SCIENTIFIC REALISM AND QUANTUM PHYSICS

Summary of Priest G., “Primary Qualities Are Secondary Qualities Too”, British Journal for Philosophy of Science, Vol. 40, (1989), pp. 29-37.

1.0 Introduction

In the paper, the author is comparing the current conflict between quantum physics and scientific realism with the scientific revolution of the 17^th century. According to the author, quantum physics is indicating a change in the 17^th century scientific conception of matter. By doing so he is arguing that such a change in the conception of matter will lead to a realistic interpretation of quantum mechanics.

2.0 Primary and Secondary Qualities

The mechanistic conception of matter which was formed by the work of primarily Galileo and Descartes, characterizes matter by its extension and locatability in space and time. These are what are called primary properties. Matter would have these properties even if there is no conscious observer present. But some properties of matter like color, smell etc. will not be present without the presence of conscious observer. Such properties are called secondary properties and they arise because of the interaction between an observer and the object.

With the advent of atomic and wave theories, it was possible to show that the dispositions which lead to the rise of secondary properties where really aggregate primary properties of micro-structure of matter.

According to the author, similar kind of revision in the conception of matter is indicated by quantum mechanics. In quantum mechanics, some properties like the coefficients of the eigenstates are observer-independent and hence such prperties are analougous to the primary properties of the mechanistic conception of matter. Whereas, some properties like spin which are primary in the mechanistic conception are observer-dependent and such properties are analougous to the secondary properties of the mechanistic conception.

3.0 EPR

EPR argument brings out the strongest objection to realism. According to realism, the happenings at one place cannot affect the happenings at other places instantaneously, whereas, EPR seems to say the opposite.

The author argues that the problem arises when the idea that there are two particles (in context of EPR) interacting in space-time is forced on to the situation. In fact, there is no problem for realism if we accept that Ψ state is what describes reality and thus there are no to particles out there.