Story of Psychology - Morton Hunt [8]
Within a century, some philosophers and the physician Alcmaeon suggested that the brain, rather than the heart or other organs, as earlier believed, was where nous existed and where thinking goes on. Some thought it was a kind of spirit, others that it was the very stuff of the brain itself, but in neither case did they say anything about how memory, reasoning, or other thought processes take place. They were preoccupied by the more elementary question of whence—since not from the gods—the mind obtains the raw materials of thought.
Alcmaeon
Their general answer was sense experience. Alcmaeon, for one, said that the sense organs send perceptions to the brain, where, by means of thinking, we interpret them and derive ideas from them. What intrigued him and others was how the perceptions get from the sense organs to the brain. Unaware of nerve impulses, even though he had discovered the optic nerve, and believing, on abstract metaphysical grounds, that air was the vital component of mind, he decided that perceptions must travel along air channels from the sense organs to the brain: No matter that he never saw any and that no such channels exist; reason told him it must be so. (Later Greek anatomists would refer to the air, pneuma, they thought was in the nerves and brain as “animal spirits,” and in one form or another this belief would dominate thinking about the nervous system until the eighteenth century.) Although Alcmaeon’s theory was wholly incorrect, his emphasis on perception as the source of knowledge was the beginning of epistemology—the study of how we acquire knowledge—and laid the ground for a debate about that topic that has gone on ever since.
Protagoras
Alcmaeon’s ideas were borne around the far-flung Greek cities by travelers; soon, philosophers in many places were devising their own explanations of how perception takes place, and a number of them asserted that it was the basis of all knowledge. But some saw the troubling implications of this view. Protagoras (485–411), best known of the Sophists (a term that then meant not fallacious reasoners but “teachers of wisdom”), unsettled his contemporaries and pupils by pointing out that, since perception was the only source of knowledge, there could be no absolute truth. His famous apothegm, “Man is the measure of all things,” meant, he explained, that any given thing is to me what it appears to me to be, and, if it appears different to you, is what it seems to you to be. Each perception is true—for each perceiver. Philosophers were willing to debate the point, but politicians considered it subversive. When Protagoras, visiting Athens, tactlessly applied his theory to religion, saying there was no way for him to know whether the gods exist or not, the outraged Assembly banished him and burned his writings. He fled and drowned at sea en route to Sicily.
Democritus
Others carried on that line of inquiry, devising explanations of how perception takes place and maintaining that, since knowledge is based on perception, all truths are relative and subjective. The most sophisticated of such musings were those of Democritus (460–362) of Abdera, Thrace, the most learned man of his time. Vastly amused by the follies of humankind, he was known as the “laughing philosopher.” His main claim to fame, actually, derives not from his psychological reflections but from his extraordinary guess that all matter is composed of invisible particles (atoms) of different shapes linked together in different combinations, a conclusion he came to, without any experimental