Immanuel Kant (1724-1804)

Rescuing the Scientific Method by Affirming the Primacy of our Subjectivity
Rescuing Free Will in a World Determined by Cause and Effect

Kant was another great synthesizer in the history of philosophy who melds the rationalism of Descartes with the empiricism of Locke

  • rationalists: the basis for human knowledge is in the mind
  • empiricists: all knowledge of the world proceeds from the senses

Kant believed that both sensation and reason contribute to our conception of the world:

All knowledge comes from sensation, but those sensations are filtered and altered by the conditions of the mind. Furthermore, it is the attributes of reason which create the human conception of reality. (Compare to seeing the world through a pair of red sun glasses. Or compare to the shape water takes when it is poured into a pitcher.)

So, Time and Space become physical entities through human modes of perception. The law of causality belongs to the human mind. Our innate perception of the world demands cause and effect. This mode of perception shapes our understanding of the material substance of reality.  (In this way Kant rebuts Hume's radical empiricism: his belief that cause and effect cannot be proven as a law.) 

(Compare to the different responses a cat and a human would have to a ball rolled by them. The cat would chase the ball; the human would look to see who had rolled the ball.)

However, Kant also believed that the apparatus of reason prevents us from knowing the world in itself; we can only know how the world appears to us.

the thing in itself: the substance of the material world

the thing for me: how the material world appears to me die to the forms of knowledge

Kant argued that it was impossible to prove the existence of God either through reason (Descartes) or experience (Aristotle). However, he insisted that the existence of a soul, of God, and of human free will was a moral necessity. Therefore, for these practical reasons we must possess an innate ability to distinguish right from wrong in the same way that we perceive phenomena as linked in a causal sequence. For Kant moral sense precedes experience-- it applies to all people at all times.

Kant also believed that only through moral action do we act freely. The conditions of the environment and the specificity of the apparatus (physical and mental) with which we are born determine our behavior. Only by engaging in difficult moral decisions can we achieve freedom and actually participate in the world as it is beyond our sensory perception.

The Categorical Imperative: "Act as if the maxim of your action were to become a Universal Law of Nature."

"Treat others not only as a means but as an end."