Group thinking is the notion that natural selection favors what is good for the group or the species, not for the individual. Most mainstream evolutionary biology rejects this idea and natural selection is viewed as working on the individual’s genes to promote their own survival and reproduction. Here I show through a couple of examples how group thinking also pervades economics. I argue that the reason for the mistake relies on the fact that economics fails to ground itself in the underlying knowledge provided by biology. Then I suggest how economics can aspire more than being applied logic and turn into a scientific discipline by placing biology on its basis. Finally, I outline how economics should treat group behavior properly.