Since you can say "Why? Elan vital!" to any possible observation, it is equally good at explaining all outcomes, a disguised hypothesis of maximum entropy, etcetera.

But you say earlier 'Elan vital' was greatly weakened by a piece of evidence

Heh. A fair point! Every mysterianism, though it may fail to predict details and quantities, is ultimately vulnerable to the one experience in all the world that it does prohibit - the discovery of a non-mysterious explanation.

Could it not also have been partly due to earlier scientists underestimating the degree to which qualitative phenomena derive from quantitative phenomena? Their error, then, was in tending to assume this quality was immune to study, rather than in assuming the quality itself.

Since you can say "Why? Elan vital!" to any possible observation, it is equally good at explaining all outcomes, a disguised hypothesis of maximum entropy, etcetera.

But you say earlier 'Elan vital' was greatly weakened by a piece of evidence. In that light, it's hypothesis could be stated "the mechanisms of living processes are of a different kind than the mechanisms of non-living processes, so you will not be able to study them with chemistry". This is false, but I don't think it's entirely worthless as a hypothesis, since biochemistry is noticeably different from non-living chemistry.

I think 'elan vital' makes some sense, even in a modern light. Most of the reactions in our body would not occur without enzymes, and enzymes are a characteristic feature of life. So perhaps we can say that 'elan vital' is enzymes! There is at least one experiment I can think of that could have been interpreted to show this too: I believe it involved fermentation being carried out with yeast-water (no living yeast, but clearly having their enzymes).

People with the benefit of hindsight failing to realize how reasonable vitalism sounded at the time is precisely why they go ahead and propose similar explanations for consciousness, which seems far more mysterious to them than biology, hence legitimately in need of a mysterious explanation. Vitalists were merely stupid, to make such a big deal out of such an ordinary-seeming phenomenon as biology - consciousness is different.

This is precisely one of the ways in which I went astray when I was still a diligent practitioner of mere Traditional Rationality, rather than Bayescraft. The reason to consider how reasonable mistakes seemed without benefit of hindsight, is not to excuse them, because this is to fail to learn from them. The reason to consider how reasonable it seemed is to realize that not everything that sounds reasonable is a good idea; you've got to be strict about things like yielding increases in predictive power.

My mother's husband professes to believe that our actions have no control over the way in which we die, but that "if you're meant to die in a plane crash and avoid flying, then a plane will end up crashing into you!" for example.

After explaining how I would expect that belief to constrain experience (like how it would affect plane crash statistics), as well as showing that he himself was demonstrating his unbelief every time he went to see a doctor, he told me that you "just can't apply numbers to this," and "Well, you shouldn't tempt fate."

My question to the LW community is this: How do you avoid kicking people in the nuts all of the time?

And to continue the thread of Roy's comment as picked up by Eliezer, it might have been a fairly reasonable conjecture at the time (or at some earlier time). We have to be wary about hindsight bias. Imagine a time before biochemistry and before evolution theory. The only physicalist "explanations" you've ever heard of or thought of for why animals exist and how they function are obvious non-starters...

You think to yourself, "the folks who are tempted by such explanations just don't realize how far away they are from really explaining this stuff; they are deluded." And invoking an elan vital, while clearly not providing a complete explanation, at least creates a placeholder. Perhaps it might be possible to discover different versions of the elan vital; perhaps we could discover how this force interacts with other non-material substances such as ancestor spirits, consciousness, magic, demons, angels etc. Perhaps there could be a whole science of the psychic and the occult, or maybe a new branch of theological inquiry that would illuminate these issues. Maybe those faraway wisemen that we've heard about know something about these matters that we don't know. Or maybe the human mind is simply not equipped to understand these inner workings of the world, and we have to pray instead for illumination. In the afterlife, perhaps, it will all be clear. Either way, that guy who thinks he will discover the mysteries of the soul by dissecting the pineal gland seem curiously obtuse in not appreciating the magnitude of the mystery.

Now, in retrospect we know what worked and what didn't. But the mystics, it seems, could have turned out to have been right, and it is not obvious that they were irrational to favor the mystic hypothesis given the evidence available to them at the time.

Perhaps what we should be looking for is not structural problems intrinsic to certain kinds of questions and answers, but rather attitude problems that occur, for example, when ask questions without really caring about finding the answer, or when we use mysterious answers to lullaby our curiosity prematurely.

Nitpick:

The Secret of Life was infinitely beyond the reach of science! Not just a little beyond, mind you, but infinitely beyond!

But Kelvin (in your quote) qualified it with "... hitherto entered on". Whether or not "infinitely" is fitting, doesn't this imply that Kelvin did not think that future scientific inquiry could not succeed?

I think Kelvin gets a bit of a raw deal in the way people often quote him: "[life etc.] is infinitely beyond the range of any scientific inquiry".

By cutting off the quote there it sounds like he is claiming that science will never be able to understand life. However, as you show above, he continues with, "... hitherto entered on." Thus, the sentence is making a claim about the power of science up to the time of his writing to understand life. This is a far more reasonable claim.

Desiring a mysterious explantion is like wanting to be in a room with no people inside. Once you explain it it's not mysterious any more. The property depends on your actions: emptyness is destroyed by you entering, mysticism is destroyed by you explaining it. Just an alternative to the map-territory way of putting it

Am I the only one who, while reading this post, thought “why doesn’t the same apply to anything else we ever discover”?

Elan vital (and phlogiston and luminiferous aether etc.) were particles/substances/phenomena postulated to try to explain observations made. How are quarks, electrons and photons any different? Just because we recognise these as the best available theory today, I am not sure I understand how one is a curiosity-stopper any more than the other.

The real curiosity-stopper is the suggestion that something is forever beyond our understanding and that attempting to research it is destined to be futile. Your quote from Lord Kelvin exhibits this mentality, but only very slightly. Certainly a lot less than some of that stuff you hear from religious people who think God explains everything but is beyond our understanding. I think the history of science shows that this mentality is continually diminishing, and Lord Kelvin’s quote may simply be a transitional fossil.

I still see traces of this mentality today. Ask a cosmologist what happened in the first few seconds after the big bang and they might say the particle horizon makes it fundamentally impossible to see beyond the point where the universe became optically transparent. I think many people think similarly about consciousness — not because they think we can’t dissect the brain and figure out how it works, but rather because they think we will never be able to come up wtih a coherent, useful definition of the term that reasonably matches our intuition. I think each of these are curiosity-stoppers.

The influence of animal or vegetable life on matter is infinitely beyond the range of any scientific inquiry hitherto entered on. Its power of directing the motions of moving particles, in the demonstrated daily miracle of our human free-will, and in the growth of generation after generation of plants from a single seed, are infinitely different from any possible result of the fortuitous concurrence of atoms... Modern biologists were coming once more to the acceptance of something and that was a vital principle.

Given what we know now about the vastly complex and highly improbable processes and structures of organisms -- what we have learned since Lord Kelvin about nucleic acids, proteins, evolution, embryology, and so on -- and given that there are many mysteries still, such as consciousness and aging, or how to cure or prevent viruses, cancers, or heart disease, for which we still have far too few clues -- this rather metaphorical and poetic view of Lord Kelvin's is certainly a far more accurate view of the organism, for the time, than any alternative model that posited that the many details and functions of human body, or its origins, could be most accurately modeled by simple equations like those used for Newtonian physics. To the extent vitalism detered biologists from such idiocy vitalism must be considered for its time a triumph. Too bad there were to few similarly good metaphors to deter people from believing in central economic planning or Marx's "Laws of History."

Admittedly, the "infinetely different" part is hyperbole, but "vastly different" would have turned out to be fairly accurate.

Eliezer: It doesn't seem to me that you really engaged with Nick's point here. Also, I have pointed out to you before that there were lots of philosophers who believed that consciousness was unique and mysterious but life was not long before science rejected vitalism.

Your hand is just... stuff... and for some reason it moves under your direction. Is this not magic?

Yeah, I think it is. The one model we start with is the model of ourselves. Our hand moves because we will it to do so. If that were the only model I had, that's how I'd interpret the universe - every event was the result of the will of some being.

And stopping at "The Wizard Did It" makes perfect sense. We experience our own decisions as sufficient causes for our own actions.

I wonder how long it took for the concept of mechanism to take hold.

These are the signs of mysterious answers to mysterious questions: Anothe good sign is that the mysterious answer is always in retreat. Suddenly, people explain some phenonmena, previously thought to be explainable only by "elan vitale" or "god" or "the influence of platonic Ideals". And the mysterious answer retreats to a smaller realm. And that realm just keeps on shrinking...

My summary: A mysterious answer is a fake explanation that acts as a semantic stop sign. Signs for mysterious answers:

• Explanation acts as curiousity-stopper rather than anticipation-controller

• Hypothesis is a black box (no underlying principles to derive from)

• Social indication that people cherish their ignorance