Summary

Theories are generalizations. The theoretical constructions used must explain what is true in common between particular examples, and must be suffciently detailed to explain what may be different between them, and how commonalities and differences may be resolved. Theories contain questions. For some theories the question(s) are explicit and represent what the theory is designed to explain. For others the questions are implicit and relate to the amount and type of generalization, given the particular choice of methods and examples used by researchers in constructing the theory. Theories continually change, as exceptions are found to their generalizations and as implicit questions about method and study options are exposed.

The development of a theory about vegetation and climate changes in central Alaska during the late Quaternary illustrates the following approaches: disconfirmation of a simple postulate, exploratory analysis in constructing new postulates, research to refine those postulates, and synthesis with knowledge from different types of investigation that give confirmatory support.

The use of a theory developed for one situation and applied to another requires particular care. Apractical example, in which a theory about mate selection in one species of fish provided the starting point for investigating other species, illustrates the need to specify axioms very carefully when using theories.

Theories may develop in a progressive or regressive way. Development is progressive if the generality of a theory increases. It may be regressive if the theory becomes unable to incorporate the conclusions from some investigations without its originator making ad hoc adjustments that invoke special exceptions for particular circumstances.

Introduction

We use theory when we analyze an ecological problem, no matter how practical or field oriented the problem may be.