Thursday, June 13, 2013

Leibniz, Kant and the Principle of Sufficient Reason: Part I

   Leibniz and Kant share a great deal in common, and we can come to appreciate both thinkers more through getting a sense of how their thoughts meet.  One point of Kant's thought opened up when related to Leibniz's concerns the principle of sufficient reason which states that there is nothing without a reason.  I will briefly cast a glance at what seems most different about Kant and Leibniz in relation to this principle, and then describe how it is that these differences are different so that they can once again fall into a relationship of sameness.
   Through the principle of sufficient reason Leibniz understands a demand placed on us to provide grounds for every finite truth.  For example, whatever happens depends on something before, and this gives us an infinite series.  But what is the sufficient reason for the existence of this entire causal series?  The being which stands beyond the series of causes as its ground is God, and, being infinite, God requires no further ground.  We recognize this as the cosmological argument, and may remember that Kant found it to be insufficient.  This insufficiency of the cosmological argument is just one instance where Kant found our reasoning goes astray, but this insufficiency is symptomatic of reason's whole functioning.  This signals a marked difference in the attitude Kant has towards the role of the principle of sufficient reason.
   The very first sentence of the Critique of Pure Reason, which I quote on this blog frequently, reads:
"Human reason has this peculiar fate that in one species of its knowledge it is burdened by questions which, as prescribed by the very nature of reason itself, it is not able to ignore, but which, as transcending all its powers, it is also not able to answer."

These "questions prescribed by the very nature of reason" that transcend reason pertain to what Kant describes as the ideas: soul, World and God.  Among other descriptions, Kant calls reason the faculty of ideas.  As the faculty of ideas, it pursues the unconditioned of the different series of relations.  This is much in the same spirit of Leibniz, as we can easily see that what reason demands of us in the questions it prescribes is the same as the demands of the principle of sufficient reason.  However, for Kant, while a sufficient reason is demanded, human cognition is insufficient to the task - at least in its theoretical employment, that is, when it concerns knowledge of what exists.
   Because Leibniz confidently proceeds with the great principle of sufficient reason to God, and Kant does not, it seems to us that this is a great point of difference between these to great thinkers.    However, we may not understand this difference.  We can align Kant with Leibniz by pointing out that even while Kant says that we cannot attain to a knowledge of the unconditioned, reason still has this idea which pushes us towards such completeness.  For Kant, we do posit God as that which grounds coherence, even if it is merely as an idea.  Further, Kant's denial of our knowing God's existence ultimately amounts to the inability to be given any (empirical) intuition of Him.  Leibniz would also agree that we do not sense God, and so Leibniz would agree that if knowledge of existence requires a possible intuition, then we cannot possibly come into this relation to God.  For Kant, God is part of our nature, for Leibniz, God is something we satisfy ourselves about with a proof.
   Leibniz takes the employment - the use - of the principle of sufficient reason in relation to all the finite world demands that we must assent to the existence of God (I must note again that existence does not mean the same thing here that it means for Kant).  Kant, on the other hand, does not speak of the principle of sufficient reason when discussing the ideas, but it is clear that he sees reason as the operation of that principle - not as a piece of equipment which we employ for use relative to this or that truth, but concerning the demand our own nature puts on us a priori.  While Kant denies that we can know the existence of God, God is still a necessary idea of reason governing the coherence of all knowledge.  This is to say, that Leibniz's argument is not wrong, but it is an argument which need not, perhaps should not, be given: our very nature is already entangled with the form of this argument.  But, what is the problem of giving the argument?
   (Heidegger noted that Kant took the scandal of philosophy to be that no proof of the external world has been given, and, maybe, Heidegger thought he improved Kant by saying that the real scandal is that we tried to prove the external world at all.  Perhaps we can see now that Kant did not need any assistance from Heidegger, though we can appreciate his clarification.)  
   Kant does not argue for God's existence, but rather shows how God is posited by our very nature — by reason.  Everything we argue about – that we speak about – is in conformity with our way of thinking, and so has the character of an object in general.  This means that it depends upon the possible application of the categories - it depends upon the temporal.  If we are to give an argument for God's existence (or the existence of the external world) we begin to treat God under the categories, and bring him implicitly into the scheme of the temporal as if he were another thing among others which would required something to cohere it with all other beings - that is to say, the sort of God we argue for is restricted in advance to require an even higher God (just as Parmenides points out for Socrates the problem of the regress in forms).   I hope to deal with this more completely in another place.
   For Kant, God must remain 'problematic', which is to say, indeterminate whether it is possible or impossible.  God must remain this way at least for theoretical reason, which concerns existence, but as a posit that guides our activity - as a maxim - God has a practical reality for us.  Kant's conception of Practical Reason is another key for coming to understand how this difference between Leibniz and Kant, and perhaps will guide us to see how Leibniz is justified in arguing for the existence of God without the result of him being a member of an even high order series.