Why True Beliefs Are Adaptive
I thought I should tighten up one of the arguments put in my previous post with an actual example based on one given by Plantinga.
Let's examine the behaviour of running away from tigers. Here is what Plantinga says:
Perhaps Paul very much likes the idea of being eaten, but when he sees a tiger, always runs off looking for a better prospect, because he thinks it unlikely the tiger he sees will eat him. This will get his body parts in the right place so far as survival is concerned, without involving much by way of true belief... Or perhaps he thinks the tiger is a large, friendly, cuddly pussycat and wants to pet it; but he also believes that the best way to pet it is to run away from it... Clearly there are any number of belief-cum-desire systems that equally fit a given bit of behaviour.
[Plantinga, Alvin Warrant and Proper Function, (New York: Oxford University Press), 1993]
These beliefs about tigers work when there is a possibility of running away from one. But suppose Paul is stuck in a cave with a tiger. Which belief will make him more likely to survive - (1) I like being eaten, but I want something better than this specimen, (2) I want to pet the tiger but the best way is run away or (3) tigers are dangerous?
Neither (1) or (2) work, because being stuck in a confined space with the tiger, Paul may well decide to compromise and go with the being eaten, or petting this specimen. Unless of course, yet more beliefs are added: (1a) I don't like being eaten by tigers in caves, or (2a) Tigers in caves don't react well to being petted.
So, the problem for adaptive false beliefs is that they aren't versatile. Indeed, Plantinga's arguments based on probability can be used against him: What are the chances of an new adaptive false belief spontaneously appearing just in time to deal with a new circumstance not deal with by the rather specialised original false beliefs?
There is so much less work for the brain to do, and so much more likelihood of survival if Paul has the true belief (3) tigers are dangerous. And that is why true beliefs are generally (though not always) more adaptive than false beliefs.
So next time someone mentions Plantinga's argument, I suggest the response "but what about tigers in caves?"