If people can be simulated, how do you know what's true? If your own mind were leading you astray, would you even notice?
Chloe is a beautiful humanoid companion. Deliberately implanted in the programming of her mind is a minor reasoning defect. Whereas an ordinary person could live with it, and perhaps not even be aware of it, Chloe cries and has fits whenever she becomes aware of the flaw in her chain of thought. A psychologist is brought in to figure things out.