the telemetrists began to use a computer to program the computer that designed the program for the computer that programmed the robot-controlling com… - Isaac Asimov

You might as well ask why the same man sprints safely across an obstacle course in the day, and falls over the furniture in his room at night.

Are there Laws of Humanics as there are Laws of Robotics? How many Laws of Humanics might there be and how can they be expressed mathematically? I don't know. "Perhaps, though, there may come a day when someone will work out the Laws of Humanics and then be able to predict the broad strokes of the future, and know what might be in store for humanity, instead of merely guessing as I do, and know what to do to make things better, instead of merely speculating. I dream sometimes of founding a mathematical science which I think of as 'psychohistory,' but I know I can't and I fear no one ever will.

The two known axioms deal with human beings, and they are based on the unspoken axiom that human beings are the only intelligent species in the Galaxy, and therefore the only organisms whose actions are significant in the development of society and history. That is the unstated axiom: that there is only one species of intelligence in the Galaxy and that it is Homo sapiens. If there were 'something new,' if there were other species of intelligence widely different in nature, then their behavior would not be described accurately by the mathematics of psychohistory and Seldon's Plan would have no meaning. Do you see?