Plato's Theory of Forms

I. The Problems the theory was meant to solve:

1. The Ethical Problem: How can humans live a fulfilling, happy life in a contingent, changing world where every thing they attach themselves to can be taken away?

2. The Problem of Permanence and Change: How can the world appear to be both permanent and changing? The world we perceive through the senses seems to be always changing. The world that we perceive through the mind, using our concepts, seems to be permanent and unchanging. Which is most real and why does it appear both ways?

The general structure of the solution: Plato splits up existence into two realms: the material realm and the transcendent realm of forms.

Humans have access to the realm of forms through the mind, through reason, given Plato's theory of the subdivisions of the human soul. This gives them access to an unchanging world, invulnerable to the pains and changes of the material world. By detaching ourselves from the material world and our bodies and developing our ability to concern ourselves with the forms, we find a value which is not open to change or disintegration. This solves the first, ethical, problem.

Splitting existence up into two realms also solves the problem of permanence and change. We perceive a different world, with different objects, through our mind than we do through the senses. It is the material world, perceived through the senses, that is changing. It is the realm of forms, perceived through the mind, that is permanent and immutable. It is this world that is more real; the world of change is merely an imperfect image of this world.

II. The Forms:*

A form is an abstract property or quality. Take any property of an object; separate it from that object and consider it by itself, and you are contemplating a form. For example, if you separate the roundness of a basketball from its color, its weight, etc. and consider just roundness by itself, you are thinking of the from of roundness. Plato held that this property existed apart from the basketball, in a different mode of existence than the basketball. The form is not just the idea of roundness you have in your mind. It exists independently of the basketball and independently of whether someone thinks of it. All round objects, not just this basketball, participate or copy this same form of roundness.

In order to see exactly what a form is and how it differs from a material object, we need to look at the first two of the properties that characterize the forms. The forms are transcendent. This means that they do not exist in space and time. A material object, a basketball, exists at a particular place at a particular time. A form, roundness, does not exist at any place or time. The forms exist, or subsist, in a different way. This is especially important because it explains why the forms are unchanging. A form such as roundness will never change; it does not even exist in time. It is the same at all times or places in which it might be instantiated. A form does not exist in space in that it can be instantiated in many places at once and need not be instantiated anywhere in order for the form to exist. The form of roundness can be found in many particular spatial locations, and even if all round objects were destroyed, the property of roundness would still exist.

The forms are also pure. This means that they are pure properties separated from all other properties. A material object, such as a basketball, has many properties: roundness, ballness, orangeness, elasticity, etc. These are all put together to make up this individual basketball. A form is just one of these properties, existing by itself apart from space and time. Roundness is just pure roundness, without any other properties mixed in. The forms differ from material objects, then, in that they are transcendent and pure, while material objects are complex conglomerations of properties located in space and time.

To see how forms are related to material objects, we need to look at the other four properties that characterized the forms. The forms are the archetypes or perfect models for all of the properties that are present in material objects. The forms are the perfect examples of the properties they instantiate. The material world is really similar to the more real world of forms. The form of roundness, for example, is the perfect model of roundness. All round material objects are merely copies or imitations of this most real form. Thus it is the forms that are ultimately real. Material objects are images or copies of these more real objects. The cave metaphor illustrates these properties of the forms well. The shadows on the wall represent material objects, while the real objects passing before the fire are the forms.

In virtue of the fact that all objects in this world are copies of the forms, the forms are the causes of all that exists in this world. In general, whenever you want to explain why something is the way that it is, you point to some properties that the object has. That is, you explain what forms the object is a copy of. The forms are causes in two closely related ways: (1) The forms are the causes of all our knowledge of all objects. The forms contribute all order and intelligibility to objects. Since we can only know something insofar as it has some order or form, the forms are the source of the intelligibility of all material objects. (2) The forms are also the cause of the existence of all objects. Things are only said to exist insofar as they have order or structure or form. Hence, the forms are the causes of the existence of all objects as well as of their intelligibility. Plato uses the sun metaphor to explain how the forms in general, and the form of the Good in particular, are causes in these two ways. Just as the sun gives light which allows us to see objects, the form of the Good provides order and intelligibility to allow us to know objects. Just as the sun provides the energy for the nourishment and growth of all living things, so the form of the Good provides the order and structure which is the source of the existence of all things.

The forms are also systematically interconnected. They are connected to each other and to material objects in an intricate system that reflects both the way they flow down from the form of the good and the process that we must go through in working our way up to knowledge of the forms. The forms fit together with each other and material objects in a hierarchical system, whose structure is reflected in the dialectic process one goes through to gain knowledge of the forms. Dialectic involves putting together two subjective points of view to form a more objective concept. So the forms flow down form of the Good going from most general, abstract, and objective (the Good) to most particular and subjective. All particular forms are subsumed under more general forms, and all forms are finally subsumed under the form of the Good. In dialectic, we work in the opposite direction and start from subjective concepts of the more particular things and work our way towards more objective concepts of the general, abstract forms. The divided line represents the systematic interconnectedness of the forms and how the advance of our knowledge reflects this system. The structure of the relationships between forms and material objects might be represented in a diagram such as this, which is merely an expanded version of the divided line set on its end:

The six main properties of the forms are summarized below:

Properties of the Forms

The forms are:

1. Transcendent - the forms are not located in space and time. For example, there is no particular place or time at which redness exists.

2. Pure - the forms only exemplify one property. Material objects are impure; they combine a number of properties such as blackness, circularity, and hardness into one object. A form, such as circularity, only exemplifies one property.

3. Archetypes - The forms are archetypes; that is, they are perfect examples of the property that they exemplify. The forms are the perfect models upon which all material objects are based. The form of redness, for example, is red, and all red objects are simply imperfect, impure copies of this perfect form of redness.

4. Ultimately Real - The forms are the ultimately real entities, not material objects. All material objects are copies or images of some collection of forms; their reality comes only from the forms.

5. Causes - The forms are the causes of all things. (1) They provide the explanation of why any thing is the way it is, and (2) they are the source or origin of the being of all things.

6. Systematically Interconnected - The forms comprise a system leading down from the form of the Good moving from more general to more particular, from more objective to more subjective. This systematic structure is reflected in the structure of the dialectic process by which we come to knowledge of the forms.

III: Plato's Arguments for the Theory of Forms

A. The general argument from objectivity:

The general structure of Plato's argument is as follows:

1. We already believe that the more objective a concept is, the more real the thing it represents. We show that we believe this by the way we use objectivity to distinguish appearance and reality. This is a version of what we will call Plato's principle: The more objective you get, the more real you get.)

2. The forms are more objective than material objects.


Therefore, the forms are more real than material objects.

Plato's argument for premise 1: The world that we perceive with the senses often deceives us. This would not be so if the world and objects that we perceive with the senses were the real objects.

It seems that all the objects we perceive with the senses are simply images or experiences in our mind. They are only subjective points of views on the real objects. For example, the world appears radically differently to a color blind person than it does to us. The objects that we perceive as colored, then, must not be the real objects, but just our experience of these objects that is determined by my particular subjective point of view and perceptual apparatus.

Once one sees that the world that we perceive through the senses is not the real world but just an image of it, it becomes difficult to determine at what level of description we get in touch with the real objects that make up the world.

In general, we assume that the more objective the concept or description, the more real the object it describes is. For example, when we see a person far away, we automatically follow our objective concept of humans as being about 6 feet tall and see the person as normal sized, even though the subjective image we have is of a very tiny person. In general, we form a more objective concept by combining different points of view into a more objective description that takes into account what all the other views had in common. This process is called dialectic: the back and forth discourse between different points of view that leads to their combination or synthesis into a more objective conception that takes into account both points of view.

Plato's argument for the second premise: What then are the real objects? They cannot be the subjective images we perceive. These often deceive us.

What about the everyday material objects, like chairs, tables, rocks, and trees, that we think our subjective perceptions of things refer to? The concepts we from of these are slightly more objective than subjective images. They combine and take into account all of the subjective images we can form of a single object, such as this particular asterisk * . Yet, there are reasons to avoid taking this as the real object as well:

1. We only contact these objects through subjective images. We never perceive them directly.

2. These objects contain a number of properties that are mixed together. Any description of the object that doesn't separate out these properties cannot explain what makes the object act the way it does. For example, If all you know about the asterisk above is that it is the particular thing it is, you will not know as much as if you know that it is black, star-shaped, made of ink on paper, etc.

3. These objects are always changing, taking up different properties from moment to moment, and going in and out of existence.

For these reasons, it seems that the only level at which things really exist must be the level of single properties separated from particular objects. These are the forms:

1. Our concepts of these are more objective than our perceptions of material objects. For example, my concept of blackness takes into account all the points of view anyone can have on any black object, while my perception of the asterisk above only takes into account those views you can have of this object. The object that my concept refers to, the form, must be more real than a material object.

2. The forms explain why an object is the way it is. It is the fact that an object has the properties that it does that makes it what it is, not that it is the particular thing it is.

3. The forms never change.

B. The argument from mathematics:

The most certain knowledge we have, the knowledge of mathematics, could not have come from sense perception:

1. In geometry we have access to perfect squares and circles, but no such objects exist in the material world.

2. We can know truths such as 2+2=4 without having to check our experience of the material world.

The objects that we think about in mathematics must be real, since they are most certain. Since they could not exist in the material world, there must be another realm in which they exist that is even more real, the realm of forms.

C. The argument from relativism:

All we ever perceive of the world are subjective perspectives. Unless there are forms it seems that some form of relativism is true. Relativism is the view that all that exist are subjective points of view about such things as truth, beauty, and justice.

Plato held that relativism must be false for a number of reasons:

1. Relativism is self-defeating. If relativism is the view that there is no truth, then is relativism true?

2. We do often objectively discuss and argue about concepts like beauty and truth and justice, and by this dialectic process we come to a better understanding of them.

If there are forms of beauty, truth, and justice then it is possible to objectively criticize subjective points of view about these things.

IV. Plato's Argument that Only Objective Value is Real:

A. The argument from objectivity:

Plato's argument with respect to value has the same form as his argument for the reality of the forms:

1. We already believe that the more objective a value is, the more real it is. This is shown by the way we distinguish real values from apparent ones.

2. Only detachment from all particular desires for objects and persons can be completely objective.


Therefore, only detachment from all particular objects and persons has real value.

Plato's argument for premise 1: We all realize that something that only makes us feel good for a moment, but which leads to pain in the future isn't a real value. We determine what things are most valuable by seeing what values last the longest or are valued from the most points of view.

Plato's argument for premise 2: As long as we are attached to particular things and people we will always be open to pain; there will always be some point of view from which the value will disappear.

B. The Argument from Analogy to Itches and Hunger:

1. All subjective values are like itches and hunger.

2. The pleasure we get from scratching an itch or from eating arises from a defect or deficiency in us. Once we fill the defect we will feel good, but the defect will inevitably arise again and give rise to dissatisfaction. We will itch again; we will be hungry again. We would rather never itch or never be hungry, than always be scratching and eating.


Therefore, all subjective values are defective in this way. We ought to eliminate all desires rather than trying to satisfy them.


* I am indebted to Donald Watts for this accounting of the essential properties of the forms.

© 2006 David Banach 

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