The present book is intended for people interested in fundamental epistemological questions. Science is here defined as a continuous endeavour which attempts to embrace all that may be included as part of our phenomenological world including both our .inner" and .outer" worlds, with the intention of extending, describing, explaining, and understanding the phenomena by finding lawful relations among them, so that we may predict and control them. Prerequisites are that a) the phenomena studied may be considered inter-subjective, and b) the scientific investi.gation does not violate ethical norms. This definition of science is based on Hume's epistemological presumptions and hence is in sharp opposition to the presently still dominating physicalistic and behavi.ouristic epistemological premises. This domination is surprising since there appears to be no substantial support whatsoever for their basic presumptions. Indeed, their premises apparently are a consequence of a serious misunderstanding of the term .objectivity".