Definitions of philosophy
Definitions of philosophy aim at determining what all forms of philosophy have in common and how to distinguish philosophy from other disciplines. Many different definitions have been proposed but there is very little agreement on which is the right one. Some general characteristics of philosophy are widely accepted, for example, that it is a form of rational inquiry that is systematic, critical, and tends to reflect on its own methods. But such characteristics are usually too vague to give a proper definition of philosophy. Many of the more concrete definitions are very controversial, often because they are revisionary in that they deny the label philosophy to various subdisciplines for which it is normally used. Such definitions are usually only accepted by philosophers belonging to a specific philosophical movement. One reason for these difficulties is that the meaning of the term "philosophy" has changed throughout history: it used to include the sciences as its subdisciplines, which are seen as distinct disciplines in the modern discourse. But even in its contemporary usage, it is still a wide term spanning over many different subfields.
An important distinction among approaches to defining philosophy is between deflationism and essentialism. Deflationist approaches see it as an empty blanket term, while essentialistic approaches hold that there is a certain set of characteristic features shared by all parts of philosophy. Between these two extremes, it has been argued that these parts are related to each other by family resemblance even though they do not all share the same characteristic features. Some approaches try to define philosophy based on its method by emphasizing its use of pure reasoning instead of empirical evidence. Others focus on the wideness of its topic, either in the sense that it includes almost every field or based on the idea that it is concerned with the world as a whole or the big questions. These two approaches may also be combined to give a more precise definition based both on method and on topic.
Many definitions of philosophy concentrate on its close relation to science. Some see it as a proper science itself, focusing, for example, on the essences of things and not on empirical matters of fact, in contrast to most other sciences, or on its level of abstractness by talking about very wide-ranging empirical patterns instead of particular observations. But since philosophy seems to lack the progress found in regular sciences, various theorists have opted for a weaker definition by seeing philosophy as an immature science that has not yet found its sure footing. This position is able to explain both the lack of progress and the fact that various sciences used to belong to philosophy, while they were still in their provisional stages. It has the disadvantage of degrading philosophical practice in relation to the sciences.
Other approaches see philosophy more in contrast to the sciences as concerned mainly with meaning, understanding, or the clarification of language. This can take the form of the analysis of language and how it relates to the world, of finding the necessary and sufficient conditions for the applications of technical terms, as the task of identifying what pre-ontological understanding of the world we already have and which a priori conditions of possibility govern all experience, or as a form of therapy that tries to dispel illusions due to the confusing structure of natural language. An outlook on philosophy prevalent in the ancient discourse sees it as the love of wisdom expressed in the spiritual practice of developing one's reasoning ability in order to lead a better life. A closely related approach holds that the articulation of worldviews is the principal task of philosophy. Other conceptions emphasize the reflective nature of philosophy, for example, as thinking about thinking or as an openness to questioning any presupposition.
General characteristics and sources of disagreement
The problem of defining philosophy concerns the question of what all forms of philosophy have in common, i.e. how philosophy differs from non-philosophy or other disciplines, such as the empirical sciences or fine art. One difficulty is due to the fact that the meaning of the term "philosophy" has changed a lot in history: it was used in a much wider sense to refer to any form of rational inquiry before the modern age. In this sense, it included many of the individual sciences and mathematics, which are not seen as part of philosophy today. For example, Isaac Newton's Philosophiæ Naturalis Principia Mathematica formulating the laws of classical mechanics carries the term in its title. Modern definitions of philosophy, as discussed in this article, tend to focus on how the term is used today, i.e. on a more narrow sense. Some basic characterizations of philosophy are widely accepted, like that it is a critical and mostly systematic study of a great range of areas. Other such characterizations include that it seeks to uncover fundamental truths in these areas using a reasoned approach while also reflecting on its own methods and standards of evidence. Such characterizations succeed at characterizing many or all parts of philosophy, which is a wide discipline spanning across many fields, as reflected in its sub-disciplines termed "philosophy of...", like the philosophy of science, of mind, of law, of religion, or of pornography. One difficulty for this type of approach is that it may include non-philosophical disciplines in its definition instead of distinguishing philosophy from them.To overcome these difficulties, various more specific definitions of philosophy have been proposed. Most of them are controversial. In many cases, they are only accepted by philosophers belonging to one philosophical movement but not by others. The more general conceptions are sometimes referred to as descriptive conceptions in contrast to the more specific prescriptive conceptions. Descriptive conceptions try to give an account of how the term "philosophy" is actually used or what philosophers in the widest sense do. Prescriptive conceptions, on the other hand, aim at clarifying what philosophy ideally is or what it ought to be, even if what philosophers actually do often fall behind this ideal. This issue is particularly controversial since different philosophical movements often diverge widely in what they consider to be good philosophy. They are often revisionistic in the sense that many presumed parts of philosophy, past and present, would not deserve the title "philosophy" if they were true.
Some definitions of philosophy focus mainly on what the activity of doing philosophy is like, such as striving towards knowledge. Others concentrate more on the theories and systems arrived at this way. In this sense, the terms "philosophy" and "philosophical" can apply both to a thought process, to the results of this activity in the form of theories, or even to contemplative forms of life reflecting such theories. Another common approach is to define philosophy in relation to the task or goal it seeks to accomplish such as answering certain types of questions or arriving at a certain type of knowledge.
The difficulty in defining "philosophy" is also reflected in the fact that introductions to philosophy often do not start with a precise definition but introduce it instead by providing an overview of its many branches and subfields, such as epistemology, ethics, logic, and metaphysics. The discipline known as metaphilosophy has as one of its main goals to clarify the nature of philosophy. Outside the academic context, the term "philosophy" is sometimes used in an unspecific sense referring to general ideas or guidelines, such as the business philosophy of a company, the leadership philosophy of an entrepreneur, or the teaching philosophy of a schoolmaster.
Deflationism, essentialism, and family resemblance
An important distinction among definitions of philosophy is between deflationism and essentialism. The deflationist approach holds that philosophy is an empty blanket term. It is used for convenience by deans and librarians to group various forms of inquiry together. This approach is usually motivated by the enduring difficulties in giving a satisfying definition. According to this view, philosophy does not have a precise essence shared by all its manifestations. One difficulty with the deflationist approach is that it is not helpful for solving disagreements on whether a certain new theory or activity qualifies as philosophy since this would seem to be just a matter of convention. Another is that it implies that the term "philosophy" is rather empty or meaningless.This approach is opposed by essentialists, who contend that a set of features constitutes the essence of philosophy and characterizes all and only its parts. Many of the definitions based on subject matter, method, its relation to science or to meaning and understanding are essentialists conceptions of philosophy. They are controversial since they often exclude various theories and activities usually treated as part of philosophy.
These difficulties with the deflationist and the essentialist approach have moved some philosophers towards a middle ground, according to which the different parts of philosophy are characterized by family resemblances. This means that the various parts of philosophy resemble each other by sharing several features. But different parts share different features with each other, i.e. they do not all share the same features. This approach can explain both that the term "philosophy" has some substance to it, i.e. that it is not just based on an empty convention, and that some parts of philosophy may differ a lot from each other, for example, that some parts are very similar to mathematics while others almost belong to the natural sciences and psychology. This approach has the disadvantage that it leaves the definition of philosophy vague, thereby making it difficult for the non-paradigmatic cases to determine whether they belong to philosophy or not, i.e. that there is no clear-cut distinction.