A trick to using malapropism is to ensure that the two words (the original and the substitute) sound similar enough for the reader to catch onto the intended switch and find humor in the result.
Positivism is a philosophical theory stating that positive knowledge is based on natural phenomena and their properties and relations. Thus, information derived from sensory experience, interpreted through reason and logic, forms the exclusive source of all authoritative knowledge.
Internet Encyclopedia of Philosophy. Search. Pragmatism. Pragmatism is a philosophical movement that includes those who claim that an ideology or proposition is true if it works satisfactorily, that the meaning of a proposition is to be found in the practical consequences of accepting it, and that unpractical ideas are to be rejected.