Auguste Comte i el positivisme

for things, who is treating other words as if they were things every time he opens his mouth to discuss. No one, unless entirely ignorant of the history of thought, will deny that the mistaking of abstractions for realities pervaded speculation all through antiquity and the middle ages. The mistake was generalized and systematized in the famous Ideas of Plato. The Aristotelians carried it on. Essences, quiddities, virtues residing in things, were accepted as a _bonâ fide_ explanation of phaenomena. Not only abstract qualities, but the concrete names of genera and species, were mistaken for objective existences. It was believed that there were General Substances corresponding to all the familiar classes of concrete things: a substance Man, a substance Tree, a substance Animal, which, and not the individual objects so called, were directly denoted by those names. The real existence of Universal Substances was the question at issue in the famous controversy of the later middle ages between Nominalism and Realism, which is one of the turning points in the history of thought, being its first struggle to emancipate itself from the dominion of verbal abstractions. The Realists were the stronger party, but though the Nominalists for a time succumbed, the doctrine they rebelled against fell, after a short interval, with the rest of the scholastic philosophy. But while universal substances and substantial forms, being the grossest kind of realized abstractions, were the soonest discarded, Essences, Virtues, and Occult Qualities long survived them, and were first completely extruded from real existence by the Cartesians. In Descartes' conception of science, all physical phaenomena were to be explained by matter and motion, that is, not by abstractions but by invariable physical laws: though his own explanations were many of them hypothetical, and turned out to be erroneous.…