I have observed numerous examples of otherwise intelligent and rationale people whose brains are perfectly capable of accepting ideas and concepts that are demonstrably irrational. My understanding of evolution is that characteristics and traits which provide an evolutionary advantage are retained while those which provide a disadvantage are ultimately discarded. To me that means, at some time, being able to accept the irrational was an evolutionary advantage to our species and that is why it has survived in the human brain. Does anyone have any idea what that advantage could have possibly been?

Through most of our evolutionary history, the speed of making a decision has been at least as important as correctness. Rationality is expensive and until recently (in an evolutionary time frame), we haven't had the luxury of that time for very many decisions.

Pascal Boyer, in his book "Religion Explained," argues that religion is, in part, based on a false (and expedient) decision that certain events are due to a conscious actor. It boils down to the evolutionary cost of certain types of errors. For example, the rustling in the bushes. There's an evolutionary advantage to making this mistake over making the opposite mistake. In that case, the lion caused the rustle and the mistake meant that you didn't pass on your genes. If you were wrong the other way (concluding it was a lion when it was really the wind), you had a few seconds of fear, but got to live to pass on your genes.

Thanks Mr. Baker. I knew there had to be a rational reason for so much irrationality.

However, it appears we will be dealing with religious irrationality for a few million more years until the tide turns and correctness becomes more important than speed in making decisions. How discouraging.