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This is mostly a question about usage.

There is a probability-related idea that has been used in at least two biological contexts. The idea is that if something happened, it was probably likely to do so.

This has been used in discussions about evolution, in which it is said that while we have trouble imagining circumstances in which self-replicating forms arise, the odds were probably in favor of their emergence when it actually occurred. And in discussions of the existence of intelligent life--it may be prevalent if we make the somewhat natural assumption (among others) that our own emergence was not highly improbable, given the existence of a suitable planet and so on.

Is there a name for this principle? I am familiar with the idea in the context of probability but have thought of it as an 'argument from likelihood' in biology. Also if there is a good description of the idea in a biological context a reference would be appreciated.

The tag is a little arbitrary. Thanks for any suggestions.

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conditional probability? – Memming May 4 '14 at 17:25
@memming: Almost, except that it's a fallacy. To say that condition X existed because if it did then conditional probability would give a simple explanation for Y is backwards. So the idea is related. – daniel May 4 '14 at 22:14
up vote 2 down vote accepted

It may also be called as Idea of maximum parsimony. It is used in phylogenetics to construct phylogenetic trees which require the least number of evolutionary events.

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Max. parsimony is essentially Occam's razor. Maybe that's the best we can do. – daniel Apr 18 '14 at 15:51
@daniel Yes. I just wanted to give a specific example – biogirl Apr 18 '14 at 16:15
@memming's comment above is also right. Occam's razor would work if we could assume anything about initial conditions. Then conditional probability gives the simplest explanation. – daniel May 10 '14 at 15:05

The principle of least effort / path of least resistance fit pretty well: animals, people, and systems (like evolution or a mechanical system like a machine) will naturally choose the path of least resistance or effort. The principal applies to chemistry (low energy states) and physics (the path an electrical current takes) as well. Occam's Razor fits somewhat too in an abstract sense in that nature favors simple solutions over complex ones. You may find something in thermodynamics as well.

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