It’s hard to imagine a more fundamental question for psychology than what it is that makes us human. It’s harder still to come up with an acceptable answer. Great thinkers through the ages have puzzled over the nature of human nature, and so have contemporary psychological theorists. Are we rational animals, intuitive scientists, naked apes, information-processing machines, or battlefields of intrapsychic conflict? Many writers have made suggestions about what makes us human or wthat defines our humanity, some less serious than others (Mark Twain: "Man is the only animal that blushes. Or needs to"). Or is there perhaps no human nature at all, as the existentialists thought, no definition of humanness that works? Plato suggested "featherless biped", only to be refuted when Diogenes produced a plucked chicken.
