We have seen that a number of absoiutist philosophies of mathematics have failed to establish the logical necessity of mathematical knowledge. Each of the three schools of thought logicism, formalism and intuitionism (the most clearly enunciated form of constructivism) attempts to provide a firm foundation for mathematical truth, by deriving it by mathematical proof from a restricted but secure realm of truth. In each case there is the laying down of a secure base of would-be absolute truth. For the logicists , formalists and intuitionists this consists of the axioms of logic, the intuitively certain principles of meta-mathematics, and the sell-evident axioms of ‘primordial intuition’, respectively. Each of these sets of axioms or principles is assumed without demonstration. Therefore each remains open to challenge, and thus to doubt. Subsequently each of the schools employs deductive logic to demonstrate the truth of the theorems of mathematics from their assumed bases. Consequently these three schools of thought fail to establish the absolute certainty of mathematical truth. For deductive logic only transmits truth, it does not inject it, and the conclusion of a logical proof is at best as certain as the weakest premise.