Immanuel kant united empiricism w/ rationalism. How?

Answer 1

He used a lot of lubricant. Ha ha.

Actually, it might be most accurate to say that he united them by arguing that they were both completely wrong. Nobody's senses and thoughts are completely free to do anything - they operate on limits. Thus, neither senses alone nor thoughts alone can ever directly exceed these limits and see the world in itself.

Instead, the two disciplines needed to work together. Rationalists cannot reasonably deny the entire world of the senses - senses are all we have to know anything but our own minds. Thus any rationalist idea which involved anything other than the mind of the creator itself cannot possibly be correct without a bit of empiricism in it.

Likewise, there are things empiricists must know in order to operate empirically. A rational knowledge of their senses' limitations CAN help them step outside those limitations. Knowledge of history, memory, prediction, and theory keep us from the need to constantly repeat experiments to prove over and over that something is still true if it was true ten seconds ago. Morality and free will are intuitively apparent, yet completely outside of the empirical realm.

All of which are good arguments. So good, in fact, that both groups decided to play nice for a while. I love it when there's a happy ending. ( :

Answer 2

To get an answer that question you will have to read Kant's "Critique of Pure Reason" (and almost certainly one of the many commentaries available by professional philosophers) first. Study of this very difficult book, which is core to modern philosophy, is typically a course in itself in Philosophy degrees. It would not do justice to the "Critique of Pure Reason" to summarise the book in the space available in Yahoo answers, so I fear the short answer is "Sign up for a Philosophy degree to find out". To misrepresent Kant very briefly to the best of my limited understanding (as my degree is not on philosophy), the idea is that people have analytic knowledge about what nature and the world must be essentially, which provides a framework within which they can perceive and interpret synthetic (or empirical if you like) knowledge about how the actual world happens to be.