Is the Copenhagen interpretation really a subjective one? What is the special role that observations play in quantum theory? Is there really something peculiar about the projection postulate? Why does the Copenhagenist treat probabilities as properties of individual systems? Is there a measurement problem, and if so, can itin principle be solved within the framework of quantum theory? We offer aconceptual treatment of the Copenhagen interpretation of quantum mechanics in which these questions are answered and contrast it with another interpretation (...) which we call Popperism. The interpretations differ in their choice of a state description, from which it follows that they will offer a different account of the relation of measurements to states and different ways of describing quantum theory. But the two descriptions are equally consistent and physically completely equivalent. (shrink)

Some aspects of the problem of measurement in quantum theory are treated. We stress that the problem is both physical and conceptual, that the physical problem has been solved and the conceptual one is inherent in quantum theory. We also deal with some remarks made by Wigner concerning physics and the explanation of life, and present alternative positions on the mind-matter relationship within a deterministic framework, as we see them.