A Cure Worse than the Disease?

Sapere aude! ‘Have courage to use your own reason!’ – that is the motto of enlightenment. – I. Kant

Immanuel Kant was a philosopher who took Hume’s challenge seriously – indeed, more seriously than Hume himself (Kant, 2004). If science is so critical to our understanding of the universe, he reasoned, it must be possible to place it on a firm epistemic foundation, which requires defusing the problem of induction. And so he set out to do just this, though whether and in what sense he succeeded in this project is still a matter of debate.

Kant accepts the empiricist idea that we have no direct access to information about the “real” world (noumena) beyond our mental representations (phenomena). Since metaphysics is about the ultimate nature of reality, any empiricist making metaphysical claims is in the awkward position of using sensation as a guide to the supposedly extra-sensory causes of sensation. To make matters worse, Kant argues persuasively that our sensation is not a passive faculty on which the world impresses itself, but instead involves active (if subconscious) interpretation (a claim richly confirmed by modern psychology). This makes it impossible to know the nature of the world beyond our experience with any confidence – we are trapped in our own minds, as it were. To use a simple analogy, it’s as if we spend our entire lives locked inside a movie theatre with only the images on the screen as a guide to the outside world. We have no way to tell whether and to what extent the images correspond to what’s outside. And since we also know that our expectations and desires influence what see on the screen, we have strong grounds to be skeptical about any claim concerning the world beyond the theatre.