Kant’s transcendental deduction

Kant proposed

• that a priori knowledge could be independent of the content of experience – in disagreement with the empiricists
• that pure a priori knowledge, without any empirical content, can only lead to limited deductions and conclusions about  possible experiences  - in disagreement with the rationalists.

In order to make sense of experience certain a priori, or transcendental conditions, seated in our minds, must exist; they are not provided by experience in general or indeed by a combination of sets of experiences.  

Ideas like time, space and cause are, according to Kant, pure a priori forms without which human beings would not be able to process the world of experience. Specifically, we would not be able to operate in the rule governed world we find ourselves in unless our minds came pre-equipped with concepts such as cause, time and space. The claim that synthetic a priori knowledge is necessary is known as Kant's transcendental deduction and it is the central argument of his Critique of Pure Reason.

Kant’s transcendental deduction brings the perceiver and subjective experience into accounts of the world. Time is not some disembodied clock that that ticks away irrespective of the observer, as Isaac Newton thought; it is an aspect of how the individual interacts with the world. Kant’s insights into the subjective nature of knowledge chime well with Einstein’s concepts of time and space being relative to the observer.