Looking at the relative wealth of fragments preserved from Empedocles, one gets the impression of a thinker of great resourcefulness and imagination. No aspect of the physical world escaped his inquiring eye. Yet the mass of physical facts were brought under explanatory principles that display, to the modern eye, the virtues of simplicity and elegance. Furthermore, some of the explanations which Empedocles offers startlingly anticipate developments in modern science. In comparison with the Milesians, we are, without a doubt, dealing with a theory of an altogether higher level of sophistication. — But then again, that is something one would have naturally expected, given that Empedocles had the pioneering work of his predecessors to build from. The question is, What is the philosophical value of his achievement?

Let us start by looking at the reasons for being impressed. Empedocles abandoned the notion of a single stuff — whether water, or the Apeiron, or air, or fire — that was able to undergo seemingly unlimited transformations, for a theory of four basic elements or 'roots', each capable of combining with one or more of the others in various proportions. Each element retained its essential, defining properties, yet new properties emerged from their quasi-chemical compounds. It is important to appreciate just how much of an imaginative leap this involved. If you mix earth and water, for example, you get something that all-too obviously owes its properties to the properties of each of its ingredients. If you attempt to 'mix' water and fire, on the other hand, either the fire is quenched or the water boils. Having conceded that earth can only ever be earth, water can only ever be water, air can only ever be air, fire can only ever be fire, how could Empedocles have hoped to persuade his contemporaries to accept what was, according to common sense, the seemingly absurd proposition that human blood, to take a notable example, actually contains earth, water, air and fire? — There is really no answer except to claim that the theory of four elements or roots was the best explanation, in the face of what appeared insuperable objections, deriving from the arguments of Parmenides, to all previous theories.

It was not until experiment such as Lavoisier's, in the eighteenth century, where precisely measured quantities of mercury and oxygen where heated to produce mercuric oxide (a red powder), and the red powder reduced by means of heating back to the original quantities of mercury and oxygen, that a theory of unchanging primary elements, such as Empedocles' account of the four 'roots', could have been made at all plausible in terms of actual experience. (Lavoisier was actually concerned to disprove the notorious 'phlogiston' theory, according to which processes now known as 'oxidation', such as burning, involved losing a substance called phlogiston. It fell to the English chemist, Thomas Dalton, to formulate the modern atomic hypothesis in 1804.) Even in the face of Lavoisier's chemical experiment, a contemporary philosopher sceptical of Empedocles' theory would have been free to insist on the Heraclitean line that, in reacting together, the mercury and oxygen perish, and in their place the red powder comes to be. When the red powder is heated, the process of perishing and coming to be is reversed. — In fact, the only evidence Empedocles' would have been able to call upon in support of his theory of elements and compounds were far less persuasive examples of the creation of foods or alloys with novel properties out of fixed proportions of ingredients in cooking or metallurgy.

But suppose Empedocles had been able to perform Lavoisier's experiment. A determined sceptic might choose take a different line and ask where the mercury and oxygen are in mercuric oxide. McKirahan quotes Aristotle's argument that the continued existence of elements in a composition is only intelligible if the elements are arranged 'as a wall comes to be out of bricks and stones'. Either the tiny bits of, say, pure fire and pure earth — or pure mercury and pure oxygen — will be indivisible, or else they will be divisible 'but will never in fact be divided' (p. 265). Empedocles gives no evidence of having considered the former alternative. Yet the latter alternative is very unsatisfactory. In a mixture, whether solid or liquid, the indefinite variability of the size, or indeed the relative size of the constituent particles is one of the reasons why the ingredients can be mixed in indefinitely varying proportions. If the particles of Empedoclean elements constituting a compound remain divisible, how can one avoid the conclusion that the size of the particles will naturally vary? In that case, how are the fixed proportions maintained?

The difference between mixtures and real compounds can be illustrated if one takes the analogy with building a wall literally. Making a compound out of, say, two elements is like building a wall out of two different shapes of brick. The bricks must have fixed sizes relative to one another, otherwise they will not fit together: instead of a compound, a solid wall, you just get a pile of bricks. But, equally, the bricks in one wall or compound must be commensurate with the bricks in any other compound made of the same constituents. The mercury in any one sample of mercuric oxide — or the fire in any one sample of human blood — is interchangeable with the mercury, or fire, in any other sample. Surely, if Empedocles had thought this problem through, he would have been inevitably drawn — as was Dalton — to some form of atomic hypothesis.

The second notable feature in Empedocles' physical theory is the positing of two universal forces, Love and Strife. We shall look at their role in cosmology in a moment. The prior question, however, is why such forces are needed in order to account for the processes that we observe to occur in the world around us. The modern equivalent of Love might be magnetism, gravity, chemical bonding, as well as the forces that hold atoms together. Examples of Strife would be electrostatic or magnetic repulsion, and the forces that account for the impenetrability of atoms. Empedocles had obviously not needed to think what 'holds an atom together', or what is involved in an atom's 'occupying' a certain space to the exclusion of anything else. Gravity would have been an excellent example of 'Love', but like his predecessors, Empedocles' had not thought to ask why 'things fall down'.

The only physical examples Empedocles could have called upon of action at a distance would thus have been the relatively anomalous cases of Thales' iron and magnet, and rubbed amber. The available evidence — derived from the manipulation of tools, or the observation of natural events — pointed far more strongly to a purely mechanical view of collisions and rebounds, interlockings and disentanglements, where all physical change is accounted for in terms of actual pushes and pulls. (Human love, it must be said, did provide Empedocles with a wonderful model for action at a distance!) Now while it is undoubtedly impressive, to modern eyes, that Empedocles was able to anticipate developments in physical theory to such a surprising extent, one could argue that his theory flied in the face of the available evidence. This was precisely the conclusion that the Atomists reached.

While Love and Strife served to explain how compounds are formed and dissolved — Empedocles evidently feeling that the special properties of the individual elements as manifested on a microscopic level were not adequate to this purpose — their main role is in Empedocles poetically inspiring view of the universe as a never-ending cycle between the extremes of complete unity of four elements — 'a rounded sphere rejoicing in its joyous solitude' (KRS sec. 358. p. 295; cf. McK sec. 14.50, p. 242) — and total separation. In between these two extremes a cosmos, together with a world of plant and animal life, forms out of unity, dissolves into separation, then forms out of separation and merges into unity, whence the whole cycle begins again.

Thus, human life alternately experiences the phases of increasing Love and increasing Strife. (According to Aristotle's testimony, we are now in the phase of increasing Strife, McK sec. 14.151, p. 273.) — Sometimes the sheer power of a philosophic vision brushes aside worries about reconciling the account with the facts of ordinary experience, or the logical problems raised. The big picture is far more important than the details. That the next phase of the cosmic cycle will lead to the God-like state of joyous unity is a source of hope and an object of religious awe. Surely that was Empedocles' message.

However, it is now disputed by some scholars that Empedocles maintained such a double cosmogony and double zoogony (notably in KRS pp. 297 ff.; although McK and JB continue to support the disputed view). The evidence is inconclusive, depending on exactly how the fragments from Empedocles' writings are pieced together. Without claiming to give an exhaustive evaluation of the available evidence on each side, one may suggest a consideration that can at least be employed to resist the revisionist interpretation. It is simply that the supposed implausibility of a double cosmogony and zoogony depends upon our taking a grossly anachronistic view.

Having discovered in Empedocles' account of matter startling anticipations of modern theories, one naturally looks for anticipations of modern cosmology and biology. And, sure enough, there is the Big Bang (the disruption of the sphere by the appearance of Strife), the separation of the basic materials of the cosmos, the formation of the earth and heavens, then the evolution of life. How clever of Empedocles, we think, to have anticipated the theory of evolution by natural selection! We silently pass over the hypothesis — which would surely have seemed no less incredible to his contemporaries than it does to us (and indeed did so to Aristotle) — that prior to the process of natural selection, 'unattached' eyes and limbs were formed directly under the influence of Love out of their ingredient elements, and subsequently 'wandered' around before joining together in various haphazard combinations (KRS secs. 375-9, pp. 303-4; McK secs. 14.76-9, pp. 245-6). Surely no-one would expect his readers to accept that amazing story if was not an obligatory part of the bigger picture.

As additional evidence for our view, one would point out that the springing up of 'whole natured shapes' (KRS sec. 381, p. 304; cf. McK sec. 14.81, p. 246) provides a counterpoint theory of the evolution of animal life that simply does not fit any stage of the above theory, but gives every impression of an account describing the process whereby under the influence of Strife, the Sphere became articulated into increasingly determinate forms. Thus, Strife creates determinate biological forms by separating the implicit articulations a prior unity, while Love creates determinate biological forms by joining together the ingredients arising from a prior state of separation. We are the sad descendants of beings that emerged from the disrupted state of perfect unity. All we have to look forward to is increased Strife, and finally obliteration into our component elements. But after us will come the beings who can joyfully anticipate a time when they will once again merge into the god-like, blissful state of pure Love.