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NowAgnostic
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It seems the threads which get the most posts and views here are those related to evolution, with some side arguments about abiogenesis. Without wishing to go in depth yet another time, I just want to comment on a particular argument which seems superficially convincing at first, yet is fallacious. It interests me not because I have any particular interest in biology, but because I do have an interest in inductive reasoning, information theory, and the scientific/empirical method in general.
It is urged that it is highly unlikely that molecules would “spontaneously” arrange in the right way to form living material, or that complex structures would form by “random” mutation, or that the “right” combination of mutations (the vast majority of which are known to be deleterious) could occur to result in ever more complex life forms. Superficially, the argument seems meritorious. Counter-arguments involving natural selection are not to the point, because the necessary genetic diversity has to become existent in the first place. It looks like the fitness landscape is such that a hill-climbing mechanism (such as would be the case by single mutations) will not work.
So why is this argument fallacious? It stems from an improper understanding of what is meant by “probability”. I’ll first give an argument by way of analogy and then explain the theoretical basis.
Mr. X is violently attacked and shot. He is wheeled into the emergency room where the doctors find the bullet and remove it. Mr. X survives, as it is found the bullet just narrowly missed several vital organs which would have killed Mr. X had it hit them. In fact the trajectory of the bullet is found to be extremely, extremely unlikely. The angle of the gun, its caliber, etc., had to be just about precisely perfect; any slight deviation in angle or velocity would have killed Mr. X; the likelihood was astronomical, 10^-10, 10^-11, who knows. Mr. X’s relatives term his survival a “miracle”. But is this a real argument for supernatural intervention? Most would intuitively think not. Yet, the initial conditions for Mr. X’s survival were astronomically unlikely. So why do we think that these highly unlikely conditions were in fact the case rather than positing supernatural intervention?
Because in real life, “probability” is synonymous with quantifying our ignorance about something. That’s all it means. Prior to the gunshot, we would expect Mr. X to die, because we had limited knowledge about the initial conditions. After the gunshot, however, we infer the initial conditions were what they were, which we could have measured with the proper instruments. In other words, while P(Right Initial Conditions) is very small, P(Right Initial Conditions|Survival) is 1. Similar arguments apply regarding abiogenesis and mutations. With the right initial conditions or right combination of quantum events, the “right” chemical reactions or “right” mutations would occur. Arguing for the “improbability” of their occurrence is just as fallacious as arguing for the “improbability” of Mr. X’s survival; it’s arguing after the fact.
It is urged that it is highly unlikely that molecules would “spontaneously” arrange in the right way to form living material, or that complex structures would form by “random” mutation, or that the “right” combination of mutations (the vast majority of which are known to be deleterious) could occur to result in ever more complex life forms. Superficially, the argument seems meritorious. Counter-arguments involving natural selection are not to the point, because the necessary genetic diversity has to become existent in the first place. It looks like the fitness landscape is such that a hill-climbing mechanism (such as would be the case by single mutations) will not work.
So why is this argument fallacious? It stems from an improper understanding of what is meant by “probability”. I’ll first give an argument by way of analogy and then explain the theoretical basis.
Mr. X is violently attacked and shot. He is wheeled into the emergency room where the doctors find the bullet and remove it. Mr. X survives, as it is found the bullet just narrowly missed several vital organs which would have killed Mr. X had it hit them. In fact the trajectory of the bullet is found to be extremely, extremely unlikely. The angle of the gun, its caliber, etc., had to be just about precisely perfect; any slight deviation in angle or velocity would have killed Mr. X; the likelihood was astronomical, 10^-10, 10^-11, who knows. Mr. X’s relatives term his survival a “miracle”. But is this a real argument for supernatural intervention? Most would intuitively think not. Yet, the initial conditions for Mr. X’s survival were astronomically unlikely. So why do we think that these highly unlikely conditions were in fact the case rather than positing supernatural intervention?
Because in real life, “probability” is synonymous with quantifying our ignorance about something. That’s all it means. Prior to the gunshot, we would expect Mr. X to die, because we had limited knowledge about the initial conditions. After the gunshot, however, we infer the initial conditions were what they were, which we could have measured with the proper instruments. In other words, while P(Right Initial Conditions) is very small, P(Right Initial Conditions|Survival) is 1. Similar arguments apply regarding abiogenesis and mutations. With the right initial conditions or right combination of quantum events, the “right” chemical reactions or “right” mutations would occur. Arguing for the “improbability” of their occurrence is just as fallacious as arguing for the “improbability” of Mr. X’s survival; it’s arguing after the fact.
).
I have been having to explain that even to mathematicians…sheeesh!
