The first group of selections from Language, Truth, and Logic concerned the analytic and a priori tautologies that constitute the truths of philosophy (and mathematics). These selections point beyond such sentences to others.

•  In the selections from ch. V, Ayer is concerned with the synthetic and a posteriori claims that provide the content of natural sciences and ordinary empirical knowledge. The key thing to think about here is Ayer’s claim (p. 212) that there are no absolutely certain empirical claims (no “ostensive” propositions in his terms). This was something that was debated among logical positivists, and it’s something about which Ayer changed his views somewhat in later work. Think also about the related view that “the ‘facts of experience’ can never compel us to abandon a hypothesis” (p. 213). In the case of scientific hypotheses, this is an idea that is most closely associated with Pierre Duhem (1861-1916), a French physicist and historian and philosopher of science whose views were close to those of Henri Poincaré (1854-1912), who Ayer mentions later.

•  Chapter VI focuses on ethics, theology, and (briefly) aesthetics. Ayer has the most to say about the first of these topics, and it is probably the most useful focus for us. Much of what he has to say follows from the criterion of verifiability, but there are three further points here that are worth discussing.

•  The charge against subjectivism and utilitarianism Ayer makes on pp. 218-219 is very close in spirit to G. E. Moore’s idea of a “naturalistic fallacy” (i.e., the idea that it is fallacious to define “good” in terms of vocabulary describing the natural world). (In fact, Moore can be counted a utilitarian, but in a broader sense of the term than Ayer is assuming here.)

•  Ayer’s positive account of ethical vocabulary (pp. 220-222) shows the sort of function that might be ascribed to language that does not contribute to making factual assertions. Think not only about whether Ayer is right that ethics does not make factual statements but also about the functions Ayer ascribes to ethical language.

•  Finally, Ayer considers a possible problem for a “non-cognitivist” view of ethics, like Ayer’s: on a view like Ayer’s, how does one account for ethical arguments? Is Ayer’s answer to this question satisfactory?