Final answer:
The instinct theory of motivation has been criticized for merely labeling behaviors without explaining them, as opposed to drive-reduction and arousal theories, which provide mechanisms for understanding behavior.
Step-by-step explanation:
The theory that has been accused of simply naming rather than explaining behaviors is instinct theory of motivation. This theory, as proposed by William James, suggests that behavior is driven by instincts, which are species-specific patterns of behavior that are unlearned. However, the theory has faced criticism because it often just labels the behaviors without providing a deep explanation for why such behaviors exist or how they develop. In contrast to instinct theory, other motivational theories such as drive-reduction theory and arousal theory offer mechanisms that describe how deviations from homeostasis can create physiological needs, which result in psychological drives that direct behavior.