Abstract

Behavior and cognition, once conceived as psychological or interpersonal in origin, are increasingly thought to arise from biology. After investigating the validity of this trend of thinking, the article attempts to interpret what it means to the discipline of psychology. Two main categories of interpretation are discussed. First, this trend could mean that biological factors ultimately underlie traditionally psychological explanations i.e., biological factors are a sufficient condition for understanding behavior and cognition. Second, this trend could indicate that biological factors are important, and perhaps even traditionally overlooked, but are not sufficient in themselves to explain human behavior and cognition i.e., biological factors are necessary conditions among other necessary conditions. The practical and methodological implications of each of these two interpretations are clarified, with a special focus on relevant research limitations. We conclude that the evidence does not bear out a sufficiency thesis and, instead, supports more convincingly a necessity understanding of these trends.