2. Immanuel Kant’s Epistemology Life – Born in Königsberg, Prussia (now part of Russia) in 1724. – His family was originally from Scotland. (The original family name was ‘Cant.’) – The family immigrated to Prussia to avoid religious persecution. – Never traveled more than 60 miles from Königsberg, and didn’t leave it at all during a forty year stretch.

3. – Attended the University of Königsberg from 1740 – 1755. – In 1755, received his doctorate and became a Lecturer at the University. He was named full professor in 1770. – Author of three of the greatest works in the history of philosophy. The Critique of Pure Reason (1781) – on Epistemology The Critique of Practical Reason (1788) – on Ethics

4. The Critique of Judgment (1790) – on Aesthetics – A man of precise habits. Would stroll every day, for exactly one hour, eight times up and down the same street. The street came to be called “The Philosopher’s Walk.” So punctual, that the housewives of Königsberg set their clocks by the time he took his walk.

5. – Died, very sadly, totally senile, at Königsberg in 1804. Response to Hume – Given his temperament, Kant was not the sort of man who could abide Hume’s suggestion that humans are emotional, not rational, beings. – Nor could Kant abide Hume’s claim that, at best, science and philosophy are games people play to have fun, rather than ways of attaining truth.

6. – Still, in a sense, Kant gave Hume the credit for all he accomplished: “I openly confess my recollection of David Hume was the very thing which many years ago first interrupted my dogmatic slumber and gave my investigations in the field of speculative philosophy a quite new direction.” Immanuel Kant, Prolegomena to any Future Metaphysics (1783)

7. – Hume had reasoned that, since it is neither a Relation of Ideas nor a Matter of Fact, the Principle of Universal Causation (PUC) is, philosophically speaking, bogus. – Kant conceded that PUC is neither a Relation of Ideas nor a Matter of Fact. – Kant insisted, however, that this does NOT mean that PUC is philosophically bogus.

8. Kant’s Analysis of Perception – Every perception is a two-fold reality: i.) raw sense data and ii.) the organizing and structuring of that data by the mind. – Sense data, in and of itself, is a meaningless jumble. – Sense data makes sense only after it has been organized and structured by the mind’s categories.

9. –Category: A built in, “hard-wired” capacity of the human mind by which it organizes and structures raw sense data. One of the categories is PUC. – One may see a similarity between Kant’s view of perception and Aristotle’s view of substance. – For Aristotle, a substance is created when a form organizes and structures inherently formless and structureless prime matter.

10. – For Kant, a perception is created when the mind’s categories organize and structure raw and meaningless sense data. – An Analogy: Suppose you had a massive heap of coins of different types that were all mixed up. While they remain in the heap, all mixed up, the coins really have no value.

11. You cannot go to the store and buy something with a massive, mixed up heap of coins. Before you can spend the coins, you have to sort them with a coin sorter. The coins don’t really have any true value until they are sorted by the coin sorter. In this analogy, raw sense data is like the massive, mixed up heap of coins. In itself, raw sense data is meaningless jumble.

12. The coin sorter is analogous to the mind’s categories. The coin sorter provides organization and structure and, thereby, value to the massive, mixed up heap of coins. The mind’s categories provide organization and structure and, thereby, meaning to jumbled up, raw sense data.

13. How does Kant’s analysis of perception show that PUC is not philosophically bogus? – “[PUC] is neither a generalization from experience [a Matter of Fact] nor an analytic truth [a Relation of Ideas], but, rather, a rule for ‘setting up’ our world.... Like a rule in chess, [PUC] is not a move within the game but one of the rules that defines the game.... So too, for our belief in the ‘external’ or material world....

14. – “Our experience alone will not tell us whether we are dreaming or not, and the idea of the material (‘external’) world is not a [Relation of Ideas].... [The material world] too is one of the rules that we use to constitute our experience, namely, that we shall always interpret our experience of [sensible] objects [as being] in space, external to us, and material.” Robert C. Solomon, Introducing Philosophy, p. 215

15. – PUC and the other categories are, as it were, the “laws of experience.” – They are not true; rather, they make empirical truth claims possible. – Asking why the mind organizes raw sense data by PUC, or by any of the other categories, is exactly as silly as asking why a criminal is put in jail. – The answer, in both cases, is the same: “That’s the law.”

16. Kant’s Two Worlds – A consequence of Kant’s analysis of perception is that there are really two worlds: The Noumenal World and the Phenomenal World. – Noumenal World The world of “things in themselves.” This the the world from which raw sense data originates. Human beings do not live in this world and have no knowledge of it.

17. – The Phenomenal World The world of perception. The world of sense data after it has been organized and structured by the mind’s categories. This is the world in which humans live and of which they have knowledge.

18. – “[W]e indeed, rightly considering objects of sense as mere appearances, confess, thereby, that [the appearances] are based upon a thing in itself, though we know not this thing as it is in itself, but only know its appearances, namely, the way in which our senses are affected by this unknown something.” Immanuel Kant, Prolegomena to Any Future Metaphysics

19. Kant’s “Copernican Revolution” in Epistemology – Humans can have no knowledge of “things in themselves.” – Order and structure, at least the order and structure of humans, do not exist “out there” in the noumenal world. – (For all humans know, the noumenal world might as well be Heraclitus’ formless flux.) – Order and structure, at least those of humans, exist “in here,” i.e. in the phenomenal world of the human mind.

20. Two Very Important Questions: – Can we be sure that each human mind organizes and structures the raw sense data of the noumenal world in the same way, by means of the same categories? – Since the noumenal world might as well be Heraclitus’ formless flux, isn’t it possible that, à la the ancient Protagorian relativists, each human being projects a different order and structure on the noumenal world, thereby creating his/her own individual and unique phenomenal world?

21. – By means of what he called a “Transcendental Deduction,” Kant attempted to argue, in The Critique of Pure Reason, that the answers to these questions are respectively “Yes” and “No.” – To challenge Kant, an episode of Star Trek: The Next Generation

22. The consensus among philosophers is that Kant’s “Transcendental Deduction” failed. At this point, therefore, we must concede that the Protagorians could have been right all those thousands of years ago. It’s possible that each human being lives in his/her own world, a world of his/her own making.