Life-Span Developmental Psychology: Methodological Contributions

ships, such as cause-effect and mediational chain, are in the theoretical domain of science rather than the methodological domain ( Rychlak, 1976a), that is, they are cognized rather than observed. Only spatial and temporal relations among facts can be observed directly; other relations must be based on theoretical analysis, via either deduction from a hierarchical theory or consistency with a concatenated theory. A theoretical analysis is not a blind activity, but rather is guided by a goal, the attainment of which is the criterion for success of the analysis. Stated another way, the point is that in the phrase "interrelated facts," interrelated is the past participle of "interrelate" as a transitive verb; and facts are interrelated by someone for some purpose. Observations in science are also products of goal-directed activities, even when the purpose is only "I wonder what would happen if . . ." Progress in science is success in satisfying these purposes, or purposes that arise serendipitously from these purposes.

Serendipity can occur in observations or in interpretations, that is, in the methodological domain or in the theoretical domain; but in either case, it occurs in the context of discovery and does not become scientific knowledge until it has been formalized in the context of justification, which involves theoretical analysis -- purposeful activity. The contexts of discovery and justification are unified in the concept of scientific activity; but they remain distinct because their purposes are different and their "logics" are different. The context of discovery includes reasons for entertaining an hypothesis, as Kaplan ( 1964) said, and the context of justification includes reasons for accepting an hypothesis. The "logic" of discovery is psychological or sociological; that of justification is formal logic or dialectical logic. "Rational reconstruction" can encompass the latter, but "empirical reconstruction" is needed for the former.

Any given instance of scientific activity involves a concrete purpose, namely, solving a specific empirical problem by means of practice, which can be experimentation or application, or solving a specific theoretical problem by means of interpretation, or theoretical analysis. The general purpose that covers these concrete specific purposes can be characterized as problem solving ( Laudan, 1977), or more precisely as practice in the service of theoretical analysis and theoretical analysis in the service of practice. These different general purposes are united in the practice-theory dialectic, which, as it is instantiated in science, is: Theory without practice is empty, and practice without theory is blind.

Agassi J. ( 1964). "The nature of scientific problems and their roots in metaphysics". In M. Bunge (Ed.), The critical approach to science and philosophy: In honor of Karl R. Popper (pp. 189-211). London: Free Press of Glencoe (Collier-Macmillan).

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