Suppose Hitler won the war. Furthermore, there were certain nonAryans who had a mutation such that everything they saw was tinted green and caused a harsh pain. Let ‘G’ denote this new property of their eyes. Hitler enjoyed this suffering, so he allowed these nonAryans to survive. After a few generations, nonAryans with eyes like ours died out, and the nonAryans with these mutated eyes continued to survive. This mutation spread throughout the population.
Consider one such creature, m. Plantinga asks, “But wouldn’t it be wrong (not to mention crazy) to say that m’s visual system is functioning properly? Or that its function is to produce both pain and a visual field that is uniformly green? Or that the resistance medical technicians who desperately try to repair the damage are interfering with the proper function of the visual system?” (p. 26) This example seems to work against any evolutionary theory of proper function.
Here’s one worry for this example.
On an evolutionary theory of proper function, m’s eyes would not be functioning properly when producing G according to an earlier design plan. For thousands of years, humans evolved in such a way that being able to see clearly (the actual colors of objects and without pain) contributed to their survival. Let “S” denote the property of “seeing real colors easily and uninhibitedly (i.e., without pain)”. A function of the eye, because of evolution, is to exhibit S. And G interferes with an eye’s successfully exhibiting S.
So this point should at least explain why it is intuitive that m’s eyes are malfunctioning. They are not functioning properly according to their previous design plan.
But Plantinga could press that it’s also odd to think that m’s eyes are functioning properly. It’s weird to think that the function of m’s eyes, according to this new design plan, is to produce G.
But it’s not too crazy. If I pinch my arm, I feel pain. It’s the function of many mechanisms in my body to produce this pain. The evolutionist will say that this function arose because having mechanisms which produced this pain helped my ancestors to survive.
And is it crazy to say this same thing for a creature whose eyes exhibited G? Call this creature S. For S’s ancestors, any time they were about to be killed by Nazis, they saw that the creature exhibited G, and so they avoided them. The mutation which produced G helped these creatures to survive. If we waited enough generations, it seems intuitive that m’s eyes are supposed to produce G. If a Nazi were about to corner S, and S’s eyes suddenly stopped producing G, S might think, “oh crap! my eyes are supposed to be producing G! What’s going on?” So Plantinga’s Hitler case doesn’t successfully refute evolutionary theories of proper function.
(I used S instead of m in this example, because by the time m exists, the Nazis would no longer be hunting people because the mutation would’ve spread into their population as well.)
(I’m thinking of turning these ideas into a paper, so please pay the proper respects. However, you guys might have such forceful objections to my ideas that I will no longer want to turn it into a paper. We’ll see!)