Kant s Transcendental Idealism Critique of Pure Reason
Immanuel Kant
Copernicus
Kant s Copernican Revolution Rationalists: universality and necessity require synthetic a priori knowledge knowledge of the world independent of experience Hume: source not in the world but in us Kant: source is within us but it is reason, not custom or habit
Kant s Copernican Revolution Do our concepts revolve around objects? (as realists think) Or do the objects revolve around our concepts?
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.
Kant & Copernicus 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.
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.
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.
Transcendental Argument q is a necessary condition for the possibility of p (p would be impossible if it weren t the case that q) p Therefore q
Transcendental Argument A priori concepts and laws of the understanding are necessary conditions for the possibility of experience We have experience. Therefore there are a priori concepts and laws of the understanding.
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
Space and Time Space and time are a priori forms of sensibility We perceive things as being in space and time Perceptible objects exist in space and time is a synthetic a priori truth But are things-in-themselves really in space and time?
Categories Quantity Unity object, thing, one, this, that, the Plurality some, several Totality all, every, each
Categories Quality Reality is, yes, true Negation not, no, false Limitation un-, a-, in-
Categories Relation Inherence and Subsistence is, substance, quality, property, exemplifies, participates in, has, instantiates, for example, for instance, such as Causality and Dependence if... then, cause, effect, because, depends, determines, grounds Community reciprocity, if and only if, and, or, unless, part, whole, with
Categories Modality Possibility/Impossibility possible, can, may, might, could Existence/Non-existence is, exists, will Necessity/Contingency necessary, must, needs to, has to, would
Other Categories? Quantity many, few, most, more, less, finitely many, countably many, ø Quality tense (had been, was, is, will be, will have been), aspect (runs, is running, used to run), before, after, since, until Relation is (identity), same, equals, similar, like, near, far, closer than, between, belongs to, is in, is at Modality may, should, ought; generally, typically, normally; knows that, believes that, sees that, fears that; wants to, expects to, intends to; in order to
Synthetic A Priori Judgments Mathematics (e.g., 7+5=12) The world consists of objects that have properties and stand in relation to one another. Every event has a cause. Everything relates to everything else.
Principles of Pure Understanding Every object stands under the necessary conditions of the synthetic unity of the manifold of intuition in a possible experience. In all change of appearances substance is permanent; its quantum in nature is neither increased nor diminished. All alterations take place in conformity with the law of the connection of cause and effect. All substances, in so far as they can be perceived to coexist in space, are in thoroughgoing reciprocity.
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
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
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
Descartes Hume Kant Synthetic a priori? Yes No Yes Knowledge Beyond exp. Yes No No Knowledge of world as Yes No No it is
Plato s Philosophy of Mind The Good Participation This is a triangle Form Recollection Perception Object
Kant s Philosophy of Mind Construction This is a triangle Concept Perception Object
Kant s Philosophy of Mind Understanding This is a triangle Concept Appearance Sensibility Thing in itself
Aristotle s Philosophy of Mind Understanding This is a triangle Concept Appearance = Sensibility Thing in itself
Descartes s Philosophy of Mind Understanding This is a triangle Concept Sensibility ~ Appearance (Match on primary qualities only) Thing in itself
Idealist s Philosophy of Mind Understanding This is a triangle Concept Appearance Sensibility Thing in itself
Kant s Philosophy of Mind Understanding This is a triangle Concept Appearance Sensibility Thing in itself