Much of what was once in the province of philosophy now belongs to the sciences. Might it be that eventually everything once claimed by philosophy will be taken over by special sciences? I recently took Lawrence Krauss to task here and here for his latest scientistic outburst according to which philosophical problems, "when the grow up, leave home." He maintains that all answerable questions belong in the domain of empirical science. Is that right? Is it true that, eventually, there will nothing left for philosophy to do? Or are there certain problems and questions that will remain specifically philosophical? I suggest that in the following four areas philosophy has and will retain its proprietary rights in perpetuity.
A. Metaphilosophical Questions. Let us first note that the questions raised in my introductory paragraph belong to philosophy. They are questions about philosophy. All such metaphilosophical questions belong to philosophy. The philosophy of science (religion, law, etc.) is not part of science (religion, law, etc.), but the philosophy of philosophy is a branch of philosophy. There is simply no more encompassing rational discipline than philosophy. So right here we have a number of questions that do not belong to any empirical science or to any formal science such as mathematics either. (Whether or not you want to call mathematics science, it is certainly not empirical science.)
Consider the question of scientism. When properly employed, the term 'scientism' means the following.
Scientism is a philosophical thesis that belongs to the sub-discipline of epistemology. It is not a thesis in science, but a thesis about science. The thesis in its strongest form is that the only genuine knowledge is scientific knowledge, the knowledge generated by the (hard) sciences of physics, chemistry, biology and their offshoots. The thesis in a weaker form allows some cognitive value to the social sciences, the humanities, and other subjects, but insists that scientific knowledge is vastly superior and authoritative and is as it were the 'gold standard' when it comes to knowledge. On either strong or weak scientism, there is no room for first philosophy, according to which philosophy is an autonomous discipline, independent of natural science, and authoritative in respect to it. So on scientism, natural science sets the standard in matters epistemic, and philosophy’s role is at best ancillary. Not a handmaiden to theology in this day and age; a handmaiden to science.
The question whether scientism is true is a philosophical question that cannot by its very nature be answered by any empirical science. Not only is this question not discussed in any physics or chemistry or biology text, it is not a question to the answering of which observation and experiment are at all relevant. The question whether the only genuine knowledge is scientific knowlerdge is not an empirical question. It is not like the question whether high sodium intake is a contributing factor in hypertension or whether galactic recession is taking place.
Those who champion scientism are doing philosophy whether they know it or not, and presupposing that there are specifically philosophical theses. For scientism is a philosophical thesis. Not only is scientism a philosophical thesis, it is an untenable philosophical thesis (as I argue here) the critique of which belongs to philosophy. Both the forwarding of the thesis and its evaluation as untenable are specifically philosophical activities. One of the perennial tasks of philosophy is the debunking of bad philosophy or pseudo-philosophy of the sort produced by ignorant people like Krauss.
B. Normative Questions. There are normative questions of various sorts in logic, epistemology, aesthetics, ethics, and politology. Empirical investigation cannot answer normative questions. Consider the theory of the state. A good chunk of it will be covered by political science which, perhaps, is independent of philosophy. Political science studies the types, characteristics, institutions, and genesis of states and other political entities as they actually exist. It is a non-normative enterprise devoted to facts and their explanation. It will of course treat of the norms embedded in laws and institutions but will study these norms as facts. One can study the content of legal prescriptions and proscriptions under bracketing of their rightness or wrongness. To do so is to study them as facts. Thus one could study the content of the Nazi state's Nuremberg Laws without raising the question of their justice or injustice. Questions about the moral legitimacy of a given state or of any state are quite different from the factual questions treated in political science: they are normative questions belonging to political philosophy. If I study the structure of the Nazi state and its institutions and hierarchies I am doing political science. But if I argue that the Nazi state was a criminal state or an unjust state then I have moved into the normative dimension and am doing political philosophy.
Or consider logic. It does not reduce to the psychology of reasoning, let alone to the neurobiology underlying reasoning. It is a normative discipline concerned, not with how we think as a matter of fact, but how we ought to think if we are to arrive at truth. Similar considerations hold for epistemology, aesthetics, and ethics. Suppose you disagree with what I just said about logic. Then we have a dispute in the philosophy of logic, and once again philosophy is seen to be indispensable.
3. Critical Questions. One can raise critical questions about religion, mysticism, law, science and other sectors of culture. A critique of religion, for example, aims to separate out the true from the false and the beneficial from the harmful in religion. It aims to evaluate religion as a cultural form. This is different from the descriptive study of extant religions. A critique of Buddhism, for example, goes beyond a study of characteristic Buddhist beliefs and practices; it is concerned to evaluate these beliefs and practices in the light of such criteria as logical coherence, truth, and whether they help or hinder human flourishing. Such an evaluation is obviously a specifically philosophical enterprise. It cannot be supplanted by the sociology or psychology of Buddhism. Suppose it is established that Buddhism appeals to people of a certain psychological make-up or social class. That is an interesting fact, but is irrelevant to the question whether Buddhism is wholly or in part logically coherent, true, or conducive to human flourishing. The critique of Buddhism, and of any religion, belongs to philosophy. And the same goes for the critique of mysticism, law, and the rest.
4. Metaphysical Questions. These are non-normative but also non-empirical questions. They have no place within the province of any empirical science.
There are the questions of general metaphysics or ontology. Among them: questions about existence, identity, properties, relations, modality. Consider these two claims:
a. Principle of the Rejection of Nonexistent Objects: Necessarily, for any x, if x has properties, then x exists.
b. Principle of the Rejection of Unpropertied Objects: Necessarily, for any x, if x exists, then x has properties.
I say both are true propositions of general metaphysics. They are items of knowledge about the structure of any possible world, and therefore items of knowledge about the structure of the actual world. But we do not know them by any empirical method: they do not belong in an empirical science.
The principles are not truths of pure logic either. For their negations are not logical contradictions. They are irreducibly ontological truths. The belong to metaphysca generalis or ontology.
The Meinongians deny (a). Where does the dispute about (a) belong? In physics? You would have to be as thoughtless as Krauss to maintain such a thing. It belongs nowhere else but in philosophy.
There are also the questions of special metaphysics, among them, questions about God, the soul, the freedom of the will, and the relationof mind and body.