4. Critical Reflections on the Theory of Place
There is no doubt that Aristotle's theory of place is a masterful conception, worthy of the genius that produced it. An obvious question, however, is whether it can still claim the allegiance of science, or whether present-day scientific understanding of place is utterly alien to Aristotle's view. Hence a few words of comparative evaluation are in order.
Certain points in Aristotle's theory are, admittedly, outmoded. For example, his principle of localization, the sphere of the fixed stars together with its immovable center, necessarily suffered the same fate as the astronomy of which it was an integral part. Also, his ideas on the natural movement of the elements would seem to be in need of considerable remaking, if indeed they can be salvaged at all. But does this mean that his whole theory of place has to be discarded? The answer depends on whether the essentials are retainable. Two points in particular have to be considered.
a) There is first his very concept of place. Aristotle defines place as a container. Modern science usually defines it as a point in a system of coordinates. Place, in this view, depends on whatever system of coordinates is devised to serve one's scientific purpose, and it is much more something imposed by the investigator than something given by nature.
Doubtless, this idea of place, which is more mathematical than Aristotle's, does lend itself better to the modern proclivity for measuring things on a mathematical scale; but it does not necessarily invalidate Aristotle's container concept, which is more concrete and, for want of a better term, more natural, that is, more in line with what place appears to be in ordinary, prescientific experience. The man on the street may not know what a point in a system of coordinates is, but he does know that things are in a place, which is the meaning of place as a container. Furthermore, an interesting comparison could be made between the modern notion of fields of force or gravity and Aristotle's idea that place has powers of attraction. All in all, the theory of place as container or enveloping surface should still have meaning even for the scientist. Revisions there must be to bring it up to date, but these will not destroy the basic concept.
b) The second point is more difficult to resolve. Along with the ancients Aristotle believed that there was in the universe an absolute system of localization. If this is true, at least some motions are absolute, and not just relative. The moderns in general dispute this idea. Motion, it is widely thought, is always relative to certain frames of reference arbitrarily chosen. It takes place within two terms, but the terms and hence the motion have meaning only in reference to other similarly arbitrary terms. The question is not whether some motion is relative, but whether any other is possible.
Who is right in this debate we are not prepared to say. A fair question, however, is whether absolute relativity - ironical locution! - of place and motion can be conceived by the mind ( to utter a phrase is not necessarily to conceive it); or, same question, whether the fluctuations (relative changes) of place and motion in the universe do not imply a stable (absolute) principle of localization and measurement. At any event, and this is where we shall leave the matter, scientific thought itself has not achieved unanimity on this head. The debate goes on.12
5. Theory of the Void13
As we mentioned at the beginning of our discussion on place, the theory of the void and the theory of place are related questions, aspects of the same basic problem. Some of the ancients thought that motion presupposes place; others believed that motion is possible only in a void, meaning a place in which there is nothing - an empty space. The Atomists in particular had recourse to the void to explain the motion of the atoms. Modern theories of force and motion (dynamics) speak in much the same vein. The partisans of the void recognized two kinds. One was the void that existed independently of bodies; this was thought necessary for local motion. The other was the interstitial void, or the void of interstices, to account for condensation and rarefaction. After discussing the meaning of the void and the opinions of others," Aristotle declares his own position, arguing first the nonexistence of the separate void," then the nonexistence of the interstitial void." On the supposition of a void, he explains, motion is unintelligible. Why? Because in a void there is no distinction of up and down, hence no way of positioning a body and tracing its motion. Besides, what is there to prevent local motion even in the absence of gaps between bodies, as may be seen in the circular motion of a liquid? Here, it seems, Aristotle advances the theory of motion by circular displacement, or vortex motion, a theory that Descartes was to develop and make famous. In fine, the void, says Aristotle, is inconceivable, and so far from being necessary for motion, it would render motion impossible.
The void, or vacuum, was destined however to have its career. Aristotelians continued, understandably, to oppose it, taking as axiomatic that "nature abhors a vacuum." But with the beginning of modern science the notion of a vacuum came again into its own, the consequence in large measure of the experiments of Torricelli (16o8-1647), an early Italian physicist popularly regarded as the first man to create a vacuum. In France the question ignited a celebrated controversy that pitted against each other such notables as Pascal (1623-1662), defender of the vacuum, and Descartes (1596-164o), championing in this instance the Aristotelians, upholders of the plenum.
We have no intention of handing down a verdict on this controversy. But we will say that both sides had everything to gain by distinguishing between the relative vacuum which the physicist may achieve in his laboratory, and the theoretically absolute or metaphysical vacuum whose defense, or denunciation, turns on philosophical suppositions. And the distinction that should then have been made, should still be made whenever there is question of the void or vacuum.
6. Space
In modern scientific thought the problem of place has been mostly translated into the closely allied problem of space. Consequently, motion, as said before, is no longer conceived as a change of place or container but as a relational variation in a system of coordinates projected in space. Hence, a modern scientist prefers to speak of bodies being in space rather than in place. Yet these two perspectives are not wholly divergent; and while Aristotle does not set forth a theory of space, it is possible to find points of comparison between his idea of place and the modern notion of space. So, what is space from an Aristotelian standpoint?
To the imagination, space is very nearly like an enormous void, a vast continuum in which all bodies are located. But this is not a very scientific description. A more precise characterization of space is to say that it is comprised of dimensions, or an order of dimensions, necessarily conceived as continuous. From this it is a natural step to determine and delimit space by pivotal points within an assumed system of coordinates, thus giving explicit and, usually, mathematical expression to the implicit dimensions of space.
But this is an empirical, or utilitarian, concept of space. It leaves unanswered the philosophical problem as to its objective reality. The questions that the philosopher asks are these: Is space, as appears to the unsophisticated view, an objective reality, independent of perception? Or is it only a subjective condition of perception? Or, third possibility, is it something between, partly subjective and partly objective? To pose these questions is to suggest the three major philosophical theories of space, which are:
a) Space is an absolute (i.e., wholly objective) reality.
This notion is expressed in
- the void of the ancient Atomists,
- the extended substance of Descartes, and
- the geometric substance of Newton.
b) Space is a construct of the mind. Prime specimens of this theory are
- Leibnitz' order of coexistences, and
- Kant's a priori form of sensibility.
c) Space is an abstraction grounded in reality.17
Of these answers, the last is by all odds the correct one; it is also the one that best accords with the general character of Aristotelian philosophy. Space, by this account, denotes the real order of dimensions in or between bodies, but this is all it denotes. Everything else, every other property of bodies, is omitted from the concept of space. Primarily a logical and mathematical entity, it is nevertheless based on a concrete reality, namely, dimensive quantity or the extension of bodies, and this is a real accident, one of the ten predicaments. Thus, the reality of space, such as it is, rests on the reality of concrete extension, of which it expresses the dimensional or measurable aspect, prescinded from all actual or specified limits. Considered from the standpoint of indeterminateness, space exists only in the mind but corresponds to, because derived from, an objective reality, the reality of concrete extension.
Space, in consequence, is a more abstract concept than place. A logical entity with a foundation in things, space is so to speak one remove from reality, whereas place is itself a reality, a real accident of things. If, from one point of view, space is abstract, limitless extension, place, the limit of what contains, is comprised of concrete, limited (and limiting) dimensions; and furthermore, in Aristotelian thought, it possesses a real, a physical power of attraction.
Space, on the other hand, indicates something prior to all considerations of force and energy (dynamics). It is therefore not only more abstract but also emptier of denotation, denoting much less than place; and one of the reasons why the sciences prefer to think of bodies in space rather than in place is just this greater simplicity or lack of denotation.18