Introduction or preface

According to Galileo the scientist is a philosopher of nature. But in the opinion of Galilei to study the nature the scientist must use mathematical truths and mathematical accuracy to know for certain, besides the scientist must verify theory by experiments. So scientific enterprise is in possession of two polarities: a theoretical constituent and an experimental constituent. Einstein thinks that scientific knowledge flows from the world of Lebenswelt thanks to new ideas by which we can construct a theory by a deductive reasoning. The experiment gives us the possibility to control theory, but this verification is always questionable. So for Galilei and Einstein science have a conceptual dimension by which we can trace the outline of an objective world.