Robert D. Hare, in his research on psychopaths:
"...a frightful and perplexing theme that runs through the case histories of all psychopaths: a deeply disturbing inability to care about the pain and suffering experienced by others – in short, a complete lack of empathy, the prerequisite for love."
James Gilligan, in his research on prison violence:
"So the person who cannot love cannot have any feelings – pain or joy. * * * But how can one know that others have feelings, or be moved by the feelings of others, if one does not experience any feelings oneself?"
Martha Stout, in her research on psychopaths:
"We have already seen that when someone's mind is not equipped to love, he can have no genuine conscience either, since conscience is an intervening sense of responsibility based in our emotional attachments to others. Now we turn this psychological equation around. The other truth is that should a person have no conscience, he could never truly love. When an imperative sense of responsibility is subtracted from love, all that is left is a thin, tertiary thing – a will to possess, which is not love at all."
Robert D. Hare. Without Conscience: The Disturbing World of the Psychopaths Among Us. Atria, 1993. (Released by Guilford Press for Kindle, 2011.)
James Gilligan. Violence: Reflections on a National Epidemic. (1996) New York: Vintage Books, 1997. p. 52.
Martha Stout. The Sociopath Next Door. Harmony, 2005. (Released by Random House Digital for Kindle.)