If Aristotle was not a scientist, he was especially not a chemist: "Aristotle's chemistry, like Socrates' book, does not exist. ... the absence of material of a specifically chemical character in ancient Greek natural philosophy has largely escaped the attention it deserves." [Horne 1966]. Aristotle wrote on subjects which are now part of the disciplines of biology and physics, but not on chemical subjects, and in this respect, he was no different from other figures in ancient Greek philosophy.
So why begin a book of case studies in scientific method illustrating chemical themes with a selection which is neither scientific nor chemical? Aristotle's conception of the elements, even though it was concerned primarily with physical aspects of matter, was one which later chemists had to confront. (See next chapter.) Besides, this collection explores the themes of atoms and elements from both physical and chemical perspectives. Finally, the unscientific discourse of Aristotle can serve as a point of reference and contrast to the scientific discourses presented in the remainder of the book.
For the complex substances whose formation and maintenance are due to natural processes all presuppose the perceptible bodies as the condition of their coming-to-be and passing-away: but philosophers disagree in regard to the matter which underlies these perceptible bodies. Some maintain it is single, supposing it to be, e.g. Air or Fire, or an "intermediate" between these two (but still a body with a separate existence). Others, on the contrary, postulate two or more materials--ascribing to their "association" and "dissociation," or to their "alteration," the coming-to-be and passing-away of things. (Some, for instance, postulate Fire and Earth: some add Air, making three: and some, like Empedokles, reckon Water as well, thus postulating four.)
Now we may agree that the primary materials, whose change (whether it be "association and dissociation" or a process of another kind) results in coming-to-be and passing-away, are rightly described as "originative sources, i.e. elements." But (i) those thinkers are in error who postulate, beside the bodies we have mentioned, a single matter--and that corporeal and separable matter. For this "body" of theirs cannot possibly exist without a "perceptible contrariety": this "Boundless," which some thinkers identify with the "original real," must be either light or heavy, either cold or hot. And (ii) what Plato has written in the Timaeus is not based on any precisely-articulated conception. For he has not stated clearly whether his "Omnirecipient" exists in separation from the "elements"; nor does he make any use of it. He says, indeed, that it is a substratum prior to the so-called "elements"--underlying them, as gold underlies the things that are fashioned of gold. (And yet this comparison, if thus expressed, is itself open to criticism. Things which come-to-be and pass-away cannot be called by the name of the material out of which they have come-to-be: it is only the results of "alteration" which retain the name of the substratum whose "alterations" they are. However, he actually says that "far the truest account is to affirm that each of them is 'gold.'") Nevertheless he carries his analysis of the "elements"--solids though they are--back to "planes," and it is impossible for "the Nurse" (i.e. the primary matter) to be identical with "the planes."
Our own doctrine is that although there is a matter of the perceptible bodies (a matter out of which the so-called "elements" come-to-be), it has no separate existence, but is always bound up with a contrariety. A more precise account of these presuppositions has been given in another work: we must, however, give a detailed explanation of the primary bodies as well, since they too are similarly derived from the matter. We must reckon as an "originative source" and as "primary" the matter which underlies, though it is inseparable from, the contrary qualities: for "the hot" is not matter for "the cold" nor "the cold" for "the hot," but the substratum is matter for them both. We therefore have to recognize three "originative sources": firstly that which is potentially perceptible body, secondly the contrarieties (I mean, e.g., heat and cold), and thirdly Fire, Water, and the like. Only "thirdly," however: for these bodies change into one another (they are not immutable as Empedokles and other thinkers assert, since "alteration" would then have been impossible), whereas the contrarieties do not change.
Nevertheless, even so the question remains: What sorts of contrarieties, and how many of them, are to be accounted "originative sources" of body? For all the other thinkers assume and use them without explaining why they are these or why they are just so many.
Accordingly, we must segregate the tangible differences and contrarieties, and distinguish which amongst them are primary. Contrarieties correlative to touch are the following: hot-cold, dry-moist, heavy-light, hard-soft, viscous-brittle, rough-smooth, coarse-fine. Of these (i) heavy and light are neither active nor susceptible. Things are not called "heavy" and "light" because they act upon, or suffer action from, other things. But the "elements" must be reciprocally active and susceptible, since they "combine" and are transformed into one another. On the other hand (ii) hot and cold, and dry and moist, are terms, of which the first pair implies power to act and the second pair susceptibility. "Hot" is that which "associates" things of the same kind (for "dissociating," which people attribute to Fire as its function, is "associating" things of the same class, since its effect is to eliminate what is foreign), while "cold" is that which brings together, i.e. "associates," homogeneous and heterogeneous things alike. And moist is that which, being readily adaptable in shape, is not determinable by any limit of its own: while "dry" is that which is readily determinable by its own limit, but not readily adaptable in shape.
From moist and dry are derived (iii) the fine and coarse, viscous and brittle, hard and soft, and the remaining tangible differences. For (a) since the moist has no determinate shape, but is readily adaptable and follows the outline of that which is in contact with it, it is characteristic of it to be "such as to fill up." Now "the fine" is "such as to fill up." For "the fine" consists of subtle particles; but that which consists of small particles is "such as to fill up," inasmuch as it is in contact whole with whole--and "the fine" exhibits this character in a superlative degree. Hence it is evident that the fine derives from the moist, while the coarse derives from the dry. Again (b) "the viscous" derives from the moist: for "the viscous" (e.g. oil) is a "moist" modified in a certain way. "The brittle," on the other hand, derives from the dry: for "brittle" is that which is completely dry--so completely, that its solidification has actually been due to failure of moisture. Further (c) "the soft" derives from the moist. For "soft" is that which yields to pressure by retiring into itself, though it does not yield by total displacement as the moist does--which explains why the moist is not "soft," although "the soft" derives from the moist. "The hard," on the other hand, derives from the dry: for "hard" is that which is solidified, and the solidified is dry.
The terms "dry" and "moist" have more senses than one. For "the damp," as well as the moist, is opposed to the dry: and again "the solidified," as well as the dry, is opposed to the moist. But all these qualities derive from the dry and moist we mentioned first. For (i) the dry is opposed to the damp: i.e. "damp" is that which has foreign moisture on its surface ("sodden" being that which is penetrated to its core), while "dry" is that which has lost foreign moisture. Hence it is evident that the damp will derive from the moist, and "the dry" which is opposed to it will derive from the primary dry. Again (ii) the "moist" and the solidified derive in the same way from the primary pair. For "moist" is that which contains moisture of its own deep within it ("sodden" being that which is deeply penetrated by foreign moisture), whereas "solidified" is that which has lost this inner moisture. Hence these too derive from the primary pair, the "solidified" from the dry and the "liquefiable" from the moist.
It is clear, then, that all the other differences reduce to the first four, but that these admit of no further reduction. For the hot is not essentially moist or dry, nor the moist essentially hot or cold: nor are the cold and the dry derivative forms, either of one another or of the hot and the moist. Hence these must be four.
In fact, however, fire and air, and each of the bodies we have mentioned, are not simple, but blended. The "simple" bodies are indeed similar in nature to them, but not identical with them. Thus the "simple" body corresponding to fire is "such-as-fire," not fire: that which corresponds to air is "such-as-air:" and so on with the rest of them. But fire is an excess of heat, just as ice is an excess of cold. For freezing and boiling are excesses of heat and cold [sic] respectively. Assuming, therefore, that ice is a freezing of moist and cold, fire analogously will be a boiling of dry and hot: a fact, by the way, which explains why nothing comes-to-be either out of ice or out of fire.
The "simple" bodies, since they are four, fall into two pairs which belong to the two regions, each to each: for Fire and Air are forms of the body moving towards the "limit," while Earth and Water are forms of the body which moves towards the "centre." Fire and Earth, moreover, are extremes and purest: Water and Air, on the contrary are intermediates and more like blends. And, further, the members of either pair are contrary to those of the other, Water being contrary to Fire and Earth to Air; for the qualities constituting Water and Earth are contrary to those that constitute Fire and Air. Nevertheless, since they are four, each of them is characterized par excellence a single quality: Earth by dry rather than by cold, Water by cold rather than by moist, Air by moist rather than by hot, and Fire by hot rather than by dry.
Now it is evident that all of them are by nature such as to change into one another: for coming-to-be is a change into contraries and out of contraries, and the "elements" all involve a contrariety in their mutual relations because their distinctive qualities are contrary. For in some of them both qualities are contrary--e.g. in Fire and Water, the first of these being dry and hot, and the second moist and cold: while in others one of the qualities (though only one) is contrary--e.g. in Air and Water, the first being moist and hot, and the second moist and cold. It is evident, therefore, if we consider them in general, that every one is by nature such as to come-to-be out of every one: and when we come to consider them severally, it is not difficult to see the manner in which their transformation is effected. For, though all will result from all, both the speed and the facility of their conversion will differ in degree.
Thus (i) the process of conversion will be quick between those which have interchangeable "complementary factors," but slow between those which have none. The reason is that it is easier for a single thing to change than for many. Air, e.g., will result from Fire if a single quality changes: for Fire, as we saw, is hot and dry while Air is hot and moist, so that there will be Air if the dry be overcome by the moist. Again, Water will result from Air if the hot be overcome by the cold: for Air, as we saw, is hot and moist while Water is cold and moist, so that, if the hot changes, there will be Water. So too, in the same manner, Earth will result from Water and Fire from Earth, since the two "elements" in both these couples have interchangeable "complementary factors." For Water is moist and cold while Earth is cold and dry--so that, if the moist be overcome, there will be Earth: and again, since Fire is dry and hot while Earth is cold and dry, Fire will result from Earth if the cold pass-away.
It is evident, therefore, that the coming-to-be of the "simple" bodies will be cyclical; and that this cyclical method of transformation is the easiest, because the consecutive "elements" contain interchangeable "complementary factors." On the other hand (ii) the transformation of Fire into Water and of Air into Earth, and again of Water and Earth into Fire and Air respectively, though possible, is more difficult because it involves the change of more qualities. For if Fire is to result from Water, both the cold and the moist must pass-away: and again, both the cold and the dry must pass-away if Air is to result from Earth. So, too, if Water and Earth are to result from Fire and Air respectively--both qualities must change.
This second method of coming-to-be, then, takes a longer time. But (iii) if one quality in each of two "elements" pass-away, the transformation, though easier, is not reciprocal. Still, from Fire plus Water there will result Earth and Air, and from Air plus Earth Fire and Water. For there will be Air, when the cold of the Water and the dry of the Fire have passed-away (since the hot of the latter and the moist of the former are left): whereas, when the hot of the Fire and the moist of the Water have passed-away, there will be Earth, owing to the survival of the dry of the Fire and the cold of the Water. So, too, in the same Way, Fire and Water will result from Air plus Earth. For there will be Water, when the hot of the Air and the dry of the Earth have passed-away (since the moist of the former and the cold of the latter are left): whereas, when the moist of the Air and the cold of the Earth have passed-away, there will be Fire, owing to the survival of the hot of the Air and the dry of the Earth--qualities essentially constitutive of Fire. Moreover, this mode of Fire's coming-to-be is confirmed by perception. For flame is par excellence Fire: but flame is burning smoke, and smoke consists of Air and Earth.
No transformation, however, into any of the "simple" bodies can result from the passing-away of one elementary quality in each of two "elements" when they are taken in their consecutive order, because either identical or contrary qualities are left in the pair: but no "simple" body can be formed either out of identical, or out of contrary, qualities. Thus no "simple" body would result, if the dry of Fire and the moist of Air were to pass-away: for the hot is left in both. On the other hand, if the hot pass-away out both, the contraries--dry and moist--are left. A similar result will occur in all the others too: for all the consecutive "elements" contain one identical, and one contrary, quality. Hence, too, it clearly follows that, when one of the consecutive "elements" is transformed into one, the coming-to-be is effected by the passing-away of a single quality: whereas, when two of them are transformed into a third, more than one quality must have passed away.
We have stated that all the "elements" come-to-be out of any one of them; and we have explained the manner in which their mutual conversion takes place. Let us nevertheless supplement our theory by the following speculations concerning them.
The same argument applies to all the "elements," proving that there is no single one of them out of which they all originate. But neither is there, beside these four, some other body from which they originate--a something intermediate, e.g. between Air and Water (coarser than Air, but finer than Water), or between Air and Fire (coarser than Fire, but finer than Air). For the supposed "intermediate" will be Air and Fire when a pair of contrasted qualities is added to it: but, since one of every two contrary qualities is a "privation," the "intermediate" never can exist--as some thinkers assert the "Boundless" or the "Environing" exists--in isolation. It is, therefore, equally and indifferently any one of the "elements," or else it is nothing.
Since, then, there is nothing--at least, nothing perceptible--prior to these, they must be all. That being so, either they must always persist and not be transformable into one another: or they must undergo transformation--either all of them, or some only (as Plato wrote in the Timaeus). Now it has been proved before that they must undergo reciprocal transformation. It has also been proved that the speed with which they come-to-be, one out of another, is not uniform--since the process of reciprocal transformation is relatively quick between the "elements" with a "complementary factor," but relatively slow between those which possess no such factor. Assuming, then, that the contrariety, in respect to which they are transformed, is one, the elements will inevitably be two: for it is "matter" that is the "mean" between the two contraries, and matter is imperceptible and inseparable from them. Since, however, the "elements" are seen to be more than two, the contrarieties must at the least be two. But the contrarieties being two, the "elements" must be four (as they evidently are) and cannot be three: for the couplings are four, since, though six are possible, the two in which the qualities are contrary to one another cannot occur.
These subjects have been discussed before: but the following arguments will make it clear that, since the "elements" are transformed into one another, it is impossible for any one of them--whether it be at the end or in the middle--to be an "originative source" of the rest. There can be no such "originative element" at the ends: for all of them would then be Fire or Earth, and this theory amounts to the assertion that all things are made of Fire or Earth. Nor can a "middle-element" be such an "originative source"--as some thinkers suppose that Air is transformed both into Fire and into Water, and Water both into Air and into Earth, while the "end-elements" are not further transformed into one another. For the process must come to a stop, and cannot continue ad infinitum in a straight line in either direction, since otherwise an infinite number of contrarieties would attach to the single "element." Let E stand for Earth, W for Water, A for Air, and F for Fire. Then (i) since A is transformed into F and W, there will be a contrariety belonging to A F. Let these contraries be whiteness and blackness. Again (ii) since A is transformed into W, there will be another contrariety: for W is not the same as F. Let this second contrariety be dryness and moistness, D being dryness and M moistness. Now if, when A is transformed into W, the "white" persists, Water will be moist and white: but if it does not persist, Water will be black since change is into contraries. Water, therefore, must be either white or black. Let it then be the first. On similar grounds, therefore, D (dryness) will also belong to F. Consequently F (Fire) as well as Air will be able to be transformed into Water: for it has qualities contrary to those of Water, since Fire was first taken to be black and then to be dry, while Water was moist and then showed itself white. Thus it is evident that all the "elements" will be able to be transformed out of one another; and that, in the instances we have taken, E (Earth) also will contain the remaining two "complementary factors," viz. the black and the moist (for these have not yet been coupled).
We have dealt with this last topic before the thesis we set out to prove. That thesis--viz. that the process cannot continue ad infinitum--will be clear from the following considerations. If Fire (which is represented by F) is not to revert, but is to be transformed in turn into some other "element" (e.g. into Q), a new contrariety, other than those mentioned, will belong to Fire and Q: for it has been assumed that Q is not the same as any of the four, E W A and F. Let K, then, belong to F and Y to Q. Then K will belong to all four, E W A and F: for they are transformed into one another. This last point, however, we may admit, has not yet been proved: but at any rate it is clear that if Q is to be transformed in turn into yet another "element," yet another contrariety will belong not only to Q but also to F (Fire). And, similarly, every addition of a new "element" will carry with it the attachment of a new contrariety to the preceding "elements." Consequently, if the "elements" are infinitely many, there will also belong to the single "element" an infinite number of contrarieties. But if that be so, it will be impossible to define any "element": impossible also for any to come-to-be. For if one is to result from another, it will have to pass through such a vast number of contrarieties--and indeed even more than any determinate number. Consequently (i) into some "elements" transformation will never be effected--viz. if the intermediates are infinite in number, as they must be if the "elements" are infinitely many: further (ii) there will not even be a transformation of Air into Fire, if the contrarieties are infinitely many: moreover (iii) all the "elements" become one. For all the contrarieties of the "elements" above F must belong to those below F, and vice versa: hence they will all be one.
What is the fundamental material which underlies the substances we can see and feel? What is its nature? Is there only one such primary material, or more than one? These are the questions to which Aristotle now turns.
Empedokles (or Empedocles, c.484-c.424 BCE) accounted for real change by positing that there must be more than one kind of matter: perceptible change is the result of essentially different materials coming together or falling apart in different proportions or arrangements. In particular, he believed in four elements: earth, air, fire, and water. Empedocles was a physician as well as a philosopher. One legend, elaborated by Matthew Arnold, holds that he ended his life by leaping into the crater of Sicily's Mt. Etna.
For Aristotle, the "elements" are not fundamental matter. He believes in the existence of a primary material which is a substrate for qualities ("contrarieties") such as cold and hot, but is inseparable from those qualities. Simple perceptible bodies ("elements") underlie complex perceptible bodies, but the substrate and its qualities underlie the elements. The elements themselves can be changed into one another, but not the qualities.
According to the translator, that other work is Aristotle's Physics, Book I, 6-9. He maintains that the primary matter and contrarieties are accurately defined there. I find there a discussion of contrarieties, but no clear definition of the primary matter. According to Mary Louise Gill, many scholars would not locate a discussion of the primary matter there. Indeed, Gill argues that Aristotle was not committed to a primary matter. [Gill 1989, p. 244] Traditional interpretations of Aristotle hold that he did believe in a primary matter, though, and point to this passage (in Generation and Corruption) as evidence.
The next section, then, will look for those sets of opposing qualities (contrarieties) by which the elements may be differentiated.
First Aristotle equates perceptible with tangible, which is objectionable because there are other modes of perception other than touch. Then he excludes from consideration qualities of perception other than touch. Speaking without any particular insight into Aristotelian dialectic or rhetorical subtleties, I can only regard this passage as unconvincing at best, illogical at worst.
Having narrowed the search to tangible qualities, Aristotle selects two pairs of qualities, the active qualities hot and cold, and the susceptible qualities moist and dry. Then he goes on to relate several other pairs of tangible qualities to moist and dry.
This chapter serves to illustrate the style of Aristotle's discourse. It is deductive (or attempts to be), drawing consequences from principles and definitions. Sometimes the principles are introduced just before they are invoked (as in introducing the principles that the elementary qualities must be active or passive just before using that principle to exclude heavy and light). This in itself makes the argument unconvincing to a modern reader, making it sound like the writer made up the principles as he went along. At least as important for the reader interested in scientific discourse, note that this discourse is general and abstract: there is no reference to empirical observations or even to generalizations from empirical observation.
Given four qualities, how many elements can be formed from two qualities inhering in a substrate? If no restrictions were placed on coupling the qualities, the answer would be six, for there are six ways to select two entities from a group of four. In practice, though, there are restrictions: an element cannot be both hot and cold, nor can one by both wet and dry. Rejecting these two combinations leaves four elements.
Thus the four elements are embodiments of pairs of qualities, as depiected below.
View a more artistic rendering of the four elements, from a manuscript by Bartholomeus Anglicus On the Properties of Things.
Some ancient Greek philosophers believed there was a single element, but Aristotle seems to say here that even if there existed a single primary matter, the forces which acted on it or the qualities which informed it would have to be plural--at least a pair of contrary qualities--to be able to give rise to observed differences. The substrate itself cannot be an element (simple body), for it cannot exist apart from its qualities; and if there are at least two qualities, there must be at least two combinations of qualities with the substrate.
Aristotle appears to be saying that the elements which are embodiments of qualities are not identical to the physical objects which go by the same name. For instance, the element air ("such-as-air," as the translator renders it) is not quite the same thing as the material one feels on a windy day.
This statement appears to be scientific in that it purports to be an explanation of a generalized observation. Forget, for a moment, that there really is no explanation in the statement. (How does the ice being a freezing of moist and cold "explain" the alleged fact that nothing comes to be from ice?) The observation which is supposedly explained was not arrived at by scientific means. No data lie behind it--certainly no controlled data.
No one of Aristotle's elements is more fundamental than another; indeed, they can be transformed one into another. They have irreducible differences but enough similarity to make transformation possible. The modern understanding of protons and neutrons in β radioactive decay is reminiscent of this kind of relationship. A proton is neither more nor less fundamental than a neutron, and a neutron does not "contain" a proton. Yet in β decay, a neutron is transformed into a proton, an electron , and an antineutrino.
The translation notes here: "Aristotle has shown that, by the conversion of a single quality in each case, Fire is transformed into Air, Air into Water, Water in to Earth, and Earth into Fire. This is a cycle of transformations. Moreover, the 'elements' have been taken in their natural consecutive series, according to their order in the Cosmos." The cycle, however, can begin with any of the four elements, and proceed either in the direction illustrated or in the opposite direction.
The beginning of this paragraph asserts that no elementary body results if one could simply remove an elementary quality from an element. For example, removing the dry from Fire leaves only the hot, which does not correspond to any one element. Later in the paragraph, when Aristotle says that the transformation of consecutive elements involves the passing-away of a single quality, he means the passing-away into its contrary quality; so in Fire, the passing-away of the dry into the moist would result in Air.
That is, there must be more than one element, for changes involving a single element are merely superficial changes (alteration); a single element is insufficient to explain more fundamental transformations (coming-to-be).
Even this paragraph, which at least mentions observation, is much more characteristic of a rationalistic argument than an empirical one. An empirical argument would dwell on what is observed and on the differences between what is observed and what is argued against (in this case, that fire is hot air). Instead, observation is merely mentioned, and what is observed is not even described. The most weighty argument presented is an unconvincing logical one purporting to show that the notion of fire as hot air leads to a contradiction.
The translator comments: "Perhaps, however, we ought to translate, 'for the supposed "intermediate" is nothing but "matter," and that is imperceptible and incapable of separate existence.'" That is, the prime matter or substratum mentioned above in Chapter 1, is not a separate element. One pair of contrary qualities inhabiting the prime matter would give rise to two elements; this is conceivable, but not "seen." Two pairs of qualities (inhabiting the same prime matter) would give rise to four elements, as discussed above in Chapter 3 and as "seen." (Aristotle again mentions observation, but he does not specify the observations with which a system of four elements is compatible and two incompatible.)
For our purposes, it is not as important to understand this argument in detail as to recognize that it is rationalistic. The tools of the argument are those of deductive logic (in this case argument by asserting that the opposite of the argument leads to a contradiction). The objects of the discourse seem to be abstract symbols rather than real physical entities. I do not wish to suggest that deductive, logical, and abstract discourse is not scientific; however, this discourse is disconnected from observed reality. It is unconvincing because its premises do not command assent.