Interpretation of Nominalism and Its Types

Nominalism is a metaphysical view in philosophy, the doctrine according to which abstract concepts, general terms or universals have no independent existence but exist only as names. Therefore, various objects labeled by the same term have nothing in common but their name. In other words, only actual physical particulars are real, and universals exist only subsequent to particular things, being just verbal abstractions.

Nominalism arose in reaction to the problem of universals and in particular to Plato's solution to it, known as Platonic Realism, which holds that abstract objects like universals and Forms exist in their own right and are wholly independent of the physical world, and that particular physical objects merely exemplify or instantiate the universal. Nominalists ask exactly where this universal realm might be, and find it unusual and unlikely that there could be a single thing that exists in multiple places simultaneously.

There have been attempts to bridge the gap between Realism and Nominalism including Moderate Realism (the view that there is no separate realm where universals or universal concepts exist, but that they are located in space and time wherever they happen to be manifest) and Conceptualism (the doctrine that universals exist only within the mind and have no external or substantial reality).

The Medieval French Scholastic philosopher and theologian Roscellinus of Compiegne (1050 – 1125), a teacher of Peter Abelard, is often regarded as the founder of modern Nominalism.

William of Ockham is also considered a pioneer of Nominalism, and he argued strongly that only individuals exist (rather than supra-individual universals, essences or forms), and that universals are the products of abstraction from individuals by the human mind and have no extra-mental existence. However, his view is perhaps more accurately described as Conceptualism rather than Nominalism, holding that universals are mental concepts (which do exist, even if only in the mind) rather than merely names (i.e. words rather than existing realities).

There are several types of Nominalism.

• Predicate Nominalism takes the linguistic line that, for example, two individual cats are both cats simply because the predicate "cat" applies to both of them (although to some extent this still begs the question of what the predicate actually applies to).

• Resemblance Nominalism holds that "cat" applies to both cats because they resemble an exemplar cat (an exemplar is a model or pattern to be copied or imitated) closely enough to be classed together with it as members of its kind, or that they differ less from each other (and other cats) than they differ from other things.

• Psychological Nominalism is the view in psychology that explains psychological concepts in terms of public language use.

R ationalism and Empiricism

Rationalism is a view emphasizing the role or importance of human reason. Rationalism starts from premises that cannot coherently be denied, then attempts by logical steps to deduce every possible object of knowledge.

The first rationalist is often held to be Parmenides, who argued that it is impossible to doubt that thinking actually occurs. But thinking must have an object; therefore something beyond thinking really exists. Parmenides deduced that what really exists must have certain properties. Zeno of Elea was a disciple of Parmenides, and argued against the reality of multiplicity and that motion is impossible. Plato was also influenced by Parmenides, but combined rationalism with a form of realism. The nature of a man, a triangle, a tree, applies to all men, all triangles, and all trees. Plato argued that these essences are mind-independent ‘forms’ that humans (but particularly philosophers) can come to know by reason, and by ignoring the distractions of sense-perception.

Modern rationalism begins with Descartes. Reflection on the nature of perceptual experience, as well as scientific discoveries in physiology and optics, led Descartes (and also Locke) to the view that we are directly aware of ideas, rather than objects. He began, echoing Parmenides, with a principle that he thought could not coherently be denied: I think, therefore I am (often given in his original Latin: Cogito ergo sum). From this principle, Descartes went on to construct a complete system of knowledge (which involves proving the existence of God, using, among other means, a version of the ontological argument). His view strongly influenced those philosophers usually considered modern rationalists such as Baruch Spinoza, Gottfried Leibniz, and Christian Wolff.

Empiricism is the belief that all knowledge comes from experience. The "empirical world" is the world of the senses, i.e. the world we can see, feel, touch, hear and smell. Empiricism, in contrast to rationalism, downplays or dismisses the ability of reason alone to yield knowledge of the world, preferring to base any knowledge we have on our senses. John Locke propounded the classic empiricist view in An Essay Concerning Human Understanding in 1689, developing a form of naturalism and empiricism on roughly scientific (and Newtonian) principles. John Locke thought that the human mind at birth was a tabula rasa on which experience writes the general principles and details of all knowledge. This is completely opposite to the rationalists. Whereas a rationalist would attempt to find knowledge by thought alone, an empiricist would use the methods of the experimental sciences.