Thinking comes in many forms, from solving optimization problems and playing chess, to having a smart conversation or composing what experts would consider a fine piece of original music. But when I think about machines that purportedly think, I mostly wonder about what they might be thinking when the topics are inherently human, as so many topics inherently are.
Consider Bertrand Russell's touching description in "What I Have lived For": Three passions, simple but overwhelmingly strong, have governed my life: the longing for love, the search for knowledge, and unbearable pity for the suffering of mankind. These passions, like great winds, have blown me hither and thither, in a wayward course, over a deep ocean of anguish, reaching to the very verge of despair." Although Russell was a celebrated thinker, what he describes, in one form or another, is familiar to us all. But what would a machine do with all this? Could it really feel a longing for love? An unbearable suffering for mankind? Could it be blown hither and thither over an ocean of anguish, reaching the verge of despair?
Of course, if we accept some version of the computer metaphor of the mind (and I do), then all these sentiments, at the end of the day, must be the products of physical processes, which, in theory, can be instantiated by a machine. But the topics themselves so often are so human. If we agree that it is hard for men to fully understand maternal love; that the satiated may not be able to grasp what it feels like to endure starvation; that the free may not fully comprehend what it's like to be imprisoned, well, then, machines, no matter how well they "think," may not be able to think of so many things.
And those things are at the core of human experience. At the opera, we feel for Aida, who is horrified to hear herself call out "Ritorna Vincitor," finding herself torn between her love for Radames, and her devotion to her father and her people. Could a machine feel torn like Aida, or even moved like the rest of us when we see her beg the gods to pity her suffering? Can a machine experience fear of death without living? Lust without having sexual organs? Or the thoughts that come with headaches, wrinkles, or the common cold? It's easy to imagine a machine dressed in a Nazi uniform and another machine we can call Sophie. But when the former forces the latter to make a perfectly horrific choice, can the first experience the sadism and the second an irreparable desperation of the kind that was rendered so palpable in Styron's story?
If machines cannot truly experience the sort of thinking that incorporates the passions and the sorrows of the likes of Russell, or Aida, or Sophie; if they cannot experience the yearnings, desires, determination, and disgrace underlying the thinking of Lolita's Humbert, Conrad's Kurtz, Melville's Ahab, or of Anna Karenina, if they cannot do any of that, then perhaps they cannot really fully think.