I share your feeling that such behavior is, in some sense, unwise or erroneous, but this does not mean that it does not occur,' Amos wrote to an American economist who complained about the description of human nature implied by 'Value Theory.' 'A theory of vision cannot be faulted for predicting optical illusions. Similarly, a descriptive theory of choice cannot be rejected on the grounds that it predicts 'irrational behavior' if the behavior in question is in fact observed.