Metaphilosophy, sometimes called the philosophy of philosophy, is "the investigation of the nature of philosophy". Its subject matter includes the aims of philosophy, the boundaries of philosophy, and its methods. Thus, while philosophy characteristically inquires into the nature of being, the reality of objects, the possibility of knowledge, the nature of truth, and so on, metaphilosophy is the self-reflective inquiry into the nature, aims, and methods of the activity that makes these kinds of inquiries, by asking what is philosophy itself, what sorts of questions it should ask, how it might pose and answer them, and what it can achieve in doing so. It is considered by some to be a subject prior and preparatory to philosophy, while others see it as inherently a part of philosophy, or automatically a part of philosophy while others adopt some combination of these views.

The interest in metaphilosophy led to the establishment of the journal Metaphilosophy in January 1970.

Many sub-disciplines of philosophy have their own branch of 'metaphilosophy', examples being meta-aesthetics, meta-epistemology, meta-ethics, and metametaphysics (meta-ontology).

Although the term metaphilosophy and explicit attention to metaphilosophy as a specific domain within philosophy arose in the 20th century, the topic is likely as old as philosophy itself, and can be traced back at least as far as the works of Ancient Greeks and Ancient Indian Nyaya.

Some philosophers consider metaphilosophy to be a subject apart from philosophy, above or beyond it, while others object to that idea. Timothy Williamson argues that the philosophy of philosophy is "automatically part of philosophy", as is the philosophy of anything else. Ludwig Wittgenstein argued that there is no "second-order philosophy" in the same way an explanation of the spelling of "spelling" is not second-order spelling, or orthography of the word 'orthography' is not second-order orthography. Nicholas Bunnin and Jiyuan Yu write that the separation of first- from second-order study has lost popularity as philosophers find it hard to observe the distinction. As evidenced by these contrasting opinions, debate persists as to whether the evaluation of the nature of philosophy is 'second-order philosophy' or simply 'plain philosophy'.

Many philosophers have expressed doubts over the value of metaphilosophy. Among them is Gilbert Ryle: "preoccupation with questions about methods tends to distract us from prosecuting the methods themselves. We run as a rule, worse, not better, if we think a lot about our feet. So let us ... not speak of it all but just do it."

The designations metaphilosophy and philosophy of philosophy have a variety of meanings, sometimes taken to be synonyms, and sometimes seen as distinct.

Morris Lazerowitz claims to have coined the term 'metaphilosophy' around 1940 and used it in print in 1942. Lazerowitz proposed that metaphilosophy is 'the investigation of the nature of philosophy'. Earlier uses have been found in translations from French. The term is derived from Greek word meta μετά ("after", "beyond", "with") and philosophía φιλοσοφία ("love of wisdom").