The Theory of the Forms is also seen as unconvincing as it is highly abstract. Therefore it is too incomprehensible to see the way in which these detached Forms can be practical or have significance in the real world as they are too distant. Even if they do exist, do they have a practical function? Can they help humans make decisions about practical matters? In addition very few people will obtain knowledge of the good therefore can the Forms realistically be understood and accepted by all? In this way the Theory is not convincing as it leaves many basic questions unanswered.

We are also to question whether there are Forms for everything, from a stone to a lampshade. Plato rarely discusses physical and material objects but more Forms of concepts such as Justice. While he does mention the Form of a bed in The Republic, we are uncertain as to whether this was a serious remark, some even think it was a joke. Furthermore Plato does not clearly explain the link between the World of Forms and that of Appearances, how do they connect? Furthermore we question how general the Forms are. Is there a Form for every breed of horse or just a general Form of a horse? If a Form is a general idea then there is a risk that it lacks detail. However if every breed has a Form then surely the Form loses it's point. One could argue that every breed of horse has enough in common to reflect to some extent the Form of a horse. Again this may not be an issue for Plato if the Theory of Forms applies only to abstract concepts such as goodness.

Surely there are different variations to the concepts that Plato discusses such as Good and Justice. There cannot be an 'overall' good as each action or intent of 'good' varies depending on the person and situation. Goodness is also relative to particular things or circumstances. For example, a knife may be seen as very good if it is used for cutting and is very sharp as it fulfills its purpose. How someone uses a knife to murder someone is not in itself an act of goodness and yet just because the knife was the object that killed the person does not make it bad, in fact it could be good as it successfully killed someone. However this example refers to a physical object not a concept. The concept of love could be used as an example: whether to terminate someone's life as they are in interminable pain would be the modt loving thing to do and yet the act of 'killing' someone doesn't fit under the category of love. Bertrand Russell thought of the concept of universals: the 'idea' justice is not identical with anything just, it is something other than particular things, which they partake of. Not being particular cannot itself exist in the World of Appearences. He also argues that the theory of Forms is convincing as when we use a word of an object, for example a tree, we do not refer to a particular tree but the general idea of a tree.

Aristotle would argue that the Forms are unconvincing from his Third Man Objective. He says that if a particular man is in someway a copy of the Form of a Man, how do we know the Form of a man isn't a copy of something else, a third man perhaps? This could also be a Form of another thing, so how do we know when to stop? Are there an infinite regress of copies or is there an original? Plato would argue that a Form cannot be a copy of something by definition; it is an eternal idea.

Plato believes that anyone who would come to know and understand the Form of the Good, he will act on it as if it has a motivational agent. However humans are not perfect and he does not take into consideration the weakness of will of some people which may corrupt them. This is a naive view of Plato which may undermine the rest of his arguments.

The most persuasive argument against The Theory of the Forms is that there is a lack of evidence for the existence of the Forms which Plato seems to regard as real entities. However Plato does present the story of Meno's slave as evidence. The boy is able to recollect the Forms and is then able to double the area of a square. But Socrates asked the boy questions in which there could have been clues and in a way he was teaching the boy. The example is also a matter of logic, it would have been less plausible with Forms of physical objects. It is also more plausible to suppose that we learn about the world through sense experiences than that we actually remember Forms. The modern scientific approach would also reject the theory as there is no empirical evidence