Halvorson’s book’s real achievement is that it is both a source and a challenge, and not just for philosophers of science. I will begin with some notes to add to Halvorson’s discussion of supervenience and definability. Then secondly I will engage the book’s way of dealing with empirical content. Extension of formal methods to the relation of theory to world, as mediated by experiment and measurement, seems to me crucial to its value, and I will make three suggestions for this. Then thirdly I will turn to the tantalizing hints Halvorson gives us of an overall view of logic and language, and speculate about how that would answer questions about scientific representation and more specifically about the object language / metalanguage relation
