Definitions

…Freud claimed his theories to be scientific ones… But for some of the central propositions of Freudian theory it is not clear whether they are falsifiable at all. …The postulate of psychic determinism leads to specific propositions such as that all dreams are disguised wish-fulfilments. Can this be tested? Where an interpretation in terms of an independently established wish of the dreamer is proposed and accepted, well and good. But what if no such interpretation is found? A convinced Freudian can still maintain that there is a wish whose disguise has not been seen through. But this would make it impossible to show that a dream is not the disguised fulfilment of a wish, and would therefore evacuate the proposition of any genuine empirical content, leaving only the prescription that we should look for a wish fulfilled by the dream. The proposition can be empirical only if we can have independent evidence for (a) the existence of the wish and (b) the correct interpretation of its disguise.

Consider next the postulation of unconscious mental states and in particular the tripartite structure of id, ego, and superego. Freud did not of course expect these entities to be visible or tangible…. But that was because he had…abandoned any hope of discovering a physiological basis in the brain for such mental factors. …we must ask ourselves whether the postulation of unconscious mental states offers any genuine explanation of human behaviour. It would be too quick a move to dismiss them just because they are unobservable, for scientific theory often postulates entities which are not directly evident to any of the human senses - e.g. atoms, electrons, magnetic fields, and radio waves. But in these cases there are clear 'correspondence rules' connecting the unobservable entities with observable phenomena, so that, for instance, we can infer the presence or absence of a magnetic field from the visible behaviour of a compass needle. The trouble with many of the Freudian entities is that there are no such unambiguous rules for them. Stamp collecting may be asserted to be a sign of unconscious 'anal retentiveness', but could one show that such an unconscious trait is not there in someone?

Seven Theories of Human Nature. Leslie Stevenson. (Oxford University Press, 1974). Pages 73-74.