Montaigne writes of the manners of the ancient skeptic Pyrrho:
Pyrrho, he who erected so pleasant a knowledge upon ignorance, endeavoured, as all the rest who were really philosophers did, to make his life correspond with his doctrine. And because he maintained the imbecility of human judgment to be so extreme as to be incapable of any choice or inclination, and would have it perpetually wavering and suspended, considering and receiving all things as indifferent, ‘tis said that he always comported himself after the same manner and countenance: if he had begun a discourse, he would always end what he had to say, though the person he was speaking to had gone away: if he walked, he never stopped for any impediment that stood in his way, being preserved from precipices, the jostle of carts, and other like accidents, by the care of his friends: for, to fear or to avoid anything, had been to shock his own propositions, which deprived the senses themselves of all election and certainty.
It’s very difficult to believe the truth of this report. Montaigne concedes that the account comes from reports themselves derived from hearsay. He took this description of Pyrrho from Diogenes Laertes who drew from someone named Antigonus, and the portrayal is several steps removed from the man himself. But it isn’t that the sources are scarce and tenuous that makes it difficult to believe, but rather that the characterization itself is so improbable. The ancient Greek philosophers pondered the ultimate nature of reality, whether it was matter or thought, many or one, finite or infinite, changeable or immutable but they lived in the same world we do. When walking they sometimes tripped and scraped their palms, when cooking they sometimes burned themselves, when banging their head against a low ceiling they felt a sharp pain. They were as aware and as certain of the ordinary course of cause and effect as anybody else. There is the famous story of Samuel Johnson, upon hearing of how Doctor Berkeley claimed that all objects were ideal rather than material, kicking a large, heavy stone and crying out “I refute it thus.” Johnson refuted nothing because Berkeley, like any philosopher, knew perfectly well that when somebody kicks such a hard, massive object, the result is obstruction, pain, and possibly a broken toe.
Acquaintances of David Hume were often astonished that so thorough and infamous a skeptic turned out to be so worldly, urbane, and genial. He was such a contented, affable gentleman that only a Rousseau could quarrel with him. Hume was also known for being fond of billiards and when he played, despite his skepticism, he little doubted that the cue ball would transfer its momentum to the colored balls upon striking them, and that they would be propelled onward according to the laws of Euclidean geometry and Newtonian physics. The laws of nature prescribe that certain effects follow from certain causes. Most are certain that there is something tying the cause and the effect together. This causality is an intuition, a feeling, a prejudice, or a habit of association. We see the movement of the cue ball, the two balls clicking together, and the movement of the colored ball, but we don’t see the causality. Hume pointed out that the cause and the effect are both perceived, and the causality is assumed but is not itself the object of any perception.
It is induction that leads us to think the effect will proceed from the cause, but simply because it is an induction doesn’t mean that it’s untrustworthy. We’ve learned the laws of nature, and we’re certain that they will hold true in the future just as they have in the past. All our behavior is based on our knowledge of these laws and if they all suddenly changed, we’d be unable to survive. If objects suddenly flitted out of existence, if time looped so that after travelling or laboring all day we ended up at our starting point, if we couldn’t tell which objects were permeable and which objects were impermeable in advance, if the operation and direction of gravity changed without warning or pattern, we’d be unable to cope with a world that’s challenging enough in its predictable form. Very few of us are worried on any of these counts and we are quite sure that the laws of nature will continue to pertain as they always have.
Yet we seem unable to come up with an ultimate basis for these laws. We don’t have a reason that these laws must be the way they are and they can’t be otherwise. This means that the laws of nature are contingent. This doesn’t mean that they sometimes operate and sometimes don’t. It means that they will remain in effect and must be coherent but they still could be completely different than they are. We can imagine possible worlds where gravity is repulsive (as it is at high enough temperatures), where the laws of atom building are different and there is a completely different table of periodic elements, where the four fundamental forces are replaced with completely different interactions. This contingency is unsettling, and in our distress, we shouldn’t be sneered at as a vain and parochial species who want to believe they’re special. Randomness should be unsettling for any thinking life form because thinking involves a search for the simple, for the compressible, for the rational.
Philosophers are as fully aware of how the everyday world works as the rest of mankind. Some like Thales, and Adam Smith are famously absent-minded, but Pyrrho knew full well that a kicking a stone lying in the street in Athens will hurt just as much as kicking a stone in London. That doesn’t mean that philosophy is the business of coming up with bad reasons for what everyone knows. Everyone knows that if a stone is rolled down the street in Athens or London it will eventually slow and come to a stop, but Aristotle believed that the stone moved because of a force acting upon it, while Jean Buridan believed that it moved on its own and stopped because of a force acting on it. The difference is immaterial on the streets of Athens or London but if we escape the Earth’s atmosphere and gravitational field, the difference is critical.
Similarly, some thinkers like Lucretius believe that the world is ultimately matter, and some like Berkeley believe that it is ultimately ideal. Just as Newtonian physics perfectly describes the world of slow-moving, medium-sized objects but breaks down when describing the very small, the very large, and the very fast, so the descriptions of materialism and idealism match our ordinary world equally well but when they are pushed past the boundaries of our experience one of them may be vindicated above the other. Plato or Aristotle, Hegel or Kant, Heraclitus or Parmenides, we may have to venture beyond the borders of our world into the twilight zone to settle the dispute.