Evolution and chance

In the contemporary theory of evolution, three classical meanings of the notion of chance come into play : the ordinary meaning of chance, the probabilistic notion of randomness, and the epistemological notion of contingency with reference to a theoretical system. These three notions are sufficient in order to define the status of chance on the principal levels of the evolutive process where fortuitous effects are commonly invoked: imitations, genetic deviations. genetic revolutions, ecological changes, macroevolution. The question is raised finally, whether the diverse meanings of chance considered in the present study may be brought to one, and whether they refer to a subjective (or "epistemic')form of chance or to an objective chance.