An abiding theoretical problem for psychiatry and philosophy is that, on most accounts of rationality, a severely deluded patient may qualify as quite rational. For instance, a paranoid psychotic patient may seem very plausible to a person not versed in psychiatry and even where he does not seem rational, his mistakes are often so minor that they fail to account for the evident thought disorder. Consider Mrs. A, who was examined by a forensic psychiatrist after she had killed her infant. She justified this action in the following way.