  The view sketched above has both positive and negative aspects. The latter are better-known, and Quine is often thought of as a negative philosopher, primarily concerned to criticize others. He casts doubt on terms which many philosophers take for granted. He does not dismiss such terms as meaningless, but simply as not meriting a place in serious science, or in the objective account of the world at which science aims. A well-known and important example is his criticism of the idea of meaning, in the sense of the meaning of a particular sentence or statement. Quine says: “Meaning… is a worthy object of philosophical and scientific clarification and analysis, and… it is ill-suited for use as an instrument of philosophical and scientific clarification and analysis.” (1981, 185). The term is insufficiently clear, and putative explanations which employ it are in fact unexplanatory; by engendering the illusion of explanation they tend to impede the progress of science. So philosophers should not rely on the term. He makes similar remarks about “thought”, “belief”, “experience”, “necessity”, and other terms which many philosophers assume are legitimate and available for philosophical use without themselves requiring explanation and justification in other terms. (For an illustration of Quine’s attitude towards the term “meaning” as used by one such philosopher, see his reply to Pagin in Orenstein and Kokato, 420f.)