How Well Understood is Motion?

How Well Understood is Motion?

Not very. It seems to be generally assumed that we have motion under intellectual control, even if once it was quite a mystery. Physics has tamed it. Consciousness is still untamed, it is agreed, but motion is a bright spot in our understanding of nature. But I think the truth is that we have stopped worrying about what we don’t understand about motion; we just accept the gaps in our knowledge as inevitable. We are de facto motion mysterians. I don’t believe the debate about the relativity or absoluteness of motion was ever satisfactorily resolved; instead, a general positivism has been invoked. So, this basic question about motion remains unsettled. But do we have adequate predictive theories about motion—do we know the laws of motion? We must distinguish three natural kinds of motion: inanimate motion, animate motion, and intelligent motion. By the first I mean the kind of motion studied by Galileo and Newton—what is sometimes called “impressed motion”: bodies moving through space under the influence of a force–planets, projectiles, whole galaxies. Here the problem is that we don’t really understand gravity (and the same goes for the so-called electromagnetic force): for we don’t know the mechanism of gravity. It acts over space but apparently without employing any sort of medium or intelligible machinery. If you depress the gas pedal in your car, a mechanism is activated that converts this into a means of acceleration—what we call an engine. If there were no such engine, but just empty space, we would be rightly baffled—how could the pedal alone have such momentous effects? But that’s exactly what happens with gravity—massive effects but no mediating mechanism, just empty space. Hence the postulation of an ether to act as some sort of vaporous mechanism. This is an old story that I will not belabor. It is as pressing and baffling now as it ever was (despite Einstein’s invocation of “curved space” and such curiosities). And why should matter give rise to this force (ditto the electromagnetic force)? It just seems pasted on, superadded (like icing on a cake). What have extension, solidity, and mass got to do with an attractive force? Couldn’t matter exist and give rise to no such force? Isn’t this at least conceivable? Evidently, gravity exists, whatever it is exactly, but we don’t know how it comes to exist (rather like consciousness, in fact). So, we don’t know how massive bodies produce motion in other bodies, often separated by great distances. We know the laws, but we don’t know the means (as Newton notoriously admitted). And what is a force anyway? It isn’t matter but it isn’t empty space either, but something in between—invisible, impalpable, ghostly. No wonder some physicists (e.g., Hertz) have tried to dispense with forces—they just aren’t physical. But all motion is supposed to depend on them. We are hardly swimming in a sea of transparency here; we are wallowing in a murky pool of obscurity. But we have wallowed in it long enough not to notice anymore. And all this is before we get to the puzzles of quantum theory, in which the very idea of a moving object comes into question, along with its position in space. Inanimate motion is thus not a safe space for intellectual comprehension, despite the scientific advances of the last few centuries. In point of fact, we don’t really know why or how the universe moves at all, as opposed to sitting still all the time; it just does, powered by forces that seem inexplicable. You could be forgiven for supposing that motion is just one giant mystery at the heart of the universe (the position of our intellectual ancestors).

Then we have the motion of organisms. These motions are not even recognized in physical theories of inanimate motion; they go beyond anything that existed before life evolved (straight lines, ellipses). They are naturally conceived as self-generated not impressed from outside; they are functional, goal-directed. This applies even to plants and single-celled organisms. Such motions appear emergent, not prefigured in the simple motions of planets and projectiles. They have internal causes of some sort, but we don’t really have a science of how these causes lead to the motions we observe: we don’t have laws of animate motion comparable to the laws of inanimate motion. There is no Principia Biologica to be set beside Newton’s great book. There are no mathematical equations of organic motion. Still less do we have a science of intelligent motion—rational, deliberate, creative motion. The motions involved in language use, say, do not follow from Newton’s laws of motion—or not in any way we can use. The mind produces motion, but not in the way material bodies do. We call this type of motion “behavior” to distinguish it from inanimate motion, thereby acknowledging a difference of natural kind—motion under the force of intelligence, so to speak. You can’t predict the motion of human bodies from Newton’s laws, though they apply to the particles that compose human bodies; rational creative motion is an emergent type of motion. It has no precursor in the inanimate world; it calls for its own mode of understanding—the kind we call psychological. If the laws of behavior could be subsumed under the laws of physics, psychology would be a lot easier—but, notoriously, they are not. Therefore, the motions of life-forms are not reducible to the motions of falling bodies, planets, etc.

What I have said so far is familiar enough (and familiarly disputed), but what I am about to say ought to strike you as bizarre, because I want to ask whether they are any analogues of the laws of motion in the case of the mind. Are there any highly general laws of nature that govern both material motions and mental “motions”? I am thinking primarily of Newton’s three laws of motion: does the mind follow laws that resemble these laws without being examples of them? If so, Newton’s laws could be seen as special cases of more general laws. The law of inertia is the easiest to generalize to the mind: just as a moving body will continue moving uniformly unless subjected to an outside force, so the mind will continue in its present condition unless affected by an outside influence. The mind doesn’t spontaneously change of its own accord but as a result of impinging causes. Nature stays the same unless caused to change; it doesn’t change of its own volition. A mountain will stay a mountain unless acted on from outside, and a mind will stay the same mind unless caused to deviate from its present state. Things don’t change for no reason—they are naturally inert. It is not, say, in the very nature of a belief to change over time without anything making it change. The mind changes only because it is forced to change not because it feels like changing. Left to its own devices, nature is lazy, stuck in its ways. But what about Newton’s second law—that force equals mass times acceleration? On the face of it no such analogue is possible, because the mind is not a moving object to begin with. The brain moves through space and may accelerate or decelerate; it may strike another object and exert a force on it (you could use brains as projectiles). It also contains motions of chemicals and electrical impulses. But minds don’t fly about the place, hitting other objects, causing damage; motion is alien to their nature (except derivatively on the body and brain). True, but they may have properties like motion as it features in the second law—they may have similar types of effect, exert forces of an analogous kind. Consider problem-solving. Think of this as a power of the mind: the ability to solve problems, practical and theoretical. It is analogous to a physical force. Are there, then, analogues of mass and acceleration? Mass is quantity of matter, so isn’t there such a thing as quantity of mind—largeness, capaciousness? The brain certainly admits of such description, and its dimensions correspond to degrees of intelligence and sophistication; don’t some animals have larger minds than others? The bigger the mind, the better it is at problem-solving; the greater the mental mass, the greater the mental force exerted on a problem (say, how to achieve a desired end). But that isn’t all: there is also the amount of mental activity and the speed of such activity. Some individuals and species are quicker of mind than others; they solve problems more quickly. We can then say that larger quicker minds exert more problem-solving force—as more massive faster projectiles exert more impact force.[1] If the mind were an immaterial substance, we could say that the quantity of mental stuff, along with its internal activity, contributes to (determines) its problem-solving capacity. Or again, the bigger and faster the brain, the more mental force it can exert. The mind doesn’t move through physical space, but it does something analogous—it cuts through intellectual space. In brief, mental force equals mental size (“mass”) times mental quickness (“velocity”). Generalizing, we have the following law: power equals quantity times activity. Intuitively, the more stuff there is of a certain kind and the more active (lively) it is, the more it can do. Big active things do more than small inactive things. Suns can do more than planets gravity-wise, and geniuses can do more than the average man problem-solving-wise. Impact is a function of size and activity-level. You can’t do much if you are small and inert, like a speck of dust; but you can do a lot if you are large and energetic, like a star or a human brain. Accordingly, there is a general principle (I won’t say law) that covers matter and mind—things that move and things that don’t move. Likewise, hot objects (including fires) can have more impact (do more harm) than cold objects, especially if they are large. Otherwise put, big energetic things have greater impact than small low-energy things—and that includes big energetic minds. This makes Newton’s second law an instance of a more general principle. It doesn’t make gravitational phenomena any more intelligible, but it does suggest a more general content to the law; indeed, it gives it something like an a priori status. As to Newton’s third law, I don’t see any clear analogue in the case of the mind—what kind of mental reaction would follow every action of mind? That law has no a priori component that I can discern and seems limited to the case of physical impact.

Does anything else in nature literally move apart from material bodies? And do we understand such motion? Space doesn’t move, unless we decide to reduce it to systems of bodies. Does time move? It doesn’t move through time, though we do speak of it in metaphors of movement—as if it has a forward momentum and a direction. Clocks move and are easily confused with time itself. Do fields of force move? Apparently not, though they may be propagated through space. Numbers don’t move (try pushing the number 2 aside). Does music move? We do speak of musical “movements” and music is connected to dance. Lawyers make motions, as do debaters. There are social movements. A person may move (“jump”) from one subject to another, or be “immovable” and “stuck in his ways”. A philosopher may make argumentative “moves”. Locutions of motion are common and natural. This doesn’t mean we understand motion very well, or at all; it merely means that we know it exists (like consciousness). The whole topic of movement strikes me as conceptually underexplored. Zeno went so far as to deny its existence, on conceptual grounds; he found motion paradoxical not merely poorly understood. The concept itself is far from clear, as witness the debate between absolutists and relativists. It is taken very much for granted. It seems to me quite puzzling and problematic: what is it exactly, where does it come from, what is its explanation, from whence does our knowledge of it derive (the senses or the intellect)? The concept of matter is by no means straightforward, and neither is the concept of space; but these enter into our concept of motion, along with force and time. We really have quite a superficial grasp of the nature of motion. We have a practical grasp of motion, as do other animals, which suffices for evolutionary purposes; but from a theoretical point of view, we are pretty much in the dark (Newton threw only a partial light on the subject).[2]

[1] You might wonder whether mental quickness and mental size are independent variables, as velocity and mass are. The brain is certainly a place of both size and quickness; indeed, a big brain is ipso facto slower just in virtue of the fact that it takes longer for a nerve impulse to traverse a large brain than a small one (say, an elephant brain versus an ant brain). Bird brains seem extremely quick but are not large. I think it is perfectly conceivable that a mind should have a large capacity but be relatively slow moving (I believe I have known people like that). Likewise, a mind could be quick but narrow in scope. Psychological quickness and size are not invariably correlated.

[2] There is an irony in this because motion is often trumpeted as one of science’s great triumphs—and so it is, up to a point. But not all mysteries and puzzles have been dispelled, as the thinkers of the renaissance recognized. Motion is still intellectually challenging, if not defeating. Positivism is just a way of sweeping the problems under the rug. Philosophers, in particular, should not regard it as a paradigm of transparency. It is closer to consciousness than we tend to suppose.