<P> On the one hand, ontology is the study of being, and the central topic of the field is couched, variously, in terms of being, existence, "what is", and reality . The task in ontology is to describe the most general categories of reality and how they are interrelated . If a philosopher wanted to proffer a positive definition of the concept "reality", it would be done under this heading . As explained above, some philosophers draw a distinction between reality and existence . In fact, many analytic philosophers today tend to avoid the term "real" and "reality" in discussing ontological issues . But for those who would treat "is real" the same way they treat "exists", one of the leading questions of analytic philosophy has been whether existence (or reality) is a property of objects . It has been widely held by analytic philosophers that it is not a property at all, though this view has lost some ground in recent decades . </P> <P> On the other hand, particularly in discussions of objectivity that have feet in both metaphysics and epistemology, philosophical discussions of "reality" often concern the ways in which reality is, or is not, in some way dependent upon (or, to use fashionable jargon, "constructed" out of) mental and cultural factors such as perceptions, beliefs, and other mental states, as well as cultural artifacts, such as religions and political movements, on up to the vague notion of a common cultural world view, or Weltanschauung . </P> <P> The view that there is a reality independent of any beliefs, perceptions, etc., is called realism . More specifically, philosophers are given to speaking about "realism about" this and that, such as realism about universals or realism about the external world . Generally, where one can identify any class of object, the existence or essential characteristics of which is said not to depend on perceptions, beliefs, language, or any other human artifact, one can speak of "realism about" that object . </P> <P> One can also speak of anti-realism about the same objects . Anti-realism is the latest in a long series of terms for views opposed to realism . Perhaps the first was idealism, so called because reality was said to be in the mind, or a product of our ideas . Berkeleyan idealism is the view, propounded by the Irish empiricist George Berkeley, that the objects of perception are actually ideas in the mind . In this view, one might be tempted to say that reality is a "mental construct"; this is not quite accurate, however, since, in Berkeley's view, perceptual ideas are created and coordinated by God . By the 20th century, views similar to Berkeley's were called phenomenalism . Phenomenalism differs from Berkeleyan idealism primarily in that Berkeley believed that minds, or souls, are not merely ideas nor made up of ideas, whereas varieties of phenomenalism, such as that advocated by Russell, tended to go farther to say that the mind itself is merely a collection of perceptions, memories, etc., and that there is no mind or soul over and above such mental events . Finally, anti-realism became a fashionable term for any view which held that the existence of some object depends upon the mind or cultural artifacts . The view that the so - called external world is really merely a social, or cultural, artifact, called social constructionism, is one variety of anti-realism . Cultural relativism is the view that social issues such as morality are not absolute, but at least partially cultural artifact . </P>

The view that everything that exists is physical is known as