The Evolutionary Contingency Thesis: Do Biological Laws Exist?

We discussed this topic today in our philosophy of science club, and I’m curious what people here would think.

Josh has said the following regarding rules in biology:

Contrast this with what philosopher John Beatty proposed in this paper, called the Evolutionary Contingency Thesis:

All generalizations about the living world:
a) are just mathematical, physical, or chemical generalizations (or deductive consequences of mathematical, physical, or chemical generalizations plus initial conditions), or
b) are distinctively biological, in which case they describe contingent outcomes of evolution.

Mehmet Elgin recasts the thesis as a clearer argument:

  1. All distinctively biological generalizations describe contingent outcomes of
  2. Laws are supposed to be more than just contingently true.
  3. Therefore, distinctively biological generalizations are not laws.

Thus, unlike physics or chemistry, since all biological life that we study arise from contingent evolutionary processes (which would not repeat if rewound the same way), then biologists are not really studying universal laws like Newton’s Law of Gravitation. Instead, they are merely studying generalizations that happen to be true for a very specific set of conditions, and are likely not very applicable to the rest of biology.

Unlike Josh, who seems to still have confidence in rules despite the few exceptions, I have been told by a biologist friend that almost nothing a biologist finds is applicable outside of the narrow domain in which it was found in the first place. The example she gave was Mendelian genetics: supposedly, we used to think that Mendelian genetics held true for all organisms with genes. However, we then discovered many examples of non-Mendelian inheritance, to the point that one cannot deduce any law which says “If an organism has traits X, Y, Z then it will follow Mendelian genetics.” Instead, one can only say that “an organism is Mendelian if we examine it and it happens to be actually Mendelian.”

One might bring up natural selection as an example of a law in biology. However, as Josh and other biologists have repeatedly emphasized, natural selection is far from being the only dominant force in evolution. Secondly, in domains where it holds, natural selection seems to not really be a distinctly biological law but merely a tautological mathematical statement with little actual content: organisms which are more fit will reproduce more.

Note that this is deeper than merely a naive statement that “biology is more complex than physics, so it’s hard to find generalizable laws” - instead, it’s a statement that you shouldn’t expect biology to have any universal applicability, since the processes that produce life are contingent in the first place.



I quote the time bomb in your discussion.

Buried inside the idea that evolutionary processes are not repeatable is the implication that that some things are truly random. I di not find this position to be the usual part of a Christian worldview.

Well, as as far as we know it’s only “truly random” from a scientific perspective, as we’ve discussed in several threads here. As a Christian one would tend to believe that God is expressing His will somehow in that randomness and contingency. And there could be deeper, yet-undiscovered actual more universal laws in biology (contrary to the Evolutionary Contingency Thesis) that make the biological world less random.

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Please forgive me… i dont want to be uncomfortably exact… but i just cant let the phrase “only truly random from a scientific perspecrive” stand without a comment:

If you had left out the amplifying term “truly”… since you are going to “de-emphasize” with “from a scientific perspective”… i wouldnt have even twitched. Well, maybe a little.

I assume that sentence is equal to:

“As far as we know it only appears random, like rolling dice appears random…”


“As far as we believe, nothing is truly random from a theological perspective …”

I think another way to ask the question raised by the OP would be to ask what must life be like on other planets? Must it involve reproduction, must it involve copying of genetic memory, must clades be monophyletic, etc.


How would you describe the following propositions?

  1. All organisms are cells, or are made up of cells.

  2. All organisms have other organisms as parents.

  3. All organisms exist out of equilibrium with their environments.

In other words, can you name any exceptions to these statements? Observed exceptions, that is – not hypothetical.

I’m writing this from O’Hare airport, about to board a plane for Pittsburgh, so I may not be able to follow up for a while. But the questions you raise with this OP are exceedingly interesting.


The problem with “contingency” is not that it occurs. Of course it does.

The problem is disciplining the notion so that it does not bleed our theories white of their content. Example: “Well, we didn’t expect to observe that, given theory Y, but then – it’s contingency again! Theory Y is still true, as long as we allow for some noise and contingency around the edges.”

And notice what is never threatened by the existence of contingency (which means, basically, any damn thing can happen and does): evolution itself.

So it’s better to not have even a hypothesis, much less a theory, while fooling laypeople into thinking you have both?

Do real scientists not actively investigate the noise, while you and your colleagues deal entirely in rhetoric?


Not a biologist, but I’ll take a stab at this.

Two replies: First, how about viruses?
Second, sure, you could define viruses as not an organism or not alive, but viruses seem to be different from rocks or other clearly non-living organisms. This would then just be a tautological statement, devoid of significant empirical content.

OK, I can grant you this as a “biological law”.

By equilibrium, do you mean thermodynamic equilibrium? Then that would not be a distinctively biological generalization, as Beatty puts it, but a result of physical or chemical laws.

I don’t think this is relevant to my OP, which assumes that evolution happens. You can understand it as more of a working out of the implications of that assumption.

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OK, sure, take the “truly” out.

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Viruses are a great example. So are prions. They are at the boundary point. Yes, they do require other cells on which to subsist, but many cellular parasites also require cells on which to subsist (see malaria).

False. Everyone agrees that at some point the chain of ancestry terminates, either by special creation or abiogenesis. So at least one organism does not have parents.

Moreover, many (numerically most?) organisms do not have parents (plural) but only have a single parent (singular), because they do not reproduce sexually.

It also appears that fossils exist in equilibrium with their environment, or at least very near equilibrium. They aren’t organisms? Well, they are dead organisms, are they not? Though the appeal to physical law here is appropriate.

@Pnelson, I encourage you to use emoji’s to denote jokes like this. Some people get confused and think you are being serious.

@dga471, nothing here assumes evolution. Nor is contingency the only reason for the exception. That is merely one reason, and there are others.

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But if we suppose that the living world conforms to decipherable laws, beyond those of physics and chemistry alone, though not in violation of them, then we have to work out those laws.

  • Norman A. Johnson