ABSTRACT
As a matter of fact science introduces us to whole dimensions of reality which were previously unknown to human beings. This shows that reality-as-such and reality-as-known-by-us do not always coincide, and that a distinction between ontology and epistemology can and indeed must be made. Realism is certainly an unpopular stance today the standard arguments against it are by no means conclusive. In practical talk, a man's common sense means his good judgement, his freedom from excentricity. In philosophy it means something entirely different, it means his use of certain intellectual forms or categories of thought. Someone might object that these are only mental experiments, whose importance cannot be overestimated. However, mental experiments play a key role in both philosophy and science. No doubt they are merely hypothetical devices, but they also allow us to enter the dimension of possibility.
