Still more unequivocal was the sceptical nihilism expressed by Gorgias: - (I) nothing exists; (2) if anything existed, it would be unknowable; (3) if anything existed and were knowable, the knowledge of it could not be communicated.
2 It may be as well to add that the sceptical side of Kantianism is mainly confined to the Critique of Pure Reason, but this side of Kantian thought has been most widely influential.
Though scepticism as a definite school may be said to date only from the time of Pyrrho (q.v.) of Elis, the main currents of Sophistic thought were sceptical in the wider sense of that term.
The prominence given by most of the Sophists to rhetoric, their cultivation of a subjective readiness as the essential equipment for life, their substitution of persuasion for conviction, all mark the sceptical undertone of their teaching.
His first book on the subject was The Sceptical Chemist, published in 1661, in which he criticized the "experiments whereby vulgar Spagyrists are wont to endeavour to evince their Salt, Sulphur and Mercury to be the true Principles of Things."