The pleasure principle (PP) may be a verifiable fundamental law of the living matter in the universe, and this law might then be used for forecasting human self-evolution. I do not pretend to “prove” PP, but argue that it must be regarded as a scientific hypothesis. Accordingly, I formulate verifiable and falsifiable postulates of PP. Their confirmation would allow the construction of a new scientific discipline, hedodynamics, that would be able to forecast the future development of human civilization and even the probable structure and psychology of other rational beings within the universe. I suggest basic hedodynamical scenarios for human (posthuman) civilization and argue that the discovery of the neural correlate of pleasure would provide more detailed forecasts. In particular, I demonstrate how the studies of pleasure mechanisms might predict the degree of aggression in future societies. I conclude that PP may become a scientific basis for fundamental, not phenomenological (based on extrapolations), future forecasting on large timescales.