It has always been the ideal of science to discover laws of nature on which we can all agree. Agreement requires evidence independent of individual judgment, i.e., objective evidence. We apply the term objective to such unbiased scientific evidence because we associate it with an external world of objects that we conceive to be the origin of our information. This external world is instinctively invented by each of us as a means of dealing with invariant patterns in his private world of experience. The invention is validated and elaborated as a consequence of the fact that it turns out to be sharable. In fact the common content of all our invented external worlds is so unambiguous and independent of individual bias that it can form the universally accepted basis for communication and action in an organized society. The consistency of the patterns of experience associated with the external world is such that we are under severe psychological compulsion to assign to this world an existence independent of our experience and a reality superior to that of any small part of our experience. Physical science is devoted to the study of the “laws” of the external physical universe, i.e., to the behaviour of the objects in it. Hence there is a strong tendency to project into the external world the information gathered by scientifically objective methods and even the theoretical concepts in terms of which the information is interpreted. Whatever is so projected is objective in a second sense of the term, i.e., assigned by us to the external world of objects.