7. Biologists and ecologists misuse some very basic terms

In his well-known paper Ecological laws: what would they be and why would they matter, Marc Lange gives us an example of these issues when he surveys some very familiar ground:

Recently, there has been considerable discussion of whether ecology seeks laws, whether it has already found some, and whether there are any ecological laws to be found. In many of these discussions, the authors defend their favorite candidates for ecological lawhood (Lange, 2005).

Lange also tackles the common argument against the possible existence of biological and ecological laws. As he puts it: “other authors argue that ecological phenomena are too complex and locally variable, temporally and spatially, to be covered by general ecological laws” (Lange, 2005). But he then goes on to make the same assumption that Murray made above, and that all other commentators also immediately make: that biologists and ecologists are in fact very accurate in what they are talking about; and that biologists and ecologists speak of eco-biological matters with great clarity and rigour. So therefore, and as Lange expresses it, if there are no laws, then something must be intrinsically wrong or questionable—perhaps even to the point of irrelevance—with lawhood:

Before working our way toward the concept of an ecological law, we must back up to explain the general concept of a law of nature. (Lange, 2005, p. 395).

But it is actually not so clear that even such simple things as volume or the distinction and relationship between mass and inertia have been properly grasped within this discipline.

When Turchin, cited above, proposes his own candidate selection of relevant laws, his first is “Exponential growth—the first law of population dynamics”, about which he then more fully says:

Let us compare it to something about which there is no argument that it is a law—Newton’s First Law, or the law of inertia. The similarity between the exponential law and the law of inertia is striking. First, both statements specify the state of the system in the absence of any “influences” acting on it. The law of inertia says how a body will move in the absence of forces exerted on it; exponential law specifies how a population will grow/decline in the absence of systematic changes in the environmental factors influencing reproduction and mortality. (Turchin, 2001, p. 17).

But … does a similarity in fact exist? If one does, then it cannot be in the way Turchin suggests. As a first issue, Newton not only tells us about inertia, he goes on to show how mass is an exemplar. He proves its status by giving us force and the inverse square law, and he specifies how magnitudes link them to acceleration—his famous F = ma—so showing how the whole thing works. We can then see it in operation in inclined planes, and in tricky questions about air resistance. Turchin fails to give examples of such forces. Nor does he say what the relevant ‘accelerations’ are, and he therefore gives no real indication of the prevailing inertia. To propose that a population is already ‘accelerating’ exponentially and therefore a specific acceleration is not necessary is simply to repeat the definition of its given steady state. If any change from that exponentiating steady state is indeed to be described as an ‘acceleration’, then that should surely have been clearly stated and delineated. The matter of how to derive a value for the population’s inertia should then also be properly clarified, for Newtonian mass is the magnitude of inertia or resistance to having a given state changed. The two cannot be separated. How do we determine, from Turchin’s proposed law, a population’s inertia if changed away from exponential growth? Does that proposed commodity, whatever it might be, truly behave as mass does? And then what would be the analogue of inclined planes and air resistance?

Another important way in which Turchin’s claim fails is when he again juxtaposes the proposed exponential law with Newton’s law of inertia and says:

… neither statement can be subjected to a direct empirical test. Just as we cannot observe a body on which no forces are acting, we cannot observe a population growing exponentially (at least, not for long), because we cannot indefinitely keep its environment stationary. (Turchin, 2001, p. 18).

This comparison completely misses the point.

Turchin makes a later claim for comparability, but it does not improve the case:

In fact, the exponential law is most profitably thought of as the null state in which any population would be if no forces (= environmental changes) were acting on it. It is a direct equivalent of the law of inertia, and is used in the same way, as a starting point to which all kinds of complications are added. (Turchin, 2001, p. 19).

Newton does not just add ‘complications’. He rather takes us from Kepler’s laws to the explanation of tides, the moon’s orbit, pendulum swings, and inclined planes. That is the power of mass and inertia—F = ma—and that is what those words imply. Newton’s is certainly a very broad agenda, but if comparisons are going to be made then it is surely reasonable to point to the difference in scale of achievement. It is therefore difficult to see how these two juxtaposed laws are anywhere close to being comparable.

We are not questioning that exponential growth could be a law for ecology. But to compare it to Newton’s is surely misplaced due to a confusion of terms. There is no real basis for the claim of structural comparability. Biological organisms certainly suffer constraints, but those constraints have nothing to do with Newton’s law as here described … except in so far as Newton’s law perhaps governs their molecular behaviour. The famous second law of thermodynamics results from that microscopic Newtonian behaviour … but it is still an avowedly Newtonian behaviour. So it is possible that the second law is instead the source of the constraint to which Turchin alludes for biological organisms, and not the exponential law to which he directs our attention. We shall turn to the questions of volumes and molecules shortly.