among these methods are phylogenetic, ontogenetic, and cross-cultural
comparisons. Such comparisons allow more naturalistic perspectives on
behavior and greater generality of empirical findings. They serve to augment
the power and utility of psychological investigation as well as to enlarge the
scope of the discipline. In fact, they may be deemed necessary to a full
understanding of psychology.

Psychology is concerned, broadly, with describing, explaining, and
predicting mental processes and behavior in humans and other animals in a
wide variety of environmental contexts. Man is the reference point in this
psychological nexus. Phylogenetic, ontogenetic, and cultural comparisons
are principal in psychology because together they encompass the scope of
substantive thinking and empirical study of man's mental processes and
behavior in the widest variety of contexts. A phylogenetic perspective is
necessary in psychology to assess species capabilities, to evaluate similarities
and differences among species, and to ascertain the nature of psychological
adaptations. An ontogenetic perspective is necessary to ascertain how man's
psychology changes or maintains over the life cycle. A cultural perspective is
necessary to ascertain how adaptable and plastic or inflexible and fixed
human psychology is. (Additionally, experimental design and statistics
underpin valid comparisons, allow for their verification, and circumscribe
their interpretation.) Thus, each comparative perspective contributes
invaluable description to the corpus of psychology, and each contributes
uniquely to the overall analytical goals of psychology, viz. explanation and
prediction.

These principal comparisons do not always stand alone. In practice, animal
behavior and cross-cultural comparativists frequently invoke or employ a
developmental perspective. Animal-behavior developmental and cross-
cultural developmental perspectives derive from the principal comparative
methods but are not secondary to them. Indeed, vis-à-vis the goals of
psychology, these derivative comparisons may play a more significant role
than do the principal comparisons; for in combining phylogenetic or cultural
perspectives with developmental ones, the scope of these comparisons and
their implications for psychology are inevitably enlarged and rendered more
complete.

Psychological comparisons among species, ages, or peoples, although
different in substance and subject populations, nevertheless share certain
assumptions, philosophies, methodological issues, and goals. As a

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