Although I use this chapter and the next to pronounce on a number of the claims about explanation that I have described in the historical section of the book, there are two issues to which I want especially to attend. The first, which I tackle in this chapter, is the thesis common to Aristotle, Mill, and Hempel, that full explanations are valid arguments; the second, which I treat in Chapter VII, is Hempel’s view that some singular explanations are non-causal explanations. On the way to making these two points, something like a general view of explanation will emerge. That general view is put tentatively, and with some hesitation. I regard it more as a research project, than as a finished theory that is able, as it stands, to meet all difficulties.