1. Idealism

2. The Atomic Theory of Matter
The atomic theory poses a challenge to theories of substances or objects
Atomic theory: things are composed of atoms; properties of things depend on nature and motion of atoms
Things are not as they appear
Democritus

3. Dignaga (c. 450), Buddhist
“Though atoms serve as causes of the consciousness of the sense-organs, they are not its actual objects like the sense organs; because the consciousness does not represent the image of the atoms. The consciousness does not arise from what is represented in it. Because they do not exist in substance just like the double moon. Thus both the external things are unfit to be the real objects of consciousness.”

4. Actual and Internal Objects
Aristotle: objects cause perceptions, and are represented in them
Causes of perception = objects of perception
Dignaga: No—
causes are the atoms— actual objects [alambana]
objects are appearances— internal objects [artha]

5. Causes and Effects Causes of perception are the atoms
We don’t see atoms, but their effects
What we see doesn’t exist in reality; it is “like the double moon”
How can we distinguish the aspects of the effects (appearances) that do match the causes?

6. Primary Qualities
Descartes: We perceive clearly and distinctly only the mathematical properties of objects: size, shape, motion
Only they reflect the true natures of things
Locke: Primary qualities are inseparable from objects; atoms have them
Primary qualities are those objects possess according to the atomic theory of matter
They produce simple ideas in us that resemble the primary qualities in the objects

7. Secondary Qualities
Secondary qualities are effects of objects on our nervous systems
They produce ideas in us that do NOT resemble them
Secondary qualities depend on primary qualities
Secondary qualities are response-dependent: to have one is just to produce a certain effect in a perceiver

8. Real and Nominal Essence
Aristotle and Aquinas identify:
The essence of x = the properties necessary to x
The quiddity of x = the definition of x in re
The nature of x = what makes x what it is
Locke: nominal essence = quiddity: uses secondary qualities
Real essence = nature: real internal constitution

9. Idealist Critique Dignaga: We know world only through sense organs
So, we know objects only insofar as they become internal objects
They are objects of consciousness, constituted by consciousness
We know objects only as conditioned by consciousness

10. Argument for Idealism
We have reason to believe that something exists only if we can know it
We can know an object only by making it an object of consciousness
Any object of consciousness is conditioned by consciousness
Anything conditioned by consciousness is mind-dependent
So, we have reason to believe that a thing exists only if it is mind-dependent

11. George Berkeley ( )
Idealism best defense of common sense against scepticism
Descartes’s and Locke’s ideas of objects make no sense
Attack on primary qualities and on substance

12. Against Primary Qualities
We have no basis for thinking any of our ideas corresponds to some mind-independent reality
We cannot judge resemblance to reality
Perceptions of width, height, etc., vary while objects remain unchanged

13. Esse est Percipi We have access only to what is before the mind
A thing can exist only if it is perceived
Do things go out of existence when we aren’t looking at them? No— because God keeps an eye on them for us

14. Kant’s Copernican Revolution
Rationalists: universality and necessity require synthetic a priori
Hume: source not in the world but in us
Kant: source is within us— but it is reason, not custom or habit

15. Kant’s Categories There are innate concepts— the categories
They are logical forms of judgment
They apply only to experience

16. Knowledge —> Objects
“It has hitherto been assumed that our knowledge must conform to the objects; but all attempts to ascertain anything about these objects a priori, by means of concepts, and thus to extend the range of our knowledge, have been rendered abortive by this assumption. Let us then make the experiment whether we may not be more successful in metaphysics, if we assume that the objects must conform to our knowledge.”

17. Kant & Copernicus
“We here propose to do just what Copernicus did in attempting to explain the celestial movements. When he found that he could make no progress by assuming that all the heavenly bodies revolved round the spectator, he reversed the process, and tried the experiment of assuming that the spectator revolved, while the stars remained at rest. We may make the same experiment with regard to the intuition of objects. If the intuition must conform to the nature of the objects, I do not see how we can know anything of them a priori. If, on the other hand, the object conforms to the nature of our faculty of intuition, I can then easily conceive the possibility of such an a priori knowledge.”

18. Laws of the Understanding
“Before objects, are given to me, that is, a priori, I must presuppose in myself laws of the understanding which are expressed in concepts a priori. To these concepts, then, all the objects of experience must necessarily conform.”

19. Limits of Knowledge
“. . . we only know in things a priori that which we ourselves place in them.”
Laws that govern realm of experience are in us— the laws of the understanding
So, we can know things only as experienced by us— not as they are in themselves

20. Kant’s Rationalism
There are innate ideas: pure concepts of the understanding (the categories)
There are synthetic a priori truths (laws of the understanding)
But they apply only within realm of experience

21. Phenomena Phenomena: appearances, objects as we perceive them
Categories apply to them
A priori principles apply to them
We can know them with universality and necessity

22. Noumena
Noumena: things-in-themselves, unconditioned by our cognitive faculties
Categories don’t apply to them
A priori principles don’t apply to them
We can’t know them at all

23. Descartes/Hume/Kant Descartes Hume Kant Synthetic a priori? Yes No Yes
Knowledge
Beyond exp. Yes No No
of world as Yes No No
it is

24. Plato’s Philosophy of Mind
The Good
Participation
This is a
triangle
Form
Recollection
Perception
Object

25. Kant’s Philosophy of Mind
Construction
This is a
triangle
Concept
Perception
Object

26. Kant’s Philosophy of Mind
Understanding
This is a
triangle
Concept
Appearance
Sensibility
Thing in itself