There is an argument by Kurt Gödel that I find fascinating. Gödel argued that his predecessors’ attempt to create a complete set of logical axioms to ground mathematics was doomed to fail. Instead, mathematical ideas must subsist unto themselves (as must, presumably, logical ideas). Ideas cannot complete each other. They are sufficient unto themselves. But what grounds ideas?
For Bishop George Berkeley, our concrete ideas of the physical realm are sufficient unto themselves, and don’t need ‘objects’ separate from ideas. Indeed, the ideas are what we commonly call ‘objects’, which are nothing more than ideas. But when an object is not perceived by any thinking subject, by which mind does an object exist? For if objects are ideas, only an active perceiving intelligence can sustain their existence in perpetuity. Berkeley hypothesises that a divine intelligence, that of God, can sustain the existence of ideas into the future. When we look away from an object, it still exists as an idea — but not in our mind; rather, in the mind of all minds — the mind of God.
But minds do not only perceive concrete ideas or physical objects. They also perceive abstract ideas or objects of conceptual contemplation. Gödel is a mathematical Platonist. He agrees with Plato that abstract ideas exist in themselves, like physical objects do. He argues that they exist independently of our perception. We could extend Berkeley’s argument that ideas exist in the mind of God. But what grounds God’s ideas? If concrete ideas are below God, abstract ideas are more appropriate to the divine intelligence, of which philosophical contemplation is a bare imitation. The ground for abstract ideas is the moral ideal which God must bow down to: the ideal or Form of the Good. The ground for all ideas is itself a form of an idea; the idea of the Good, on which all other ideas are founded.
If God serves as the ground for our concrete ideas (à la Berkeley) and the Good serves as the ground for our abstract ideas (à la Plato), then our ideas do have a ground beyond themselves. For Spinoza, God and Nature are interchangeable; hence his phrase Deus sive Natura — God or Nature. For Plato, Form culminates in the Good. These are two sides of reality; one is abstract, the other is concrete. But both are ideal, and real. They consist in thought, and are grounded in the objective reality of God and Goodness. Thus, as Heidegger is sometimes taken to have argued, thought and reality are not separate; idealism and materialism are two sides of the same coin. The coin is reality, of which the ideal theory is realism. Sometimes, as Wittgenstein argued, it is hard to bridge this gap, and language serves as a partial bridge in the games of life — but these games might culminate in the truth of philosophy and the light of reality. In this way, the philosophy of pure ideas is itself a path towards a practical politics of divine presence and human grace. Shall we begin?