I have been going back over my review of Philosophy of Science in Practice: Nancy Cartwright and the Nature of Scientific Reasoning , and want to note an interesting problem, or perhaps pseudo-problem, that I did not have space to bring up in the review. Roman Frigg and James Nguyen, in their essay in the reviewed work, have a very enlightening discussion of how scientific models "represent" some phenomenon. (Roman was one of my lecturers when I studied the philosophy of science at the LSE, and an excellent lecturer at that, so I hope he will forgive my pun on his name in the post title! Also, I am writing this post without the book in front of me, so I beg forgiveness if my rendition of the authors' terminology is not exact.) Frigg and Nguyen's primary criterion for how a scientific model represents is that it is "declared" to represent some class of events: for example, a histogram of adult heights in the United States represents those heights becaus...