The "psychogenic inference" is the inference that "if the physical cause of a condition can not be found, the cause must be psychological". Though this "siren" inference has been much criticised, it is still pervasive in medical and psychiatric thinking.

The presentation will examine this inference.

The method is that of careful logical analysis. The presentation will set out the seductive charms of the psychogenic inference, which include a surface plausibility and an apparent usefulness in practice. It will illustrate some of the hidden perils by reference to the characterization of Somatoform Disorders in DSM-IV and to debates about Chronic Fatigue Syndrome. It will then set out a set of alternative inferences which provide a safe escape route from the difficulties.

The "siren" psychogenic inference is deeply flawed and is the source of some current major difficulties. Alternative inferences are preferable.

1. 1. The psychogenic inference has done much harm and should now be firmly and finally eliminated.

2. 2. Alternative inferences should be made when the physical cause of a condition can not be found.

3. 3. The characterization of Somatoform Disorders in DSM-IV needs revision.