Qualitative change from quantitative change: mathematical catastrophe theory in relation to psychoanalysis

The relation of qualitative change to quantitative change is important to psychoanalytic theory. Until recently no tools were available for dealing with the problem, but the development of catastrophe theory has provided methods for studying it. Psychoanalytic investigators might benefit from the methods of catastrophe theory, and dilemmas arising from the supposed impossibility of relating quantity to quality are seen to allow of solution.