Physics has long been taken as the paradigm science. This was particularly the case under the logical empiricists. Physics was the only science that was worth discussing in epistemology. This is no more true and modern philosophy of science has to take all disciplines into account. Yet, it’s true that biologists or sociologists don’t wonder whether the objects they study are real. Their philosophy is a spontaneous realism which, in their mind, is not questionable. Physicists are the rare scientists wondering if scientific theories are about the world or about themselves. Physics remains the only empirical science that brings real new insights into philosophy and that is able to influence our philosophical conception of the world. Thus, the results of physics can’t be ignored when discussing the status of reality or the validity of knowledge that science provides.