Willard Van Orman Quine (1908-2000) was born about the same time as Hempel and was one of the most important American philosophers of the second half of the 20th century. This selection is a chapter from a textbook, The Web of Belief, that he wrote with one of his students.

Quine and Ullian, like Carnap, introduce the idea of hypothesis by contrast with generalization. But their interest is less in the source and nature of theories than in how they are justified. Their account of that takes the form of a list of “virtues” a theory might have. They don’t speak of induction in this chapter and, when they go to consider it in the next one, they describe it as “a case of hypothesis” (Web of Belief, p. 58) and associate it especially with the virtues of hypotheses that they number II and III.

One question to ask yourself is how close Quine and Ullian’s approach to justification is to Giere’s. And the best way of approaching that question is probably to ask yourself what they might say about his examples. Approaches like theirs are often described using the terms “inference to the best explanation” or “abduction” (the latter term was popularized by an important American philosophy of the latter part of the 19th century, Charles Sanders Peirce, 1839–1914, who was also the source of the movement pragmatism).

Quine and Ullian will discuss examples of the sort discussed by Popper and Thagard, and you should also think about the relation of what Quine and Ullian say (about astrology, for example) to what Popper or Thagard would, or do, say.