AbstractThe following considerations are not of a historical but of a systematic kind, i.e., without mentioning other historical theories, I would like to contribute my ideas on the problems of purpose in scientific thought.The first part concerns itself with the definition of science/knowledge. This will not involve a complete definition but only parts thereof, namely science/knowledge is a sort of theoretical acting which satisfies certain criteria and is therefore consciously or unconsciously always directed by aims and purposes.On the basis of this minimal definition, the relationship between aims and methods is described in the second part as a relationship between purpose and means: methods are more or less effective means for the realisation of certain aims. The third part contains some distinctions of the problems of purpose, which entail in particular the difference between aims intrinsic and extrinsic to science/knowledge and aims of action and nature.