For reinforcing a perilous social psychological imperialism toward other behavioral sciences and for suggesting that humans are naturally oriented toward others, the strong interpretation of Aristotle's famous aphorism needs to be retired. Certainly sociality is a dominant force that shapes thought, behavior, physiology, and neural activity. However, enthusiasm over the social brain, social hormones, and social cognition must be tempered with evidence that being social is far from easy, automatic, or infinite. This is because our (social) brains, (social) hormones, and (social) cognition on which social processes rely must first be triggered before they do anything for us.
Humans Are By Nature Social Animals
One of the most compelling pieces of evidence for humans' ostensibly automatic social nature comes from Fritz Heider and Mary Simmel's famous 1944 animation of two triangles and a circle orbiting a rectangle. The animation depicts merely shapes, yet people find it nearly impossible not to construe these objects as human actors, and to construct a social drama around their movements. A closer look at the video, and a closer reading of Heider and Simmel's article describing the phenomenon suggests that the perception of these shapes in social terms is not automatic, but must be evoked by features of the stimuli and situation. These shapes were designed to move in trajectories that specifically mimic social behavior—if the shapes' motion is altered or reversed, they fail to elicit the same degree of social responses. Furthermore, participants in the original studies of this animation were prompted to describe the shapes in social terms based on the language and instructions the experimenters used. Humans may be ready and willing to view the world through a social lens, but they do not do so automatically.
Despite possessing capacities far beyond other animals to consider others' minds, to empathize with others' needs, and to transform empathy into care and generosity, we fail to employ these abilities readily, easily, or equally. We engage in acts of loyalty, moral concern, and cooperation primarily toward our inner circles, but do so at the expense of people outside of those circles. Our altruism is not unbounded; it is parochial. In support of this phenomenon, the hormone oxytocin, long considered to play a key role in forming social bonds, has been shown to facilitate affiliation toward one's ingroup, but can increase defensive aggression toward one's outgroup. Other research suggests that this self-sacrificial intragroup love co-evolved with intergroup war, and that societies who most value loyalty to each other tend to be those most likely to endorse violence toward outgroups.
Even arguably our most important social capacity, theory of mind—the ability to adopt the perspectives of others—can increase competition as much as it increases cooperation, highlighting the emotions and desires of those we like, but also highlighting the selfish and unethical motives of people we dislike. Furthermore, for us to consider the minds of others in the first place requires that we are motivated and possess the necessary cognitive resources. Because motivation and cognition are finite, so too is our capacity to be social. Thus, any intervention that intends to increase consideration of others in terms of empathy, benevolence, and compassion is limited in its ability to do so. At some point, the well of working memory on which our most valuable social abilities rely will run dry.
Because our social capacities are largely non-automatic, ingroup-focused, and finite, we can retire the strong version of Aristotle's statement. At the same time, the concept of humans as "social by nature" has lent credibility to numerous significant ideas: that humans need other humans to survive, that humans tend to be perpetually ready for social interaction, and that studying specifically the social features of human functioning is profoundly important.