 Arguments in favor of the thesis: The theory of Turing machines seems to be the most general theory possible that we can formulate since it is based on a very limited set of assumptions about what computing is. The fact that it is universal also points in the direction of its generality. It is difficult to conceive in what sense a more powerful system could be “more” universal. Even if we could think of such a more powerful system, the in- and output for such a system would have to be finite and discrete and the computation time also finite. So, in the end, any computation would have the form of a finite function between finite data sets, and, in principle, all such relations can be modeled on Turing machines. The fact that all known systems of computation we have defined so far have the same power also corroborates the thesis. 