A categorical imperative is a 'should' statement, but it is not based on experience (a priori), and doesn't rely on a particular outcome.
It is a universal moral law that helps us achieve our moral duty. (e.g. do not lie)
It logically precedes (or helps us make sense of) experience. We must use reason to deduce these, as they only work from the autonomous will.
Kant showed that we must presume that time moves forwards, as our mind imposes this on our experiences to make sense of them. (see notes on causality) Without this presumption, we could never demonstrate or prove this through experience.
Similarly, if certain actions were logically inconsistent, they would make no sense as universal laws, such as lying. Therefore, 'do not lie' is a categorical imperative.

	Created by Summer Pearce over 9 years ago

AS - Level (Year 1) Ethics (Kantian Ethics) Slide Set on Kant in Detail, created by Summer Pearce on 02/08/2016.