Epistemology

This section will not focus on the problems raised by Descartes and Hume, concerning whether knowledge is possible. Leibniz believed the world intelligible and ultimately knowable, the problems raised by the skeptic Hume coming after him. He has some words to say to Descartes, who came before Leibniz, concerning whether the world is knowable; but proving that knowledge of the external world is possible misses the thrust of his philosophy. He focused so much on what he believed must be true that stripped-down ideas that leave no point unquestioned, to ultimately prove knowledge impossible, or justify it only after the most extreme doubt possible, were not what he was concerned with. This section rather will focus on Leibniz's rationalism—his idea that our main apparatus for discovering and understanding the nature of the world comes from pure reason, and not through the senses.

First of all, Leibniz believed it may have turned out that we did not know necessary truths such as "All green things are green." How is it that I know this proposition holds, even in some galaxy other than ours, on the other side of the universe? It was akin to a divine sort of magic to Leibniz that we should know any proposition that holds true under all circumstances and locations. He called it "an inborn light within us", which lets us cross the wide cosmos in one stroke of thought, and know beyond all doubt that all green things have always been green, no matter where on the earth or in the heavens, from the beginning of time to the end of the cosmos.

So let us examine just how we know that all green things are green. We know it because we know if a green thing is not green, it was an error to call it a green thing in the subject, and it is not in fact green. On the other hand we know that if a thing is green, it is green. Ultimately to deny the proposition would involve us in a contradiction. So we know either that it is true, or that there are such things as true contradictions. But we know there are no such things as true contradictions: and so we know that all green things are green.

So the question boils down to this: how do we know there are no true contradictions? We cannot prove this is true without assuming its truth in the first place, for any demonstration of any proposition is valid only if there are no true contradictions—the very thing we are trying to prove. And so were we to avoid begging the question we cannot reason at all. That there are no true contradictions, then, cannot be demonstrated; any demonstration, merely by virtue of it being rational discourse, must assume there are no true contradictions to begin with; and so no demonstration can properly establish this very thing without assuming it as a premise and prerequisite.

How, then, do we know there are no true contradictions? That is, would we know it if it were merely a quirk of our minds that we cannot comprehend a true contradiction, some arbitrary way our brains developed, that has nothing to do with objective reality? Could it be that we simply cannot conceive of a true contradiction in the way that our bodies cannot be sustained by eating stones? Is it merely an arbitrary aspect of the human organism that we cannot conceive of a true contradiction, rather than this being due to the nature of the world itself?

Certainly we would never know this if it were so. We would go on reasoning and making rules of deductive logic that have nothing to do with what is true and false in nature itself, and only reflect arbitrary quirks of our psychological biology, so to speak, and what it can and cannot process as an organism that thinks.

But most philosophers do not think there is much fruit to be had in thinking like this. To question the rule of non-contradiction, or to deny its truth, rests upon assuming its truth as much as asserting its truth does. Aristotle solved the problem by saying if a man doubts that there are no true contradictions, if he speaks and reasons, he is assuming the principle's truth; so if he questions it let him remain silent, but if he speaks and argues he must assume there are no true contradictions to do so, and thus undermines his doubt of the principle. To put it another way: we have no choice but to assume there are no true contradictions if we are to philosophize at all; for whether we use reason to deny the rule of non-contradiction or to assert its truth we are all asserting its truth as a prerequisite. This very discussion of the problem assumes the rule's truth, and so where I question its validity here, ironically, I assert its veracity, by the mere fact that I am using reason.

So let us do what we must, and assume that it is commentary on the nature of things in-themselves that we have the rule of non-contradiction. How, then, do we know its truth? We cannot explain how we know it, only that we cannot conceive otherwise. This is the "inborn light within us" that allows us to cross time and space and know the nature of the other side of the cosmos, which Leibniz found so fascinating. Assuming the rule of non-contradiction is commentary on the true nature of things, it is certainly astounding that we should find a single principle that should apply to all places, times, dimensions and modes of being, from mere act of thought. Certainly were the empiricists correct, they would have a very difficult time explaining just how this "inborn light" is possible. To say we so evolved such that we became rational puts our lack of ability to conceive of a true contradiction back into the realm of an arbitrary biological quirk. It puts it into the chain of causality such that it is the result of arbitrary physical forces, not, after all, commentary on nature in-itself. To do so would be to question the objective veracity of the principle; perhaps we just were able to survive and leave more offspring if we believed there were no true contradictions, though it is not in fact true that there are none. Certainly to call it a result of evolution is to deny the very veracity of the principle, something impossible in philosophy if it is to be philosophy in the first place. Evolution works by preserving the ones who leave the most offspring, not preserving the ones who know the most truth.

Before Kant, philosophy basically had two categories of knowledge: those propositions we know whose contrary implies a contradiction in terms, and those whose contrary didn't. "This apple is yellow" doesn't have a contrary that implies a contradiction, while "All apples are apples" does. Leibniz naturally found it more incredible that we could know the latter rather than the former; the former has no bearing on anything but that particular apple; it does not signify anything beyond the particular circumstance it describes. "All apples are apples," however, holds true from the foundation of the cosmos to its end, in every time and place there is. This was substantive knowledge to Leibniz; and according to Leibniz it is the principles found in such universal knowledge that allowed us to make use of the senses, rather than the senses being the source of our knowledge. Without pure reason, to Leibniz, sense experience would be worthless; we could never progress in knowledge without the eternal principles of analytic reason, with which we analyze and process this sensory data. The senses are subject to doubt as well; they may all be dreams and fictions, while whether I am dreaming or awake, should I think to myself "All apples are apples" the proposition yet holds true, and I know it to be so, whether it occurs to me as I am dreaming, awake or whenever.

Sometimes a philosopher like Hume will propound a skepticism that makes us doubt whether we can even know what the philosopher himself is arguing, if he is right and we really know so little. But equally, empiricists like Hume betray the veracity of rationalism: Hume, after all, did not show us movies to teach us; he wrote books. If pure reason is so worthless, and matters of sense our only avenue of understanding, how is it that we are to learn by merely following Hume's path of reason? Wouldn't he do better to show us pictures and images? After all, all reasoning, Hume's reasoning even, comes in logical form, comes in words and not images, the stuff of thought. Hume's very enterprise of reasoning his way into showing reason worthless itself betrays the value of reason. Never mind that it was mostly inductive reason; if logic and pure reason were worthless, wherefore does Hume write, filling hundreds of pages of logical process? We might say to him that he has an awful lot to say about what must be true, for someone who believes we cannot know the truth. And in addition, he employs logic and reason quite extensively, for someone who believes pure reason can give us no substantive truth.

Leibniz saw quite correctly that, though sense experience is probably essential to human nature, and necessary for us to mature our minds in the first place, it is reason that gives us the perspective and principles to make use of such sense experience. If I should know that a particular apple is green, and a thousand other data of daily sights and sounds, without logic, reason and mathematics, by which I process and analyze and organize such data, none of our sciences would be possible; least of all philosophy, but the physical sciences of nature also. Sense data contains the raw facts of the world; but knowledge comes about when the principles found in the universal rules of reason are used to process such facts into knowing what we do not perceive, be they things like the center of the Earth or the nature of the infant cosmos. Without universal principles, be they creative inductions like scientific theories, or the deductive rules of logic, sense data would get us nowhere—add fact to fact all one's life, without rational analysis, without using the tools of the "inborn light within us", and knowledge would be impossible. I am not so much arguing that were there no sense data there would be in fact knowledge, but only that both are required, that reason works through sense data and sense data bear fruit by means of reason, in a two-way process, both sides of which are to some degree essential.

Angelhaunt.net: Because earth's madness is heaven's sense.