Or the right computer software. Humans are pretty basic machines. Feed the right texts to any intelligent agent, he will be able to predict human behavior pretty well. They are even more basic than normal people. Their reactions are rigid, boringly predictable.
Normal people are much more varied, unpredictable and interesting.
Same way as a blind man can discuss color, I guess. We can judge only derivative behaviors, not underlying emotions. We cannot communicate our inner world. We can discuss, analyze and dissect only the language that we use to discuss our inner world. I can decide to behave morally for the rest of my life - and not have an ounce of conscience.