 Arguments against the thesis: The thesis is, in its present form, unprovable. The class of Turing Complete systems is open. It is defined on the basis of the existence of equivalence relations between known systems. In this sense it does not define the notion of computing intrinsically. It doesn’t not provide us with a philosophical theory that defines what computing exactly is. Consequently it does not allow us to exclude any system from the class a priori. At any time a proposal for a notion of computation might emerge that is fundamentally stronger. What is more, nature provides us with stronger notions of computing in the form of quantum computing. Quantum bits are really a generalization of the normal concept of bits that is associated with symbol manipulation, although in the end quantum computing does not seem to necessitate us to redefine the notion of computing so far. We can never rule out that research in physics, biology or chemistry will define systems that will force us to do so. Indeed various authors have suggested such systems but there is currently no consensus on convincing candidates (Davis 2006). Dershowitz and Gurevich (2008) claim to have vindicated the hypothesis, but this result is not generally accepted (see the discussion on “Computability – What would it mean to disprove the Church-Turing thesis”, in the  Other Internet Resources [OIR]).  