 The two approaches to QFT continue to develop in parallel. Fleming (2002, pp. 135–136) brings this into focus in his discussion of differences between Haag’s Local Quantum Physics (1996) and Weinberg’s Quantum Field Theory (1995); Haag’s book presents algebraic QFT, and Weinberg’s book presents Lagrangian QFT. While both books are ostensibly about the same subject, Haag gives a precise formulation of QFT and its mathematical structure, but does not provide any techniques for connecting with experimentally determined quantities, such as scattering cross sections. Weinberg gives a pragmatic formulation that engages with physical intuition and provides heuristics that are important for performing calculations; however, it is not as mathematically rigorous. Moreover, there are a number of important topics that are examined in one book while not even mentioned in the other. For example, unitarily inequivalent representations are discussed by Haag, but not by Weinberg. By contrast, Weinberg discusses Feynman’s rules for path integrals, which are not mentioned at all by Haag. There is also the issue of demographics. Most particle and experimental physicists will read and study Weinberg’s book, but very few will read Haag’s book. Because of these differences, Fleming (2002, p. 136) suggests that one might question whether the two books are really about the same subject. This gives rise to the question whether any formulation of QFT is worthy of philosophical attention to its foundations. In particular, there is a debate between Wallace (2006, 2011) and Fraser (2009, 2011) over whether an interpretation of QFT should be based on the standard textbook treatment of QFT or an axiomatic formulation of QFT.