Hedonism, egoism, and human motivational architecture

I challenge psychological hedonism and psychological egoism, the theses that apparently altruistic actions are instead always motivated by desires for pleasure or other self-interested goals as ultimate ends. My challenge is based on a model of human motivational architecture that has received substantial quantities of support in the recent cognitive neuroscience literature. The model divides motivational architecture into two distinct systems. The function of the reward/instrumental system is learning; it is responsible for identifying which states of affairs predict, on the condition that certain action sequences are undertaken, the receipt of rewarding outcomes. The function of the hedonic system is representational. Pleasure functions to signal that rewarding states of affairs are in fact being realized.

If this model is correct, then this has ramifications for psychological hedonism and egoism. First, psychological hedonism is unlikely to be true because it contradicts the distinct functional roles assigned to pleasure and reward; the model says pleasure has a representational function, while psychological hedonism says it has a reward function. Psychological egoism is unlikely to be true because this theory makes predictions about neural activation patterns in the brain structures that implement the model's two systems. These predictions are not supported by the neuroscientific evidence.