The Ashtray (Or the Man Who Denied Reality) is a book by Errol Morris in which he criticizes the philosophy of Thomas Kuhn.

The conversation grew increasingly heated as they disagreed regarding some fundamental ideas – specifically regarding James Clerk Maxwell's theory of displacement current, and the concept of incommensurability.

[5][1][2][3] In the book, Morris argues that Kuhn was a relativist and a philosophical idealist, contrasting his interpretation of Kuhn's views with his own epistemology, drawing on Hilary Putnam and Saul Kripke, which he describes as "investigative realism", based on the belief that there is an objective reality whilst rejecting naïve realism.

From discussing Kuhn and Paradigm shift, to interviewing Noam Chomsky, Morris utilizes these varying types of images (what he calls "illustrations"[6]) to supplement the information presented.

In a piece for the Los Angeles Review of Books, Philip Kitcher compared Morris' critique to Samuel Johnson's appeal to the stone regarding George Berkeley's belief in subjective idealism, stating that "Morris has no interest in considering what Kuhn might have had in mind", and rejecting his characterisation of Kuhn as a relativist and an irrealist.