Is evolution actually possible?

Discussion in 'Pseudoscience' started by gamelord, Sep 7, 2018.

  1. Kittamaru Never cruel nor cowardly... Staff Member

    Given the direction (or lack thereof) of this thread, I've shunted it over to Pseudoscience for the time being.
  2. Google AdSense Guest Advertisement

    to hide all adverts.
  3. James R Just this guy, you know? Staff Member

    I think that writing teleologically is mostly a convenience for biologists. It's a shorthand. The processes of evolution are well understood, and working biologists understand that genes (for example) do not have conscious goals.

    At one level, of course, it is quite reasonable to say that eyes are for seeing. Put more strictly, eyes tend to give an animal an survival advantage because they allow it to see. That advantage tends to increase the chances of reproductive success, which is all that genes ever really "care" about (and you'll note the incorrect teleological language there, too, no doubt).

    It is common to talk about genes for this or that. In practice, what is meant is that if you lack this or that gene, then you'll also most likely lack whatever it is that depends on the gene being there. Single genes rarely have just one function, and all genes work in tandem with the other genes. Then there are the epigenetic factors to consider, and so on and so forth.

    Why do animals have eyes? Ultimately, it is because the ability to sense light gave the animal's distant ancestors a survival advantage, so the trait was passed down through the generations. Over time, mutations and copying errors led to the development of the complex eyes we see today. In fact, it seems that eyes of one type or another have evolved completely independently over the course of evolutionary history.

    Take another example: the sickle-cell gene mutation. Why do some people have it? One answer is that it improves their resistance to malaria. So is the sickle-cell mutation a gene for malaria resistance, then? Did it evolve because human beings need malaria resistance? The technical answers are: no and no. Obviously there is no teleological reason a mutation occurs - it's random. Do giraffes develop long necks because they need them? No, that's silly.

    Natural selection works on natural variation in genes. Those variations that improve survivability and increase reproductive success, on average, tend to remain in the gene pool. Those that are harmful tend to be eliminated. Those that are neutral can go either way.

    The sickle-cell gene tends to make people more anemic, at the same time as protecting them (to some extent) from malaria. So should we talk about the gene as being a gene for malaria resistance, or for anemia? It seems like it's both. Why do some people have it? Answer: to make them anemic. Or: to make them more resistant to malaria. Or: just because it proved beneficial enough - and not too detrimental - to their ancestors that it was passed on to them.

    To give a similar example: I've been taken to task once or twice for talking about inanimate objects as if they were conscious. Specifically, I sometimes talk about atoms or electrons as "wanting" to do this or that - like "It wants to be in the lowest allowed energy state". Some people complain that I shouldn't talk that way, because an electron obviously doesn't "want" anything. But my talking that way doesn't mean that I lack the understanding that electrons aren't conscious little pixies. Rather, when I talk that way it's a convenient shorthand to describe what the electron is doing. If somebody follows up by asking why an electron would go to the lowest energy state, or whatever, then I am able to provide them with an appropriate description of the energy considerations, the relevant physical laws, and so on.

    Here's why such shorthand is useful: it allows us to examine processes at a higher level of abstraction, to concentrate on the novel or important features of the thing under consideration, rather than having to re-iterate well-understood and accepted foundational ideas every time we talk about something. If I say that a tossed ball wants to take the path that minimises the action, then unless I need to I don't have to go into what "action" is or why it is minimised. I can just concentrate on the problem at hand, namely the motion of the ball.
  4. Google AdSense Guest Advertisement

    to hide all adverts.
  5. Jeeves Valued Senior Member

    ^^What he said.
    Language predates scientific method; it's simply easier to communicate in the anthropomorphic metaphors and visual imagery of language as it already existed than to translate every concept into scientese every time you want to convey an idea, especially to laymen.
  6. Google AdSense Guest Advertisement

    to hide all adverts.
  7. Yazata Valued Senior Member

    Here's some excerpts from an introductory chapter by David Buller that outlines the problem of biological teleology much better than I could:

    It's from Function, Selection and Design, 1999 State University of New York Press

    When philosophers of science turned their attention to biology, one cluster of concepts stood out as particularly in need of explication --- the concept of function and its synonyms in order to, for the sake of, etc. For biologists routinely employ the concept of function and its relatives in their descriptions of the organs and traits of organisms: the function of the heart is to pump blood, the function of the kidneys is to filter metabolic wastes from the blood, the function of the thymus is to manufacture lymphocytes...

    Each of these descriptions of function cites an effect of an organ or trait, but not every effect of a trait or organ corresponds to a function of it. The heart, notoriously, makes noise in addition to pumping blood. But while all biologists would agree that pumping blood is a function of the heart, none would take making noise to be. ...

    Thus, "the function of X is to Y" cannot simply mean "X produces the effect Y", since this would fail to distinguish effects it is the function of a trait or organ to produce from those it is not its function to produce.

    This makes the biologist's concept of function particularly interesting to the philosopher of science; for it does not appear to be wholly explicable in terms of ordinary causation familiar from the physical sciences. David Hull (1974, p.102) put the matter very nicely:

    "Just as a physicist might say that heating a gas causes it to expand, a biologist might say that heating a mammal causes it to sweat. But a biologist might also say that a mammal sweats when heated in order to keep its temperature constant, while no physicist would say that a gas expands when heated in order to keep its temperature constant --- even though that is exactly what happens.

    What, then, are the theoretical commitments implicit in the biological concept of function that distinguish the case of the sweating mammal from that of the expanding gas? Why is constant temperature merely an effect of gas expansion while being the "function" of sweating in mammals? Explicating the biologist's concept of function in order to answer these questions is one of the problems for a philosopher of science interested in biology...

    An obvious way to think about the difference between the sweating mammal and the expanding gas is in terms of goals or purposes: sweating is in some sense "goal directed" or "purposive"...

    But, while we have a firm grasp of teleological processes in the behavioral arena (we know that it is for a person to act purposively or in a goal-directed manner), how can a process such as sweating be teleological (purposive or goal directed)? This question cuts to the heart of a long-standing philosophical problem. For ever since the scientific revolution, one of philosophy's foremost problems has been whether, and if so how, teleology is possible in nature. This problem has its roots in the conflict between Aristotelian metaphysics, which dominated philosophical thought before the scientific revolution of the 16th and 17th centuries, and the "corpuscularian" or "mechanical philosophy" that accompanied the scientific revolution.
    Last edited: Sep 14, 2018 at 5:56 PM
  8. James R Just this guy, you know? Staff Member


    That's interesting. Thanks. I have a few thoughts.

    If we ask why animals have a heart at all, it seems to me that the primary reason is that it provides a mechanism for the body to get oxygen to the organs and tissues. The existence of such a mechanism is an evolutionary advantage, primarily because it allows animals to grow larger. To compare, insects do not have hearts, and their maximum possible size is restricted as a result.

    In other words, I think it's fair to say that hearts only exist to pump blood around the body. If the body didn't/doesn't need to do that, then there is no need for a heart.

    This is not to say that evolution had any particular end goal in sight when the heart began to develop. It seems likely that in the early stages a slight advantage would have been available to those animals that could constrict blood vessels (or the equivalent) a little, via muscles or something like that. (I am not a biologist, and I'm sure an actual biologist would have a better idea about how the process probably started.) Over time, the muscles that helped blood flow developed in those animals for which they were beneficial, and eventually animals ended up with a more localised, single-purpose pump: the heart.

    Noise-making may well be an effect of the heart's operation, but it is at best a side-effect of what the heart is actually for. That is, we can't justify the evolution of the heart by appealing to an explanation involving noise-making, whereas we certainly can justify it in terms of pumping blood (see above).

    The same kind of argument applies to every major organ in the body: the kidneys, the thymus, the liver, the brain etc.

    Actually, the physics here is not quite right. Under ordinary circumstances, gases tend to expand at constant pressure, not constant temperature. Heating, of course, tends to increase temperature.

    I don't think the gas is a very good example about how physicists talk about these things, though. For an ideal gas, the most important variables are pressure, volume and temperature, and all three can vary depending on the particular process under consideration - sometimes simultaneously. Usually, one of the three variables is constrained by external factors, and the other two vary. Turn on the gas burner on your stove and the air above the burner increases in temperature and expands. In a sense, it does that because the surrounding air pressure remains approximately constant. I think an important distinction here is that the system under consideration (the air above the burner) is not self-regulating. It's state is determined in large part by its environment. On the other hand, an animal's body temperature is self-regulating. The body itself actively takes steps to try to keep the core temperature constant, regardless of changes to the external environment.

    I agree. But, as I said before, I think this is mostly a useful shorthand way of talking about a complex situation. If we start to ask questions like: how does the body start sweating or what triggers the sweating, then we inevitably move away from the idea of a "goal" of keeping the temperature constant.

Share This Page