That Philosophy Website

The Forms (Plato)

Information: This article sets out the key feature of Plato's understanding of the Forms. For a more detailed discussion of this subject see Plato and the Forms: Overview and analysis. All quotations are from The Republic. A version of this article was originally published on the website www.faithnet.org.uk.

The necessity of the Forms in Plato's theory of knowledge is a somewhat controversial aspect of his philosophy, yet one he appears to assume his audience is both familiar with and accepting of. As such, there is no specific 'theory of the Forms' set out in any of his works. Instead, our understanding of the nature and purpose of the Forms is based on various references Plato makes to them in several of his works.

In The Republic (Plato's most well-known work), the Forms are said to underpin all that Plato has to say about society, Justice, and the nature of a true and Just ruler (aka Philosopher-Kings). In fact, Plato believes the qualities of the Forms should be reflected in the disposition of the ideal ruler, which is deemed to make them fit to rule:

'His eyes are turned to contemplate fixed and immutable realities, a realm where there is no injustice done or suffered, but all is reason and order, and which he assimilates himself [to this way of living] as far as he can.'

Plato assumes that if we understand (and accept) what the Forms are, then we too will be on the right path to understanding the true nature of Justice and living the good life.

Plato believes the Forms are the unique and immutable (unchanging and unchangeable) source of knowledge. However, in order get a better understanding of what he understood them to be, we will consider two arguments he put forward to justify (and support) their existence.

The one over many argument is the idea that if we want to speak of x, then there must be some ultimate standard (or Form) of x. For example, we might talk of 'shades of green', but what is Green? Well, to speak of 'shades of green' we are suggesting there is some source of green from which all the shades derive. Also, the fact that we speak of shades of green means we know there is a standard by which these all shades are judged to be green by.

Of course, the question begs as to which one (if any) of the 'shades of green' is actually Green? For instance, if we were to choose one shade of green from the twelve above to be Green, it would seem to be an entirely arbitrary choice and clearly open to dispute amongst people.

Plato would argue that the source (or Form) of Green cannot be one of the many shades of green we find in the world, but must lie beyond the world (or outside the realm of our immediate sense-perception). This also means that the source (or Form) of Green must be fixed, unchanging and permanent (or what we previously referred to as immutable), for if it were not then it could not act as a standard for the shades of green.

In The Republic 523c-524d, Plato argues that sense-based knowledge requires us to posit the existence of the Forms, in order to make sense of our experience of certain things. Stretching out his hand, he says to Glaucon that although there is no question that he has fingers on his hand, the actual the size of his fingers is more difficult to ascertain.

Plato's discussion as to whether our fingers are large or small, is intended to shake off naive notions about what we might claim to know about ourselves and the world around us. Most people assume that experience provides us with indubitable (unquestionable) knowledge, yet Plato shows that the moment we start to ask the question, 'Is the ring finger big or small?', we are beginning to cast doubt on our senses to give us true knowledge of things. As a result, we will begin to look for other ways to ground what we claim to know of things. It is also at this point that Plato believes people will naturally look for the Form (or ideal) of things.

'It's probably in this sort of case... that the mind calls in reasoning and thought.'

As the Forms are said to be outside the physical realm, they are unable to be directly perceived by the senses (touch, taste, sight etc.). This means we cannot attain knowledge of them using empirical methods. Instead, we perceive them (or come to know them) using our intellect.

For instance, no-one has ever seen the Form of Green, however logically something like this must exist if we are make any sense of the notion shades of green. Plato believed it was when people began to reflect on the nature of things in this way, that they began to look beyond their immediate sense-based perceptions and start to attain knowledge of the Forms. In light of this Plato was particularly keen on the study of Mathematics, as he believed this was the best means to start people considering the more abstract elements of knowledge.