One characteristic of social constructivism is that it rejects the role of superhuman necessity in either the invention/discovery of knowledge or its justification. In the field of invention it looks to contingency as playing an important part in the origin of knowledge, with historical interests and resourcing swaying the direction of mathematical and scientific knowledge growth. In the area of justification while acknowledging the role of logic and reason in testing, it also accepts that the criteria for acceptance vary and change over time. Thus mathematical proofs follow different standards in the present and throughout different periods in the past, as Paul Ernest argues.