Chapman generally does, yes; his most explicit definition for “rationality” in his sense is on this page:
The book uses “rationality” to refer to systematic, formal methods for thinking and acting; not in the broader sense of “any sensible way of thinking or acting,” as opposed to irrationality. [...]
Meanings of “rational” have multiplied and evolved over centuries, which can create confusion. In the broadest sense, it’s synonymous with “sensible.” In some narrow senses, it means using a specific mathematical system to decide what to do.
I will use it in an intermediate sense: rational methods are formal, systematic, explicit, technical, abstract, atypical, non-obvious ways of thinking and acting, which have some distinctive virtue relative to informal ones.1 “Methods” suggests that rationality is a practical activity: things we actually do, rather than a metaphysical ideal we should aspire to.
“Systematic” and “formal” are key criteria, but both are nebulous. They are a matter of degree. Mathematical logic is extremely formal; a chemistry methods manual is quite formal; a corporate personnel policy is somewhat formal; a “Do Today” task checklist is only barely formal. “System” is used vaguely to mean almost anything complicated. I’ll use it a little more specifically, as meaning a set of rules that can be printed in a book, which a person can consciously follow, and the activities and mechanisms that result.
Rationality works mainly with general knowledge. Ideally, it aims for universal truths. Typically, knowledge of a specific object does not count as “rational” unless it applies to every other object in some class. The glory of Newton’s theory of gravity is that it is true uniformly everywhere in the universe, equally for an apple and an asteroid.
Chapman generally does, yes; his most explicit definition for “rationality” in his sense is on this page: