 The actual arguments using these methods introduce no new logical phenomena as such—weak and strong counterexamples can also be given by other means. For the moment, we refer to the literature for further details: Brouwer 1949A, 1949B, 1954F; Heyting 1956: 117–120; Myhill 1966; Dummett 2000: 244–245; van Atten 2018. But we do note here one particular aspect of this method. It seems to introduce a further notion of negation, by accepting that, if it is known that the creating subject will never prove \(A\), then \(A\) is false. But this is actually no different from the notion of negation as impossibility. Heuristically, this can be seen as follows: given the freedom the creating subject has to construct whatever it can, the only way to show that there can be no moment at which the subject demonstrates \(A\) is to show that a demonstration of \(A\) itself is impossible. An actual justification of the principle is this: If the creating subject demonstrates a proposition \(A\), it does so at a particular moment \(n\); so, by contraposition, if it is contradictory that there exists a moment \(n\) at which the subject demonstrates \(A\), then \(A\) is  contradictory.[11]