She has worked on problems in analytic philosophy, the interpretation of Ludwig Wittgenstein, and moral philosophy. A moral vegetarian, she has also examined the rhetorical and philosophical nature of contemporary attitudes towards animal rights. An article of hers, What Nonsense Might Be, criticizes the way that the logical positivists think about nonsense on Fregean grounds. (See category mistake.) Her writings on both "early" (Tractatus Logico-Philosophicus era) and "late" (Philosophical Investigations era) Wittgenstein have made her the leading influence on the New Wittgenstein taken up by James F. Conant, Thomas Ricketts and others.