Wednesday, April 2, 2008

The Liar Paradox in the Flesh


In Philosophical Psychopathology the psychiatrist and philosopher Bill Fulford describes a patient who was the living embodiment of the logical paradox "this statement is false" during a discussion on the difficulties in assuming delusions are false beliefs, as described in the standard definition.

"There is an even more fundamental sense in which delusions may not be false beliefs, namely that for some patients this would present us with a paradox.

I have reported one such case that occurred in Oxford... The patient, a 43-year-old man, was brought into the Accident and Emergency Department following an overdose. He had tried to kill himself because he was afraid he was going to be "locked up". However, this fear was secondary to a paranoid system at the heart of which was the hypochondriacal delusion that he was "mentally ill".

He was seen by the duty psychiatrist and by the consultant psychiatrist on call, neither of whom were in any doubt that he was deluded. Indeed, both were ready on the strength of their diagnosis to admit him as an involuntary patient.

Yet had their diagnosis depended on the falsity of the patient's belief, as in the standard definition, they would have been presented with a paradox: if the patient's belief that he was mentally ill was false, then (by the standard definition) he could have been deluded, but this would have made his belief true after all.

Equally, if his belief was true, then he was not deluded (by the standard definition), but this would have made his belief false after all. By the standard definition of delusion, then, his belief, if false, was true and, if true, was false." (p.211)

4 comments:

Hanno said...

This is not so easy to follow. Let me see if i get it.

P believes that he is crazy. Dr.X thinks P is crazy because P believes he is crazy, but he is not. That does appear paradoxical.

If P is crazy, then he is not crazy, or so goes one half of the dilemma, because his believe that he is crazy is true, and hence not delusional.

But this is not a true case of the liars paradox. Both arguments rest on an equivocation of crazy. P believes he is psychotic/schizophrenic. Dr. X believes P is a hypochondriac. Put those in for 'crazy' and you get a perfectly consistent picture.

P believes P is psychotic/schizophrenic. Dr. X thinks P a hypochondriac because P believe P is psychotic/schizophrenic, and P is not.

And so it in no way follows that if P is a hypochondriac, then he is not a hypochondriac. It does follow that if P is a hypochondriac, then he is not psychotic/schizophrenic. No problem.

MSU said...

Yeah, I think you are correct. Bill Fulford has led me astray with his obtuse language and strong conclusions!

__________________________________

Delusion = false belief

If a patient has a mental illness delusion they have a false belief about being mentally ill

If the patient is diagnosed with mental illness, then they are mentally ill.

However, if a patient is mentally ill, then they were not delusional. Hence, they did not have a false belief. They held a true belief.

Therefore, the person was not delusional.

Conversely,

If a patient has a mental illness delusion they have a false belief about being mentally ill.

If the patient is not diagnosed with mental illness, then they are not mentally ill.

However, if a patient is not mentally ill, then they were delusional. Hence, they held a false belief.

Therefore, the logic professor from McNeese is correct.

Rob said...

I'm not sure that I follow either of you, but now I have the urge to read Catch 22 again...

jfinnell said...

I believe the delusional patient's name was Yossarian