By focusing on the nature and function of suppositions, particularly absolute presuppositions, we can clarify a number of obscurities in Kant’s Critique of Pure Reason (particularly obscurities relating to the ‘principles’ a/k/a synthetic a priori judgments), better appreciate the Critique, and improve our own thinking. Obscurities clarified include the following: • How, precisely, are the sensory-perception and conceptual aspects of our thinking related? • What exactly are the principles? How do they function? • How can our use of the principles (...) be justified? • What is the limit (proper scope) of our justified use of the principles? • Do we need to show that appearances necessarily conform to the principles? • Do we ‘know’ the principles? • How do we acquire the principles? • Are the principles permanent, or do they change? • Why do the principles change? (shrink)