Metaphysics

Metaphysics is the study of the most general features of reality, such as existence, time, the relationship between mind and body,objects and their properties, wholes and their parts, events, processes, and causation. Traditional branches of metaphysics include cosmology, the study of the world in its entirety, and ontology, the study of being.

Within metaphysics itself there are a wide range of differing philosophical theories. Idealism, for example, is the belief that reality is mentally constructed or otherwise immaterial while realism holds that reality, or at least some part of it, exists independently of the mind. Subjective idealism describes objects as no more than collections or "bundles" of sense data in the perceiver. The 18th century philosopher George Berkeley contended that existence is fundamentally tied to perception with the phrase Esse est aut percipi aut percipere or "To be is to be perceived or to perceive".

In addition to the aforementioned views, however, there is also an ontological dichotomy within metaphysics between the concepts of particulars and universals as well. Particulars are those objects that are said to exist in space and time, as opposed to abstract objects, such as numbers. Universals are properties held by multiple particulars, such as redness or a gender. The type of existence, if any, of universals and abstract objects is an issue of serious debate within metaphysical philosophy. Realism is the philosophical position that universals do in fact exist, while nominalism is the negation, or denial of universals, abstract objects, or both.Conceptualism holds that universals exist, but only within the mind's perception.

The question of whether or not existence is a predicate has been discussed since the Early Modern period. Essence is the set of attributes that make an object what it fundamentally is and without which it loses its identity. Essence is contrasted with accident: a property that the substance has contingently, without which the substance can still retain its identity.