[Philosophy's] task is to resolve philosophical problems. The characteristic feature of philosophical problems is their non-empirical, a priori character: no scientific experiment can settle the question of whether the mind is the brain, what the meaning of a word is, whether human beings are responsible for their deeds (have free will), whether trees falling on uninhabited desert islands make any noise, what makes necessary truths necessary. All these, and many hundreds more, are conceptual questions. They are not questions about concepts (philosophy is not a science of concepts). But they are questions that are to be answered, resolved or dissolved by careful scrutiny of the concepts involved. The only way to scrutinize concepts is to examine the use of the words that express them. Conceptual investigations are investigations into what makes sense and what does not. And, of course, questions of sense antecede questions of empirical truth – for if something makes no sense, it can be neither true nor false. It is just nonsense – not silly, but rather: it transgresses the bounds of sense. Philosophy patrols the borders between sense and nonsense; science determines what is empirically true and what is empirically false. What falsehood is for science, nonsense is for philosophy.
Hacker's claims raise many interesting questions:
- How can philosophical questions have "a non-empirical, a priori character"? Does Hacker mean the answers to philosophical questions? If so, does that mean that any question whose answer is a non-empirical, a priori answer must be a philosophical question (and, conversely, any question whose answer is empirical must be a non-philosophical question)?
- Why do scientific experiments have to "settle" philosophical questions? Can't they simply tilt the balance in favor of one answer or another?
- If philosophical questions are "not questions about concepts," they what are they about?
- If "the only way to scrutinize concepts is to examine the use of the words that express them," and "conceptual investigations are investigations into what makes sense and what does not," and philosophy is conceptual investigation, then wouldn't it follow that any conceptual investigation will necessarily result in "sense" rather than "nonsense"? For, if we're already using a word, doesn't that mean that it makes (at least some) sense to us? If so, how can philosophy ever show that something is nonsensical?