Abstract

What chemists take as molecular structure is a theoretical construct based on the concepts of chemical bond, atoms in molecules, etc. and hence it should be distinguished from tangible structures around us. The practical adequacy of it has been demonstrated by the established method of retro-synthetic analysis, for instance. But it is not derived a priori from quantum mechanical treatments of the molecule and criticized for being irrelevant to the reality of the molecule. There is persistent skepticism about it. The present study aims to overcome this skepticism by having recourse to the concepts of affordance and phenomenal field. The basic idea of our approach is suggested by the following statement of Niels Bohr: ‘evidence obtained under different experimental conditions cannot be comprehended within a single picture but must be regarded as complementary in the sense that only the totality of the phenomena exhausts the possible information about the objects’. This implies that we should take account of a context in which the cognition of a fact arises when we think about human activities including science. This can be realized by invoking affordances of a complex such as {agent, devices, methods, substances, surroundings}. That is to say, affordances are context-relative dispositional attributes of {agent-material world} complexes as is asserted by Harré and Llored. The phenomenal field is a conceptual device which schematizes the contextual aspect of affordance and, more importantly, serves as a link between the concept of affordance and Kant’s theory of knowledge, by which alone affordances are realized as the dispositional properties of {agent-material world} complexes. Because affordances become actualized in various phenomenal fields, affordances of one and the same object may well be distinct from one another. In conclusion we can take that molecular structure is the affordance of a complex that includes a chemist who is engaged in organic synthesis, whereas a quantum mechanical picture of the molecule may be one of the possible affordances of a complex that includes a quantum chemist who cares about electronic states of the molecule.