an atomistic approach to ideas
• All ideas (or concepts) are either simple or
  complex. And all complex ideas are (ultimately)
  reducible by analysis to combinations of simple
  ideas, much as today we might say that molecules
  are reducible to combinations of basic elements.

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Ideas and qualities

• One of the most important distinctions that Locke
  introduces is that between the qualities of an
  objects and our ideas of an object.
• Whatsoever the mind perceives in itself, or is
  the immediate object of perception, thought, or
  understanding, that I call idea and the power to
  produce any idea in our mind, I call quality of
  the subject wherein the power is. Thus a
  snow-ball having the power to produce in us the
  ideas of white, cold, and round, the powers to
  produce those ideas in us, as they are in the
  snow-ball, I call qualities and as they are
  sensation or perceptions in our understandings, I
  call them ideas (2.8.8)

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Ideas and qualities

• Its important to keep firmly in mind that
  qualities are in the objects, but ideas are
  entirely in us.
• Thus, when Locke speaks about, for example, the
  quality of redness in a ripe tomato, he is not
  talking about the colour sensation that you have
  when you look at a ripe tomato in normal lighting
  conditions. The sensation what you see is
  always something occurring in your mind.

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Primary and Secondary Qualities

• Locke then distinguishes qualities of material
  objects into two kinds primary and secondary.
• Primary Qualities Properties that are real and
  an intrinsic part of an object, whatever we do to
  it.
• Secondary Qualities Dispositional powers of an
  object to produce in us sensations via their
  primary qualities, but which are dependent on us
  and hence are not intrinsic to it.

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Primary Qualities

• Where Descartes argued that material bodies must
  have extension, Locke agrees, but identifies a
  number of further essential properties
• The primary qualities of bodies are bulk,
  extension, figure, number, and motion. (He
  sometimes adds texture or solidity.)
• These varying properties causally produce in us
  their corresponding ideas.

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Primary Qualities

• Locke says that primary qualities
• are utterly inseparable from the body of an
  object in what state soever it be such as in
  all the alterations and changes it suffers, ...
  it constantly keeps and such as sense constantly
  finds in every particle of matter which has bulk
  enough to be perceived and the mind finds
  inseparable from every particle of matter.
  (2.8.9)

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Primary Qualities

• Locke is not saying that we cannot change the
  primary qualities of a body clearly, we can
  change such things as the shape or motion of a
  body.
• Lockes point is that having some shape or some
  motion (including being at rest as a limiting
  case), etc., is a necessary and essential feature
  of all bodies. They are intrinsic to any body no
  matter what else we might do it.

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Secondary Qualities

• Locke identifies secondary qualities as nothing
  more than powers or as we might say today
  dispositions that bodies have to produce
  sensations in us. Such powers are caused by a
  bodys primary qualities, but are not intrinsic
  to the object itself.
• Thus ripe tomatoes, for example, have a power,
  under appropriate conditions, to produce in us an
  idea (sensation) of redness. That power is the
  (secondary) quality of redness.

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Contrasting Primary/Secondary

• Thus, the secondary quality of redness in a ripe
  tomato is a property of the ripe tomato, but it
  is not intrinsic to the ripe tomato. Why not?
• The reason is that secondary properties are
  relational properties as dependent on us as they
  are on the object. If humans had very different
  visual systems ripe tomatoes might lack the
  ability to bring about ideas of redness in us,
  and without any change to anything intrinsic to
  the tomato itself.

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Contrasting Primary/Secondary

• But Locke argues this is not so with primary
  qualities. For any primary quality, the object
  retains those qualities no matter what might
  happen to us.
• Thus, the primary quality of the shape of the
  tomato is intrinsic to the object. Yes, we can
  change that shape, but it still has its shape
  (whatever that shape happens to be) whatever
  happens to us.

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Tertiary qualities

• Although, like Locke, we shall focus on primary
  and secondary qualities, Locke does occasionally
  mention tertiary qualities.
• Tertiary qualities are, in essence, much like
  secondary qualities powers that a body has to
  produce a change in something else. The
  difference is that in the case of tertiary
  qualities, the change is not the production of an
  idea in us but some other effect.
• Fire, for example, has the tertiary quality of
  melting wax.

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Primary and secondary properties

• Both primary and secondary qualities produce
  ideas (more specifically, sensations) in us.
• Primary qualities are intrinsic to the object
  they have those qualities objectively and
  independently of us.
• Secondary qualities are not intrinsic to the
  object they are capacities (powers) of an
  object to produce ideas in us that depends as
  much on us (the perceiver) as on the object.

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Intrinsic vs. essential

• In describing primary qualities as intrinsic this
  is to say that they are qualities that are
  possessed independently of other things. IN other
  words, they are not relational qualities.
• This is distinct from saying that some quality is
  essential this means that the object cannot
  cease to have that quality and still be that
  thing.

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Intrinsic vs. essential

• However, note that Locke argues that primary
  qualities are essential to being a material body.
  Thus, having a figure (shape) is essential to
  being a body, but having some particular shape
  might not.
• For instance, a lump of material stuff can still
  be the same stuff even though its shape changes.
  The particular shape that stuff has is a primary
  quality (and, hence, is instrinsic to it), but it
  is not generally essential to it that has that
  shape.

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Some Epistemological Issues

• There are a number of issues (interpretive and
  philosophical) surrounding Lockes discussion of
  primary and (especially) secondary qualities.
• With secondary qualities Locke (2.8.13) seems
  ready to concede that there is no reason to
  suppose that our ideas of secondary qualities in
  any way resemble those powers. Indeed, it is hard
  to see how a sensation can resemble a power or
  disposition as such.

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Some Epistemological Issues

• For example, melting of wax (an effect) is caused
  by the a power in fire. But the melting of the
  wax does not (in any obvious way) resemble this
  power in the fire.
• But why does this not apply also to primary
  qualities? Locke seems to think that our ideas of
  primary qualities resemble those qualities.
  (2.8.15). The best explanation for why an apple
  looks round is that it is round, Locke seems to
  think.

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Some Epistemological Issues

• But argument for this view is not easy to find
  he seems to think it is clear from the fact that
  all corporeal objects must have in them primary
  qualities (yet neednt have secondary qualities).
  But is that reason enough to think that our ideas
  of those qualities resemble the qualities
  themselves?
• As well see Berkeley thinks what goes for
  secondary qualities goes for primary qualities.

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Some Metaphysical Issues

• Clearly, background conditions affect whether an
  idea is produced. In complete darkness, tomatoes
  do not produce ideas of redness in us. But do
  background conditions affect the powers something
  has?
• Does a ripe tomato still have the secondary
  quality of redness in a completely dark cupboard?
  What if all light disappeared from the universe?

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Some Metaphysical Issues

• Compare is a fine crystal wine-glass still
  fragile when it is carefully wrapped? Is a
  crystal of salt still soluble when and where
  there is no water? Etc.
• Why is this a problem for Locke? He speaks of
  secondary qualities as being in the object, but
  is it anymore in the object than in the
  totality of conditions that determine whether
  there exists the power to produce ideas in us?

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Lockes theory of perception

• To summarise Lockes account of perception is
  causal representative realism.
• 1. Causal the only way an external world can
  effect our senses is by causal impulse
  Particles hitting our sensory organs.
• 2. Representative Our ideas represent the world.
  Hence, any knowledge of the world is indirect,
  coming via our ideas. (This sets the stage for
  skeptical challenges.)
• 3. Realism there is an external world of
  objective primary qualities.

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Knowledge of the external world

• Like Descartes, Locke thinks we can know that
  there is an external world, but since he rejects
  any knowledge prior to experience, his reasons
  are very different and are based on sensations.
• Roughly speaking, he holds that whilst knowledge
  of the external world is not absolutely certain,
  it doesnt need to be and there is plenty of
  evidence that it is true.

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Lowering the standard

• Locke concedes that it is logically possible that
  we are mistaken in thinking that there is an
  external world, but insists that the evidence of
  the senses is an assurance that deserves the
  name of knowledge. (4.11.3)
• Thus, Locke lowers the standard of justification
  for what counts as knowledge below the standard
  that Descartes thinks is necessary to avoid
  skepticism.

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Knowledge of the external world

• He goes on...
• If we persuade ourselves that our faculties act
  and inform us right, concerning the existence of
  those objects that affect them, it cannot pass
  for an ill-grounded confidence for I think
  nobody can, in earnest, be so sceptical as to be
  uncertain of the existence of those things that
  he sees and feels. At least, he that can doubt so
  far will never have any controversy with me
  since he can never be sure I say anything that is
  contrary to his opinion. (4.11.3)

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Lockes strategy

• Aside from pointing out the psychological
  difficulty in being skeptical, Locke offers some
  direct grounds to think that there is an external
  world. Each of his grounds appeals to certain
  aspects of the world or of our experience and,
  Locke suggests, each is best explained by appeal
  to the existence of a world external to us.
• In other words, Lockes strategy is to posit an
  external world as what is usually called an
  inference to the best explanation (or abductive
  inference) for aspects of common experience.

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The blind and colours

• 1. Those without the relevant organs, such as
  eyes, cannot produce the ideas or colour, etc.
• Those that want the organs of any sense never
  can have the ideas belonging to that sense
  produced in the mind. ... Therefore we cannot but
  be assured that they come in by the organs of
  that sense, and no other way. (4.11.4)

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Sensation is not in our control

• 2. In contrast with the ideas of imagination, we
  cannot, at least in general, avoid having
  sensation it is beyond our control.
• If I turn my eyes at noon towards the sun, I
  cannot avoid the ideas which the light or sun
  then produces in me. (4.11.5)

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Pain vs. remembered pain

• 3. Some sensations are painful when we experience
  them, but are not when merely remembered in our
  imagination.
• The pain of heat or cold, when the idea of it is
  revived in us, gives us no disturbance which,
  when felt, was very troublesome, and is again,
  when actually repeated (4.11.6)

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Coincident sensory modalities

• 4. Our senses are independent of each other, yet
  they give a consistent picture of the world the
  fire we hear, feel, see and smell all at the same
  time.
• He that sees a fire may, if he doubt that it be
  anything more than a bare fancy, feel it too and
  be convinced by putting his hand in it. (4.11.7)

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Coincident sensory modalities

• To see the idea behind that last of these
  arguments, consider the fact that on any given
  occasion one might see any one of an innumerable
  number of possible sights. The same goes for
  hearing, smell, etc. Why then, do they so often
  indicate the same thing, e.g., that there is a
  fire, if not that there is a fire?
• It is as though we throw between two and five
  dice each with thousands of sides, and yet they
  almost always come up with the same face as each
  other surely this is not a coincidence.

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What is the best explanation?

• Lockes strategy seems to be to imply that the
  above facts about our sensations are best
  explained by the existence of an external world.
• Even if it is logically possible that I am
  dreaming or that a demon is deceiving me, which
  Locke concedes, such skeptical hypotheses are
  clearly far inferior as explanations for our
  experiences than the common-sense explanation
  that there really is an external world causing
  our sensations.

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Conclusion

• In conclusion
• when our senses do actually convey into our
  understandings any idea, we cannot but be
  satisfied that there doth something at that time
  really exist without us, which doth affect our
  senses, and by them give notice of itself to our
  apprehensive faculties, and actually produce that
  idea which we then perceive And we cannot so far
  distrust their testimony as to doubt that such
  collections of simple ideas as we have observed
  by our senses to be united together do really
  exist together. (4.11.9)

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Dodging the issue?

• Is Locke right? Has he answered the skeptic or is
  he merely dodging the skeptical question? Must we
  satisfy Descartes standard for knowledge or does
  Lockes slightly lower standard suffice?
• how vain, I say, it is to expect demonstration
  and certainty in things not capable of it and
  refuse assent to very rational propositions, and
  act contrary to very plain and clear truths,
  because they cannot be made out so evident as to
  surmount every the least (I will not say reason,
  but) pretence of doubting. (4.11.10)

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What is the best explanation?

• What, if anything, might make the common-sense
  explanation a better explanation than the
  dreaming or evil demon hypothesis?
• Is it that the common-sense hypothesis simpler?

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The Veil of Perception

• Perhaps the most significant epistemological
  issue for Locke is that his view that all
  knowledge is constructed out of ideas that
  themselves originate in sensory experiences
  creates what is often called a veil of
  perception.
• It might seem that we cannot come to know
  anything about the external world because we are
  forever cut off from that world by our
  perceptions all we ever encounter (ultimately)
  are sensations, not the world itself.