The presumptions are, however, easily rebutted. Such presumptions determine who bears the onus of proof. Even epidemiology is maturing to heed the severe difficulties with presumptions about causality. Both of these presumptions required clear and convincing evidence overcome. Section 76 of the Act introduces two conclusive presumptions. He also pointed out the limitations of their presumptions and methodology. Certain presumptions are made in a theoretical Roberval balance. He saw that its metaphysical presumptions necessarily led to this ethical dead end. Contrary to the long-standing presumptions, climate change poses 'negligible' threat to minnows' reproduction. On the applicable presumptions, see "Moloi v Minister for Justice and Constitutional Affairs". A number of presumptions are found in most common law jurisdictions. How general the following presumptions were is unclear. This framework of presumptions is termed the Theory of the Real. The South African courts, however, did not apply these presumptions. None of these presumptions may be made safely.