[michaelscott]

Note that even with Seldon's predictions, a requirement for their fulfilment was that the predictions not be made public so that they would not be altered. The difference in economics and psychology, unlike in chemistry or astronomy, is that these fields are self-reflective. They have an "awareness" of themselves as disciplines and can change and act on information of themselves to in turn gain new "awareness" and behaviour.

Economics is even worse, as it does hold to some fundamental aspects of finite resource allocation and supply/demand in addition to the self-reflectance. This means its model is probably some hybrid of physics-like fundamentals and the weird self-awareness of the "soft science" disciplines.