The statement that claims to have knowledge of a world beyond sense experience are doomed to fail is a strict empiricist position. In order to assess this I will begin by establishing the empiricist position and then consider criticisms of this, including Plato’s theory of the Forms.
The strict empiricist thesis argues all substantive knowledge is gained a posteriori, through our experience. In Hume’s conception our ideas are copies of sense impressions, for example we may feel a cold sensation from snow and this imparts on us the idea of cold in the form of a copy of the original sense impression. Hume did concede there were analytic truths but argued these were hollow for they tell us nothing new, they provide no synthetic knowledge about the nature of reality. This is because the truth of an analytic claim is already contained within the definition so, strictly, we discover nothing new.
Plato’s position was in stark contrast to this and would nowadays be considered a rationalist thesis; that is he emphasised the importance of reason. In his allegory of the cave Plato argued that the world of sense experience is illusory. In the allegory we are asked to imagine a line of prisoners chained to face a wall. Behind them there is a fire and objects beyond the cave cast shadows onto the wall. The prisoners only ever see shadows of the true object. Here our sense experience is represented by the shadows. To appreciate the true nature of reality, Plato argues we must leave the cave or the sensible world and look upon the objects beyond the cave, or the Forms as Plato would have it. In Plato’s thesis the Forms are objects expressing their essence perfectly. If we consider beauty, there are many beautiful things we see but never beauty itself. Plato claims there is a Form of beauty which these particular things participate in to derive their beauty. The Forms are self predicating meaning the Form of beauty is itself beautiful.
Plato argues that we can have knowledge of the Forms because we can have certainty about them; they are unchanging, perfect objects. We do not come to know them through experience, rather we gain knowledge of the Forms though mathematical and dialectic reasoning. Overarching the whole of Plato’s theory is the Form of the Good. This may be understood as the Form of the Forms and, as espoused in the simile of the Sun, gives the light through which we may acquire knowledge of the Forms. Through all this Plato would argue we can only have knowledge of a world beyond sense experience for it is only this world that provides the unchanging certainty required by Plato.
We may consider now the coherency of the idea of the Forms. In Aristotle’s third man argument we may consider a group of small things, A, B and C. These all share the property of smallness so there must be a Form of smallness, U. However the Form of smallness, U is also small. Thus there is a new totality of small things, A, B, C and U. Again, these are all small so there must be another Form, Z and so on ad infinatum. This reductio ad absurdum clearly demonstrates that in pushing Plato’s theory of the Forms to its logical conclusion we are led to absurdity and thus recognise the initial premises to be logically fallacious. This argument may be made even more powerful by pointing out Plato’s own argument fails by the very dialectic he so admires.
While the theory of the Forms is logically incoherent we may consider another claim made by Plato in the simile of the divided line. In the knowledge category Plato placed mathematical reasoning alongside his higher category of noesis which involved knowledge of the Forms. While the Forms are logically flawed as an idea due to the generation of an infinite regress there may still be a possibility that mathematical truths give synthetic a priori knowledge. While Hume would argue mathematical truths are analytic this seems to be an unfair assertion. If we consider the move from flat Euclidean geometry to Riemannian geometry, this is not just a matter of definitions. Rather we learn something about the nature of space, namely that it is curved, and so realise that substantive knowledge can be gained beyond the sensible world.
In conclusion, having established the strict empiricist position we were able to consider Plato’s theory of the Forms. By Plato’s reckoning we could have knowledge of the Forms due to their perfect and unchanging nature. The sensible world on the other hand was viewed as being in an illusory state of flux. However, by Aristotle’s third man argument the idea of the Forms was shown to be logically absurd and so we rejected the idea. Mathematical truths were then considered and it was realised they could provide substantive knowledge and so the initial empiricist claim was refuted by counter example. Thus we must conclude the statement that claims to have knowledge of a world beyond sense experience are doomed to fail is false.
