Plato was a duellist and thus believed that there are two worlds; the material world and the world of ideas/Forms. The world of ideas or Forms is the true reality and the world of appearances is just reflections of world of Forms. Plato believed that our knowledge of the Forms was a priori which means that our souls knew the Forms before it was inside us, therefore we have knowledge prior to experiencing the objects with our senses.
Plato believes everyone is born with an intuitive but imperfect understanding of the Forms. He also believes the philosopher is able, through using his intellect, to achieve true knowledge of the abstract Forms without using his senses. Plato’s theory of Forms can be seen as unconvincing to some who believe that abstract ideas e. g table, horse, beauty are actually names that have been invented to help people describe their experiences of the physical world.
This is a materialistic view as it suggests that objects in this world are the real reality and our ideas can develop based on experience of things. Aristotle agrees with this and believes knowledge is gained through experience and that there is not an eternal World of Forms that is a priori to us. However, in Plato’s defence some believe that each variety of a Form shares a likeness for example each horse is slightly different yet they all share something that makes it resemble a horse.
According to Bertrand Russell, Plato`s theory made a `very important advance in philosophy, since it is the first to emphasise the problem of universals’. Plato’s theory is often regarded as unconvincing due to the fact that Plato believes that every object and idea in the world of appearances is an imperfect copy of an image or Form in the World of Forms. This suggests that there is a perfect Form of things such as a cinema ticket, mud or an insect and so on. According to Bertrand Russell, his ideas of the Forms when taken to its extreme.