Sentence:  The best way to demonstrate the possibility of something is to show its actuality, for actuality implies possibility. At least since Kant, <WSD>transcendental</WSD> philosophies have been on the scene. However, such simple demonstration of the possibility of <WSD>transcendental</WSD> philosophy has not been effective and is not likely to be so — so strong is the presumption that <WSD>transcendental</WSD> philosophy just could not be possible, or, if it "was" possible earlier, it is not possible "now". 
Meaning of the word marked with <WSD> tags:  Concerned with the "a priori" or intuitive basis of knowledge, independent of experience.