Logic and Existence: Deleuze on the Conditions of the Real

Here is a philosophical problem that lies at the core of Deleuze's interest in the rationalists, and particularly Leibniz.By itself, thought has no means of distinguishing between the possible and the real. I can have a concept of 100 dollars in my mind, and while it may be important to me practically whether or not I actually have 100 dollars in my pocket, the existence of 100 dollars in reality changes nothing from the point of view of the concept: that is, from the viewpoint of pure thought. The position of the real is outside the concept ; the existing thing is external to the concept. (This was Kant's argument against the ontological argument: existence is not a predicate ; from the viewpoint of the concept, an existing God is no more perfect than a non-existing God.) Even though I know that unicorns do not exist, I can still form a concept or a representation of a unicorn, or define the essence of a unicorn.

For Deleuze, this is one of the fundamental problems of a theory of thought: How can thought leave this meager sphere of the possible in order to think the real: that is, to think existence itself, to think existing things. Pre-Kantians like Leibniz approached this problem in terms of the distinction between truths of essence ("A triangle has three sides") and truths of existence ("Caesar crossed the Rubicon"), while post-Kantians like Maimon approached the problem in terms of the distinction between the conditions of possible experience and the conditions of real experience. I would like to approach this logical problem from a semi-cinematic perspective. "Theoretically," Deleuze once mused, "Jean-Luc Godard would be capable of filming Kant's Critique or Spinoza's Ethics " (DI 141).