A theoretical reflexion on some crucial concepts in functional morphology.

In this paper the author comments on some basic terms used in functional morphology, such as "form", "function", "biological role" and "optimum". A distinction between "function" and "action" is made. It is defended that causal morphology explains the form-parameters, while functional morphology helps to understand them. Because in our view understanding (answers to the question "why?") the form-parameters is the essence of functional morphology, the descriptive analysis of movements (which answers to "how?") is not the final purpose.