Picture a practical joke, played by an older brother on his younger brother. The little brother is having cereal for breakfast. He pours out a serving from the cereal box, which is nearly full, and so has some small heft. The big brother distracts him, “Look behind you!” As the little brother looks away, the big brother swaps boxes. The replacement is nearly empty, but looks the same. A bit later, the little brother goes to refill his bowl, but he jerks the lighter box up way too quickly, then over-corrects, sending bits of cereal flying up, then falling down in a shower into his hair, over the kitchen table, and onto the floor. Big brother has a good laugh.
The little brother’s senses might seem, at first, to have told him that the cereal box was both heavy and light at the same time and in the same way. But then he checks his premises. Things in the world don’t normally behave like this.
Of the two values most distinctive and essential to Western civilization, individual rights and reason, reason is the more fundamental. What is reason? I know of no better definition than that offered by the philosopher Ayn Rand: “Reason is the faculty that identifies and integrates the material provided by man’s senses.” Reason operates by a particular method: logic. “Logic is the art of non-contradictory identification.” What does this mean in practice?
To use reason is to investigate or examine the world by means of the senses and then to check the various (provisional) conclusions one comes to about the world against each other. If there is a conflict discovered among these provisional conclusions, then logic is applied to sort it out. Contradictions do not exist in reality; a thing cannot be both heavy and light, for example, at the same time and in the same way.
A reasonable little brother might realize this. If the cereal box that had been nearly full was suddenly nearly empty, perhaps it wasn’t the same box after all? Or perhaps someone had emptied it? And since the little brother knows he had neither emptied nor switched it himself … it would suggest that big brother should get a bowl of milk and cereal bits dumped in his lap, right away, if not sooner.
Man is the “rational animal.” Human beings reason; this has been true since man has existed, and has been true in every culture and in every civilization. If we did not try to make an ordered, logical sense out of our sensory experience of the world, but instead treated every phenomenon as entirely unique, entirely unrelated to every other phenomenon, we would not have lasted as a species. It would have been impossible even to feed ourselves, since we would have had no means for concluding, for example, that because the first rock we bit wasn’t food, the next one wouldn’t somehow turn out to be.
While people in civilizations other than Classical civilization (which is Western civilization’s antecedent in this context), used reason to develop sophisticated life-improving technologies and enduring socio-political structures, only in Western civilization would reason itself become a core value, and only in Western civilization would systematic reasoning about the natural world become a prominent area of inquiry. The historical record is sparse, but this process seems to have started with a man called Thales, who lived in the 6th Century BCE, in what is now Turkey.
Thales seems to have been concerned with finding what Aristotle would later call the archÄ“, or ruling principle, behind matter. He wanted to understand what made all of the physical stuff in the world — rocks, trees, animals, men, etc. — exist as it existed, and change as it changed. Note that it is precisely this line of inquiry that recently led to the discovery of the Higgs boson. In other words, modern science derives directly from the attempts to answer the questions that Thales and others in Classical civilization started asking. Thales is often recognized (more because it is convenient to pin the movement to a name we know, and less because we actually know that Thales started the movement) as the founder of Western philosophy.
Fashions come and go, and probably the fashion for this style of philosophy around the islands and coasts of 5th-Century Mediterranean would have died out eventually, or it would have been absorbed into other cultural traditions, such as local religions or schools of engineering and other practical arts, if the Greek-speaking people of that area had not become enormously wealthy (by the standards of the time), and if they had not developed a new social technology: democracy. With enormous wealth came both the desire, on the part of the rich, to keep as much of it as possible, and the leisure time to come up with novel strategies for doing so. With democracy came arguments, lots of arguments, and often these arguments were about wealth, who should have it, and what to do with it. When wealth, leisure, democracy, and the fashion for philosophy came together in Classical-age Athens, the most prominent city-state in the Greek-speaking world, a cultural crucible began to heat. Its molten mixture, when it was poured out, would be forged into weapons and tools unlike anything the world had ever seen. Many centuries later, with these weapons and tools, the West would conquer the world.