Aristotle's Theory of Universals is a classical solution to the Problem of Universals. Universals are the characteristics or qualities that ordinary objects or things have in common. They can be identified in the types, properties, or relations observed in the world. For example, imagine there is a bowl of red apples resting on a table. Each apple in that bowl will have many similar qualities, such as their red coloring or "redness". They will share some degree of the quality of "ripeness" depending on their age. They may also be at varying degrees of age, which will affect their color, but they will all share a universal "appleness". These qualities are the universals that the apples hold in common.
The Problem of Universals asks three questions. Do universals exist? If they exist, where do they exist? Also, if they exist, how do we obtain knowledge of them? In Aristotle's view, universals are incorporeal and universal, but only exist only where they are instantiated; they exist only in things. Aristotle said that a universal is identical in each of its instances. All red things are similar in that there is the same universal, redness, in each thing. There is no Platonic Form of redness, standing apart from all red things; instead, each red thing has a copy of the same property, redness. For the Aristotelian, knowledge of the universals is not obtained from a supernatural source. It is obtained from experience by means of active intellect.
The purpose of this thread is to discuss whether Epicurus would have agreed or disagreed with this theory.
References to consider Include:
Epicurus' Letter to Herodotus:
Moreover, as regards shape and colour and size and weight and all other things that are predicated of body, as though they were concomitant properties either of all things or of things visible or recognizable through the sensation of these qualities, we must not suppose that they are either independent existences (for it is impossible to imagine that), nor that they absolutely do not exist, nor that they are some other kind of incorporeal existence accompanying body, nor that they are material parts of body: rather we should suppose that the whole body in its totality owes its own permanent existence to all these, yet not in the sense that it is composed of properties brought together to form it (as when, for instance, a larger structure is put together out of the parts which compose it, whether the first units of size or other parts smaller than itself, whatever it is), but only, as I say, that it owes its own permanent existence to all of them.
All these properties have their own peculiar means of being perceived and distinguished, provided always that the aggregate body goes along with them and is never wrested from them, but in virtue of its comprehension as an aggregate of qualities acquires the predicate of body.
Furthermore, there often happen to bodies and yet do not permanently accompany them accidents, of which we must suppose neither that they do not exist at all nor that they have the nature of a whole body, nor that they can be classed among unseen things nor as incorporeal.
So that when according to the most general usage we employ this name, we make it clear that accidents have neither the nature of the whole, which we comprehend in its aggregate and call body, nor that of the qualities which permanently accompany it, without which a given body cannot be conceived.
But as the result of certain acts of apprehension, provided the aggregate body goes along with them, they might each be given this name, but only on occasions when each one of them is seen to occur, since accidents are not permanent accompaniments.
And we must not banish this clear vision from the realm of existence, because it does not possess the nature of the whole to which it is joined nor that of the permanent accompaniments, nor must we suppose that such contingencies exist independently (for this is inconceivable both with regard to them and to the permanent properties), but, just as it appears in sensation, we must think of them all as accidents occurring to bodies, and that not as permanent accompaniments, or again as having in themselves a place in the ranks of material existence; rather they are seen to be just what our actual sensation shows their proper character to be.
Moreover, you must firmly grasp this point as well; we must not look for time, as we do for all other things which we look for in an object, by referring them to the general conceptions which we perceive in our own minds, but we must take the direct intuition, in accordance with which we speak of “a long time” or “a short time,” and examine it, applying our intuition to time as we do to other things.
Neither must we search for expressions as likely to be better, but employ just those which are in common use about it.
Nor again must we predicate of time anything else as having the same essential nature as this special perception, as some people do, but we must turn our thoughts particularly to that only with which we associate this peculiar perception and by which we measure it.
For indeed this requires no demonstration, but only reflection, to show that it is with days and nights and their divisions that we associate it and likewise also with internal feelings or absence of feeling, and with movements and states of rest; in connection with these last again we think of this very perception as a peculiar kind of accident, and in virtue of this we call it time.
Lucretius On The Nate of Things, Book One (Munro)::
 All nature then, as it exists by itself, is founded on two things: there are bodies and there is void in which these bodies are placed and through which they move about. For that body exists by itself the general feeling of man kind declares; and unless at the very first belief in this be firmly grounded, there will be nothing to which we can appeal on hidden things in order to prove anything by reasoning of mind. Then again, if room and space which we call void did not exist, bodies could not be placed anywhere nor move about at all to any side; as we have demonstrated to you a little before.
 Moreover there is nothing which you can affirm to be at once separate from all body and quite distinct from void, which would so to say count as the discovery of a third nature. For whatever shall exist, this of itself must be something or other. Now if it shall admit of touch in however slight and small a measure, it will, be it with a large or be it with a little addition, provided it do exist, increase the amount of body and join the sum. But if it shall be intangible and unable to hinder any thing from passing through it on any side, this you are to know will be that which we call empty void.
 Again whatever shall exist by itself, will either do something or will itself suffer by the action of other things, or will be of such a nature as things are able to exist and go on in. But no thing can do and suffer without body, nor aught furnish room except void and vacancy. Therefore beside void and bodies no third nature taken by itself can be left in the number of things, either such as to fall at any time under the ken of our senses or such as any one can grasp by the reason of his mind. For whatever things are named, you will either find to be properties linked to these two things or you will see to be accidents of these things. That is a property which can in no case be disjoined and separated without utter destruction accompanying the severance, such as the weight of a stone, the heat of fire, the fluidity of water. Slavery on the other hand, poverty and riches, liberty war concord and all other things which may come and go while the nature of the thing remains unharmed, these we are wont, as it is right we should, to call accidents.
 Time also exists not by itself, but simply from the things which happen the sense apprehends what has been done in time past, as well as what is present and what is to follow after. And we must admit that no one feels time by itself abstracted from the motion and calm rest of things.
 So when they say that the daughter of Tyndarus was ravished and the Trojan nations were subdued in war, we must mind that they do not force us to admit that these things are by themselves, since those generations of men, of whom these things were accidents, time now gone by has irrevocably swept away. For whatever shall have been done may be termed an accident in one case of the Teucran people, in another of the countries simply.
 Yes for if there had been no matter of things and no room and space in which things severally go on, never had the fire, kindled by love of the beauty of Tyndarus’ daughter, blazed beneath the Phrygian breast of Alexander and lighted up the famous struggles of cruel war, nor had the timber horse unknown to the Trojans wrapt Pergama in flames by its night-issuing brood of sons of the Greeks; so that you may clearly perceive that all actions from first to last exist not by themselves and are not by themselves in the way that body is, nor are terms of the same kind as void is, but are rather of such a kind that you may fairly call them accidents of body and of the room in which they severally go on.
 Bodies again are partly first-beginnings of things, partly those which are formed of a union of first beginnings. But those which are first-beginnings of things no force can quench: they are sure to have the better by their solid body. Although it seems difficult to believe that aught can be found among things with a solid body. For the lightning of heaven passes through the walls of houses, as well as noise and voices; iron grows red-hot in the fire and stones burn with fierce heat and burst asunder the hardness of gold is broken up and dissolved by heat; the ice of brass melts vanquished by the flame; warmth and piercing cold ooze through silver, since we have felt both, as we held cups with the hand indue fashion and the water was poured down into them. So universally there is found to be nothing solid in things. But yet because true reason and the nature of things constrains, attend until we make clear in a few verses that there are such things as consist of solid and everlasting body, which we teach are seeds of things and first-beginnings, out of which the whole sum of things which now exists has been produced.
Frances Wright, A Few Days In Athens, Chapter 15:
“It might seem strange,” said Metrodorus, “that the pedantry of Aristotle should find so many imitators, and his dark sayings so many believers, in a city, too, now graced and enlightened by the simple language, and simple doctrines of an Epicurus. — But the language of truth is too simple for inexperienced ears. We start in search of knowledge, like the demigods of old in search of adventure, prepared to encounter giants, to scale mountains, to pierce into Tartarean gulfs, and to carry off our prize from the grip of some dark enchanter, invulnerable to all save to charmed weapons and deity-gifted assailants. To find none of all these things, but, in their stead, a smooth road through a pleasant country, with a familiar guide to direct our curiosity, and point out the beauties of the landscape, disappoints us of all exploit and all notoriety; and our vanity turns but too often from the fair and open champaigne, into error’s dark labyrinths, where we mistake mystery for wisdom, pedantry for knowledge, and prejudice for virtue.”
Mind or thought I consider a quality of that matter constituting the existence we call a man, which quality we find in a varying degree in other existences; many, perhaps all animals, possessing it. Life is another quality, or combination of qualities, of matter, inherent in — we know not how many existences. We find it in vegetables; we might perceive it even in stones, could we watch their formation, growth, and decay. We may call that active principle, pervading the elements of all things, which approaches and separates the component particles of the ever-changing, and yet ever-enduring world — life. Until you discover some substance, which undergoes no change, you cannot speak of inert matter: it can only be so, at least, relatively, — that is, as compared with other substances.”
“The classing of thought and life among the qualities of matter is new to me.”
“What is in a substance cannot be separate from it. And is not all matter a compound of qualities? Hardness, extension, form, color, motion, rest — take away all these, and where is matter? To conceive of mind independent of matter, is as if we should conceive of color independent of a substance colored: What is form, if not a body of a particular shape? What is thought, if not something which thinks? Destroy the substance, and you destroy its properties; and so equally — destroy the properties, and you destroy the substance. To suppose the possibility of retaining the one, without the other, is an evident absurdity.”
“The error of conceiving a quality in the abstract often offended me in the Lyceum,” returned the youth, “but I never considered the error as extending to mind and life, any more than to vice and virtue.”
Richard Dawkins 2014 Article from Edge.org: "What Scientific Idea Is Ready For Retirement?"
Essentialism—what I’ve called "the tyranny of the discontinuous mind"—stems from Plato, with his characteristically Greek geometer’s view of things. For Plato, a circle, or a right triangle, were ideal forms, definable mathematically but never realised in practice. A circle drawn in the sand was an imperfect approximation to the ideal Platonic circle hanging in some abstract space. That works for geometric shapes like circles, but essentialism has been applied to living things and Ernst Mayr blamed this for humanity’s late discovery of evolution—as late as the nineteenth century. If, like Aristotle, you treat all flesh-and-blood rabbits as imperfect approximations to an ideal Platonic rabbit, it won’t occur to you that rabbits might have evolved from a non-rabbit ancestor, and might evolve into a non-rabbit descendant. If you think, following the dictionary definition of essentialism, that the essence of rabbitness is "prior to" the existence of rabbits (whatever "prior to" might mean, and that’s a nonsense in itself) evolution is not an idea that will spring readily to your mind, and you may resist when somebody else suggests it.