That moves over into the filtering part of the TOE. A vision like function whether sight or heat or electromagnetic sense might well give one critter an advantage when run through the filter, but I still say the probability of something occurring initially is independent of the potential use.
Eyes might well develop even in a world without light.
I strongly disagree. Unless you're talking about the presence of light sensitive cells - the calling of which "eyes" is stretching a point - an eye requires iterative development and that development would not occur without a selective advantage. The same is true of all other complex systems.
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