The theory of Forms or Ideas is at the center of Plato’s philosophy. With this respective theory, one can understand all his other views on knowledge, psychology, ethics, and state.

Plato’s theory of forms responds to the significant metaphysical question of what is actual reality?

Plato posits that the physical world we see is not the ‘real’ world. It is not true reality; instead, it is a less perfect copy or reflection of an ideal world of ‘Forms’, and the objects we see in our physical world can be considered shadows or reflections of the true forms.

The ‘Forms’ are abstract, perfect, unchanging, timeless concepts or ideals that transcend space and time.

Theory of Knowledge

His Theory of Forms or Ideas, taken from the Greek word ‘Edios,’ is so interrelated to his Theory of Knowledge that they can be understood together.

Plato’s theory of ‘Forms’ or ‘Knowledge,’ or ‘Idea’ is found in his work ‘Republic’ when he discusses the image of the divided line and the ‘Myth of the Cave’ or ‘Allegory of the Cave.’ In the former, Plato distinguished between two levels of awareness; ‘Opinion’ and ‘Knowledge.’ Claims or assertions about the physical Or visible world are opinions. On the other hand, the higher level of awareness is knowledge because there ‘reason’ is involved.

Following Socrates, Plato believed that ‘knowledge‘ is attainable and believed it to have two essential characteristics:

  • Knowledge is certain and infallible;
  • It is to be contracted with which is only appearance.

According to Plato, ‘Knowledge’ is fixed, permanent, and unchanging, identified with the realm of ‘ideal’ as opposed to the physical world, which looks as it appears. In other words, ‘Form,’ ‘Idea,’ ‘Knowledge’ – all constitute what is ideal, and what appears to the eye is actual.

There is a difference between what is ideal and what is actual; between what are ‘forms’ and what are appearances; and between what is knowledge and what is an opinion; and between what ‘can be’ and what it is or what it is ‘becoming.’

What is Naive Realism?

Plato is arguing against a very common and scientific worldview. This worldview is called “Naive Realism,” which is the idea that we can perceive objects as they really are and directly perceive their true essence.

A naive realist would claim that our physical world is the real world. Most people take it for granted that naive realism is just a specific paradigm, a way of seeing the world, so we should not blindly accept it as the absolute truth even though we’ve been raised in a society that makes it seem obvious. These obvious ideas are typically the assumptions that must be questioned most, even though they might be against what is commonly believed.

Plato goes against conventional wisdom with his theory of forms. So we must open up to these new ideas and try our best to understand them, so we don’t become too ideological and defensive over the beliefs that we currently have about the world.

What exactly is the real world in Plato’s view?

World of Forms

Plato believes the ‘real’ world is composed of pure forms or essences.

For Examples;

What makes an apple an apple? 

There are many different types of apples, and they can decay and mold, but what makes each of them an apple is the one thing they all have in common is Apple-ness and can be thought of as the form or essence of an apple.

Example #2;

What do all wise men have in common? Or

What makes a wise man wise?

The answer is wisdom. We can think of wisdom as the essence of a wise man. Some more examples of pure forms or essences that reside in the world of forms are those of friendship, love, goodness, and beauty. 

This world of forms contains the perfect ideal of the thing it represents, whereas, in our physical world, we only perceive the shadows of these forms. For example, the true form of beauty resides in the world of forms, but in the physical world, we cannot directly perceive the true essence of beauty. Still, we can recognize its imitation in objects, typically in people, nature, or artwork.

Plato explained that there is a difference between things that are ‘beautiful’ and what ‘beauty’ is; the former lies in the realm of opinion while the latter is in the realm of knowledge. More important is Plato’s insistence that knowledge makes the journey from ‘appearances’ to ‘form’ possible.

It is essential to remember that Plato does not think that the world of forms is a physical place on the other side of the universe that one could walk around; instead, it is a place that completely transcends ideas of space and time.

Plato thinks that these non-physical forms are more real than any physical objects that imitate them because the forms are timeless and unchanging. In contrast, things in our physical world are liable to decay and change, so we’re just shadows of the real forms.

Whether or not we can ever perceive the forms?

With the senses

We cannot interact with the forms directly as they don’t exist in our spatial and temporal physical world. For example, we cannot directly come into contact with apple-ness or goodness; we can only come into contact with the shadows of these forms.

With the mind, reason, and practice

We can perceive the world of forms by recognizing their imitation in the physical object of our world. It is the job of what Plato called the philosopher Kings or guardians.

Must Read- Plato’s Ideal State

The one way we can come to know the forms is through the argument from opposites; one can come to understand good by contrasting it with what is bad.

Plato calls an inner part of us the “soul“, which is eternal and unchanging. Before the body localized the soul, it was connected with the real world of the forms. This is why after the body has confined the soul, we retain a dim recollection of the forms and can come to understand them.

Characteristics of Plato’s Theory of Forms

The essential characteristics of Plato’s theory of Forms would thus, include;

  • (a) There is a difference between ‘Form’ or ‘Idea,’ ‘Knowledge‘ and ‘Appearance,’ ‘Actual,’ or ‘Opininn’ as there is a difference between the ideal/invisible world and the physical/visible world.
  • (b) The Form is the ultimate object of appearance.
  • (c) The actual world can attain the ideal world.
  • (d) Knowledge can replace the opinion and is attainable.
  • (e) The ‘Visible World’ is the shadow of the ‘Real World’ or ‘Intelligible World.’
  • (f) What appears to be is not the Form but is a form of the Form.

The Philosopher King

The task of philosophy and the philosopher Kings is to understand the true forms of ideals such as friendship, goodness, truth, wisdom, virtue, and justice and integrate this knowledge as best they can into the physical world.

Plato’s theory of Form has extended to his political theory. The types of rulers Plato sought to have should be those who have the knowledge of ruling people. Until power is in the hands of those who have knowledge (i.e., the philosophers), states would have peace, so thought Plato.

Closely Linked with the Plato’s Allegory of the Cave

The ‘Allegory of the Cave’ discussed by Plato described a group of individuals chained deep within the recesses of a cave where the vision is restricted, and no one can see another man; the only visible thing is the wall of the cave. Breaking free, one of the individuals escapes from the cave into the light of the day. With the aid of the sun, that person sees for the first time the real world, telling his fellow men that the only things they have seen previously are shadows and appearances and that the real world awaits them if only they are willing to struggle free of their bonds.

Each form is a ‘blueprint‘ of perfection. It is our duty to try to replicate the forms of goodness, wisdom, and justice as best we can, and this is the philosopher King’s purpose to help society do just.

Critiques of Plato’s Theory of Forms

However, criticisms have been made against Plato’s theory of forms. Firstly the question arises;

  • Are undesirables such as evil, corruption, suffering, and disease are allowed into the world of forms?
  • Is there a form, a perfect ideal of evil, suffering, or disease?

Plato would say that undesirables do not reside in the world of forms; “evil” is just a privation or a lack of good.

Finally one of the main arguments cited against Plato’s theory of forms is “Aristotle’s third man argument”;

  1. We know that Plato is a human because he partakes in the form of “human-ness”
  2. But a new form is needed to explain how both the human and the form of “human-ness” are both “human”.
  3. What makes a “super human-ness” a human?
  4. Using the same repeated argument, we could say that “super dooper humaneness” makes it human.
  5. We could repeat this argument ad Infinitum, which is one of the main problems with the theory of forms.


Plato had conceived the Forms as arranged hierarchically—the supreme form is the ‘Form of the Good,’ which, like the sun in the myth or allegory of the cave, illuminates all the other ideas. The Forms of the Good (i.e., the idea of the Good) represent Plato’s movement toward attaining goodness.

In a way, the theory of Forms, as propounded by Plato, is intended to explain how one comes to know, how things have come to be as they are, and how they are likely to attain their ideals.