The subject of this study is an ambiguity which is deeply rooted in Berkeley's arguments against matter. By a is shift between two meanings of the term ‘sensible’, he is able to construct a simple “refutation” of matter. Berkeley then attempts to show that this argument is irrefutable. The ambiguity of the original argument is, however, contained in the train of supporting arguments. My purpose in bringing attention to this ambiguity is not just to reveal a mistake in Berkeley's arguments (...) against matter. This particular mistake, I believe, deserves scrutiny not only because it is a mistake, but also because it explains the strategy and order of Berkeley's arguments against matter. Furthermore, if this explanation is correct, then some light can be cast on some puzzling features of Berkeley's philosophy. (shrink)