In my previous piece on Plato’s theory of forms, I asked the question – how do we know a table is a table? As Plato’s most famous student, it is no surprise that Aristotle too had an opinion on Forms. What may surprise those new to Aristotle is that he rejected his teacher’s position.

Aristotle’s theory of forms centers on forms being intrinsically linked to objects. They have a substantial form which is unchangeable and an accidental form which changes. Furthermore, he believed forms to be inpermanent and subject to change, growth, decay, and extinction. 

This article is going to focus on how Aristotle rejected Plato and developed his own ideas. Aristotle’s theory of forms is grounded in the senses and in empirical research, but has its own contradictions and issues. In my opinion, the man dubbed ‘The Philosopher’ by Thomas Aquinas, is on the right path but doesn’t quite get there. 

How did Plato and Aristotle differ in their approach?

Society is made up of a complex combination of people with their own complex compilation of characteristics, ways of thinking, and feelings. One thing I saw as a child was how many children, when teenagers, rebel against their parents. Some want to break things, some create, and some conserve – how the world is at the point these people mature determines what they are breaking, creating, or conserving.

Aristotle was Plato’s student and therefore faced a dilemma in terms of how he reacted to his teacher’s ideas. Did he let himself be enthralled by them? Did he conserve them unchanged and unchallenged? 

No, Aristotle’s character seems to have been not only one of deep thought, but of enquiry. He tried to work out how the world worked in all aspects. This meant taking an empirical approach to Plato’s ideas and when doing so, he felt he could not accept his teacher’s ideas.  

How did Aristotle reject Plato’s theory of forms?

Let’s summarize Plato’s theory quickly: Plato’s theory of forms can be summed up as forms being an idealised version of concepts and types. This ideal cannot be defined or replicated by us, but it is inculcated inside us prior to birth so that when we see a table we recognize it from its ideal form.

Aristotle’s rejection of Plato’s theory of forms centers on the relationship between form and object. He also felt Plato’s theory could not adequately explain three notions. These notions were as follows:

  • Forms cannot explain changes or the extinction of things.
  • Forms do not explain knowledge of things.
  • Forms do not explain the existence of a thing.

Let’s take each one separately before going on to look at the relationship between form and objects in the next section.

One: Aristotle observed objects and things changing in time and decaying. This might be rotting wood or rusting iron, or decaying organic matter. Plato’s idealistic theory has form as a permanant abstract which could not answer the change question.

Two: If form and object are separate, and we do not know the universal or idealised form of an object, how do we gather knowledge or what forms are. Furthermore, how do we explain ignorance of a form we’ve not yet encountered or not knowing what something is when we do encounter it?

Three: Plato’s forms are outside of time and space, but how do they exist? Who created them and when? Are universal concepts separate to a divine being? There’s no explanation of how a form comes into being.

Aristotle was not content to just disagree with Plato or to offer questions, but sought to find his own solutions to these problems. He sought to resolve the nature of forms – he agreed in principle that forms existed, where they came from, and their fundamental nature.

Aristotle on the nature of forms and objects

Aristotle’s theory of forms is centred on the idea of Form being within an object. This is a rejection, as seen above, of the idea of form and object being separate. So for Plato, a chair was a chair based on the ideal of a chair, but beauty was separate to the chair, even if it was a beautiful chair. 

This notion was rejected by Aristotle who felt beauty was intrinsic to an object. This did lead to a contradiction within Aristotle’s ideas when it came to art and the intentions of an artist which I’ll discuss below.

The contradictions within Aristotle’s theory of forms

Beauty and the artist

As mentioned above, Aristotle is said to have contradicted himself on the intrinsic link between beauty and an object when looked at via the artist’s inspiration. He believed the artist, when creating art, was reaching for the ideal Form, a universal form, of that object be it a statue, a building, or a vase.

The should not be an assumption that all artists reach for the ideal or universal. Modern British art is the greatest example that artists and architects can reach for the lowest, most crude, and ugly forms while still calling it art. It is not a universal that the artist looks to the ideal form of beauty – or we’ve lost the meaning of the term ‘artist.’

So, to the contradiction, can an object be both beautiful and an attempt by its creator to reach for the universal form of that object? 

Yes, of course. This is not just because beauty is subjective, but because even if it does not reach the artist’s ideal or a universal beauty, it can still be beautiful in itself.

Aristotle and the nature of substance (matter)

The deep root of this apparent contradiction is the nature of substance. This relates to how matter merges into form. First we need to define what Aristotle meant by ‘matter.’ He defines it in 4 senses which are as follows:

  1. Structure of change, including growth and decay (material cause).
  2. Potential to develop into reality (efficient cause).
  3. Stuff without specific qualities (formal cause).
  4. Able to take on form (Final cause).

What Aristotle was trying to solve here is the problem of potentiality versus actuality. That is what something is versus what it could be. This dominates the rest of Aristotle’s theory of forms which I’ll try to lay out, in my own way, below.

To quickly reconsider the 4 senses of matter, let’s look at them in another way (though bear in mind they do overlap):

  • What is the object made of.
  • How the object is created.
  • Expression of what the object is.
  • What the object finally becomes.

The material cause will determine to a certain extent the efficient cause. The efficient cause may determine the formal cause. While the final cause may be the same as the formal cause, it may arise out of it rather than drive it. The formal cause could determine the efficient and material causes or vice versa. It depends on whether the function is derived from the material or the material chosen to meet the function/method.

Nomalistic and realism approaches to substance

These four definitions of matter led to Aristotle making two points in two different publications about the nature of substance and therefore forms:

  1. (Categories): substance is a concept applied to things.
  2. (Metaphysics): substance is real in itself.

The former is the nomalistic definition and the latter is a realism definition. Which one is correct or can both exist in apparent contradiction? I would venture, as Aristotle seems to too, that both can exist. That is to say substance is real in itself, but humans are able to apply concepts to things creating more substance or alternative substance. 

An example on Aristotle’s approach to substance

Across the UK many restaurants and cafes have taken to hipster tendencies. This includes novel vessels for holding the food you’re supposed to eat. Sometimes this takes the form of drinks in glass milk bottles or food delivered on pieces of slate, but for this example let’s think of wood.

One restaurant delivered its burger and fries with a coleslaw side on what appeared to be a wooden chopping board. It was a small paddle-board with a handle and clear cut marks. Empirically I could say it was created with the idea of a chopping board in mind. If I were to go further, I’d say it would be used to cut hard cheeses.

Yet here I was looking at said chopping block acting as a plate. There are wooden plates of all shapes and sizes, but this had the form of a chopping block rather than a plate.

Let’s apply Aristotle’s two ideas:

  • We say the object is a chopping board or a plate because we apply that substance to the object.
  • The object is always itself – a board of wood.

The object is always itself though as Aristotle will note, and as we saw above with the changeability of forms – the board was once a tree. The tree was cut and decayed, but this part was fashioned into a new or changed form. It is still itself even if it is diminised.

From where we applied substance to it by definining it as a chopping board. This function or substance was then altered – the wood did not change, but it could take on a new form by being used as a kind of trendy plate. 

I’d posit that the idea of the contradiction comes from assuming the form of the object was being a chopping block. Metaphysically it is a piece of wood (its substantial form). Being a chopping block or a plate is a categorization of the object not a metaphysical change (also known as its accidental form). Therefore, I suggest there is no contradiction.

Where a contradiction might exist, however, is if the application of substance could contradict its metaphysical nature/substantial form. For example, what if we tried to apply the substance of marble to the wooden board? Here it does not work because while its functional category can change, you cannot wish wood into marble.

Aristotle’s forms were not permanent

Let’s continue with the chopping board-cum-plate. It started life as a seed then became a sappling and later a tree. The tree was cut down and turned into various things. One of these objects was a chopping block, but instead of being used to chop food, it was used to serve food in a hipster cafe/restaurant. 

Throughout this the substantial form of the object remains the same – it’s wood. It grows and develops, dies and is shaped. The accidental substance of the object changes when it is chopped up and carved by man. From here it’s new form can be used in a variety of manners. Perhaps some staff member picked it up by the handle and used it to bat a tomato across the kitchen – another change in accidental form.

Let’s quickly summarise using the 4 senses of matter:

  1. It’s made of wood (material cause).
  2. The wood was cut and carved into shape (efficient cause).
  3. It was expressed as a chopping board (formal cause).
  4. It’s ultimate form is as a hipster plate (Final cause).

To Aristotle, forms did not just change. They also decayed. It is possible that I as a soul may endure into eternity, and I certainly hope so, but I cannot prove it. My physical form is changing as I reach 40 I know it’ll begin to decay. When I die it will be gone within a few hundred years depending on the soil and if I’m cremated. 

Morbid stuff, right? For Plato, forms were eternal and abstract, but to Aristotle they were real and that meant they were not eternal. Individual forms and objects can die and can be forgotten. This is a fascinating difference because it relates to concepts as well as objects. To Plato all concepts have always existed and always will, but to Aristotle, a concept could die too and be lost or it could change.

Aristotle and knowledge gathering (epistemology)

As with Plato, we need to look at where our knowledge of what a table is comes from. Plato believed, as stated above and in my article on Plato’s theory of forms, that some kind of divine being imparted knowledge of the universal or idealized form of an object to our immortal souls before we were granted life. 

This way, on meeeting said object, we could compare it to the idealized form and instantly know what it was – a table. We achieved this while being unable to describe or replicate the idealized form ourselves. The form just existed within us, somehow.

The separate nature of form and object did not make sense to Aristotle. Plato thought in terms of logic, but was not empirical. He did not think using his senses. To Aristotle, the above separateness of form and object meant that a third force must link the two together or there would be no link at all.

Therefore, if he could use his senses to determine a table was a table, then form and object must have a link. This required observation – touch, sight, hearing, taste, and so on. It meant taking into account observable reality in as objective a way as possible.

This means that our understanding of what constitutes a table, is built on observation and learning. We are told something is a table and something similar is also a table, from that we begin to observe objects (substantial form) and uses (accidental form) then tie the two together to discern tables from trays or tables from chairs. In this the knowledge is built from the base up and not 

Aristotle and the form of the soul

What about us and our possible souls? Are we eternal platonist souls plucked from the stars and born or are we Aristotlean in nature? The latter would mean we are conceived and our souls grow as we grow.

Aristotle wrote about the human soul in his work De Anima where he links the soul to the body. This reflects his theory of forms – form vs object. The form is the soul and the object is the body. One cannot be plucked and put in the other, but must be intrinsically linked from the getgo. 

This led Aristotle to the conclusion that the accidental substance of the human soul must be blank like a page without writing (or in his case a blank slate), and that we learn from scratch. To him all learning was a combination of Machiavelli’s three types of learning – empirical, indoctrination, and ignorance. 

Tabula Rasa: The fully formed soul vs. the Blank Slate

As a small aside, Plato’s notion of an inculcated Theory of Forms within each soul formed part of a medieval and later discussion of the blank slate theory. Aristotle put forward the idea of De Anima, which later became Tabula Rasa when resurrected by Thomas Aquinas. In this sense, Plato is arguing against the blank slate idea and proposes a fully formed set of divine notions and ideals instead.

This goes back to the study of epistemology – how we gain knowledge, and is a key distinction between Plato and Aristotle. Knowing what we do about their world views and ideas on epistemology it is easy to see how we ended up with these equally incorrect notions.

The Fully Formed Soul: Plato posits the idea that God inculcates the Theory of Forms within all souls within the Realm of Forms, therefore every baby is fully programmed with these ideals and ideas from birth, so a tabula rasa is impossible.

The Blank Slate: All knowledge comes from the senses. It is therefore empirical and experience based. Notions can change as more data is gathered. Therefore we are blank until we start taking in information.

We should not sit within a battle of the two as both are wrong. Overall, Aristotle seems to be correct in terms of knowledge gathering, but at the same time we are not blank slates. Far from it. 

Plato is right about some ingrained knowledge or systems of knowledge acquisition, but we’re not divinely programmed souls either – there’s no evidence for it.

Steven Pinker in The Blank Slate debunks Aristotle’s notion the best. In short, we are biological programs (genes etc..) which respond to environmental stimuli, and then build on those through the Aristotelian processes of knowledge acquisition. 

I’d just add that we are prone, however, to Machiavelli’s 2nd order of intellect – learning through inculcation. The difference between this and Plato’s forms is that it happens within an unquestioning mind during life rather than before.

How does De Anima affect Aristotle’s theory of forms?

It is important to tie together Aristotle’s ideas. His notion of the soul being connected to the mortal body is in line with his idea of the concept or substance of a form being connected to the object. 

However, his notion of the blank slate is interesting too. If the substantial form is immutable and set – the body or the tree or the marble, then the accidental form is blank at creation. This is fascinating because it allows for functions, notions of beauty, and so on to be allocated to the object.

The central question will be, in terms of categorisation and consideration, what characteristics of a form are substantial and therefore set, and which ones are accidental, and can therefore be changed? An opinion can always be changed and can vary from one beholder to another, while characteristics are harder to change – as noted above, you can’t change wood into marble.

This also shows how Aristotle took a different approach to the notion of beauty within an object as compared to Plato. If Plato is correct, then we all have the same universal or idealised notion of beauty or of a form imprinted within us, and therefore theoretically we all agree on how an objects compares to that abstract notion. 

Yet according to Aristotle we do not. The connection is intrinsic to the object, but there is no idealised universal. Mankind instead looks to that universal and tries to find it. Perhaps this is how an artist reaches for it when trying to create beauty. 


I hope I’ve put together Aristotle’s theory of forms well for you and that it is accurate as well as makes sense. It seems to me that Aristotles theories can be summed up in a few neat sentences:

  1. Forms and objects are intrinsically linked.
  2. Substantial form is unchangeable in nature, but accidental forms can be assigned to a substantial form to modify its function.
  3. Beauty of a form can be idealized by an artist seeking a universal form even if the universal form does not exist.
  4. Substance can be formed through the material, how the material is shaped, the purpose it is shaped for, and how it is ultimately used/viewed.
  5. Forms can change, they can grow and they can wither.
  6. Forms are not eternal, they can die.
  7. Accidental forms are blank slates waiting to be filled in by the beholder.
  8. The study of forms should take an empirical approach based on the senses and on experiences rather than wrestling with thought/logic alone.
  9. We are not imbued with a sense of the ultimate form of an object prior to birth, but learn along the way.

Many of these ideas seem fine to me and are improvements on the Platonist model. Plato seems too abstract and too idealistic. It’s easy to see how his views lead to mindless utopianism and indoctrination whereas Aristotle is linked to empirical research and realism. That is not to say Aristotle is perfect.

What do you think about Aristotles theory of forms?