Although this paper was written more than 30 years ago, Paul Thagard (1950-) is a much more recent philosopher than Russell or Popper, and what he writes here anticipates some ideas we will encounter later. In particular, he has in mind some criticisms of falsificationism that we will encounter in Kuhn.
Thagard’s discussion gives a brief account of astrology, surveys and criticizes views of others about why astrology is a pseudoscience, and then offers and defends his own view. (In the page references to follow, the pages of the version in KHR are given first followed, in square brackets, by the pages in the original version, which is on JSTOR; the page breaks in the two versions tend to be within a few lines of one another.)
• One thing to note about Thagard’s account of astrology (pp. 66-67 [223-224]) is its history, in particular how it once attracted the attention of very serious scientists. Also note the point at which it ceased to do so, for this will also prove significant later.
• Thagard considers two groups of accounts of why astrology is a pseudoscience. The first group is dismissed rather quickly (pp. 67-68 [224-225]), but you should decide for yourself whether he is right to dismiss them.
He next considers criteria of verifiability and falsifiability (pp. 68-69 [225-226]). The first is a sort of inductivist criterion according to which a theory is scientific if it is sensitive to empirical evidence in the sense that it is clear what evidence would confirm it by increasing its probability and what evidence would “disconfirm” it by reducing its probability.
When speaking of “falisfiability,” Thagard has in mind Popper’s view of what counts as science. The people he mentions as critics of falsificationism are all significant figures: Duhem is one of the “conventionalists” Popper referred to, Quine (1908-2000), who we will read a little from later, is a more recent philosopher with somewhat similar views, and Lakatos (1922-1974) is a philosopher who was influenced by both Popper and Kuhn. When considering Thagard’s criticisms of falsificationism, you should think in particular about the idea that it is not reasonable to abandon a scientific theory unless there is an alternative available. (The passage about the corrigibility of observation statements that Thagard cites from Popper’s Logic of Scientific Discovery is one of those on your handout.)
• Thagard’s own account of why astrology is a pseudoscience is developed on pp. 70-72 [227-229]. One of the ways that Thagard explains his view is to contrast it with those of Kuhn and Lakatos. Thagard tends to assume his reader is familiar with Kuhn and Kuhn’s idea of normal science; but, in reporting a comment by Watkins (p. 71 [228]), he gives a good enough account of what Kuhn means by this term that you can work from it.
• In the two paragraphs before the final concluding paragraph (pp. 72-73 [229-230]), Thagard considers two possible problems for or objections to his view. Do you think he deals with them successfully?