Abstract
Since Aristotle, many scientists take the notion of Nature/Physicallaws as primary. The "psychological truth", if that exists, would be sort of secondary and emerging truth. I will explain in a non technical way the main result I have got at IRIDIA, which shows that IF we assume the digital version of Descartes Mechanist thesis in the cognitive sciences, THEN the physical sciences are *necessarily* derivable from pure mathematical computer science without any physical ontological commitment. I will sketch an easy non constructive proof explaining only the *necessity* of that reduction, and then I will explain, without going through much details, how the easy non constructive proof has been made constructive and how this has led to an explicit derivation of a part of physics. By comparing the physics derived from computer science with the empirical physics, the mechanist hypothesis has been made confirmable/falsifiable, and thus has been made "scientific" in the sense of Popper. Actually a non trivial quantum logic, quite close to the empirical quantum logic, has already been derived, confirming (not proving, of course) the digital mechanist hypothesis in the cognitive science.
Keywords
Universal Turing Machines, Theoretical computer science, GodelLob selfreference logic, quantum logic
References

Bruno Marchal. (2005)
Theoretical computer science and natural sciences,
Physics of Life Reviews, .
Accepted for publication.