Applied philosophyThough often seen as a wholly abstract field, philosophy is not without practical applications. The most obvious applications are those in ethics – applied ethics in particular – and in political philosophy. The political philosophies of Confucius, Kautilya, Sun Zi, Immanuel Kant, John Locke, Thomas Hobbes, Niccolò Machiavelli, Jean-Jacques Rousseau, Karl Marx, John Stuart Mill, Mahatma Gandhi, Robert Nozick, and John Rawls have shaped and been used to justify the existence of governments and their actions.

In the field of the philosophy of education, progressive education as championed by John Dewey has had a profound impact on educational practices in the United States in the twentieth century. Carl von Clausewitz's political philosophy of war has had a profound effect on statecraft, international politics and military strategy in the 20th century, especially in the years around World War II.

Other important applications can be found in epistemology, which aid in understanding the notions of what knowledge, evidence, and justified belief are. The philosophy of science discusses the underpinnings of the scientific method. Aesthetics can help to interpret discussions of art. Ontology, even within the artificial intelligence definition, has had important consequences for logic and computer science.

In general, the various "philosophies of..." such as the philosophy of law, can provide workers in their respective fields with a deeper understanding of the theoretical or conceptual underpinnings of their fields.

Often philosophy is seen as an investigation into an area not understood well enough to be its own branch of knowledge. What were once philosophical pursuits have evolved into the modern day fields of psychology, sociology, linguistics, and economics (among others).

The idea of philosophy as general concepts or principles of knowledge breaks down in fields of endeavor which require a certain type or level of personal performance. For instance, no principles of knowledge can tell a person how to write dramatic works comparable in quality to Shakespeare's or symphonies comparable to Beethoven's or to hit baseballs like Babe Ruth or sing songs like Elvis Presley. Yet, there is a certain state of mind conducive to peak performance in such fields. Sports psychology does bring knowledge to bear upon such endeavors. William McGaughey's book, "Rhythm and Self-Consciousness", approaches rhythm as a philosophical concept, discussing both its conscious pursuit and its limitations. Confines of PhilosophyWhat should, and what should not, be counted as philosophy, has been heavily debated by many philosophers through the ages. See also pseudophilosophy.

Relativists may claim that any statement can be counted as a philosophical statement, as there is no objective way to disqualify it of being so. Also, the very open-minded nature of philosophy makes many people sceptical when it comes to limiting the concept of philosophy to something tangible and not something open-ended. However, several philosophers or philosophical directions have had ideas about what philosophy is and what it should not be.

Plato, or the protagonist in his dialogues, Socrates, who arguably coined the term, held up a number of virtues for anyone who wanted to call themselves a philosopher. Amongst other things, he rejected that rhetorics had a place in philosophy, most famously in Gorgias.

The logical positivists denied the soundness of metaphysics and traditional philosophy, and affirmed that statements about metaphysics, religion and ethics are devoid of cognitive meaning and thus nothing but expression of feelings or desires.

What constitutes sound philosophical work is sometimes summed up by the term Philosophical method. Also, it is often agreed upon that arguments should try to avoid vague, non-defined or ill-defined concepts; avoid mixing together different concepts that share the same term; avoid heavy use of concepts with strong connotations; and being logically sound. It has also been argued that the scientific method should be followed as closely as the subject-matter allows. When a branch of philosophy at some point fully can start following the norms of the scientific method, it is no longer termed philosophy, but science. Philosophers on PhilosophyWhat is philosophy? Some would respond by listing its major subfields such as logic, ethics, and epistemology; on the other hand, it has also been said that "philosophy is the study of its own history" (viz., its own literature). However, some noted philosophers have attempted to address these issues central to philosophy's subject matter and how it is treated:

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