Meaning of Delusion

The delusions Opens in new window of the mad are not well received by the sane. At best, they have been treated as harmless and humorous, but often they have been regarded as deliberate attempts to deceive or as evidence of demonism.

The English word delude comes, of course, from Latin and implies playing or mocking, defrauding or cheating.

The German equivalent Wahn is a whim, false opinion or fancy, and makes no more comment than the English on the subjective experience.
The French equivalent, délire, is more empathic; it implies the ploughshare jumping out of the furrow (lira), perhaps a similar metaphor to the ironical ‘unhinged’.

Delusions and Insanity in Law

Delusion has been considered in law to be the fundamental feature of insanity.

“Delusions therefore, when there is no frenzy or raving madness, is the true character of insanity”, stated Lord Erskine defending Hadfield, who, when clearly mentally ill, fired at King George III in 1800 (West and Walk, 1977).

The special verdict of not guilty by reason of insanity can be brought in English law only when the degree of insanity satisfies the Rules Laid Down by Judges, generally called the McNaughton Rules Opens in new window.

These rules were drawn up in the mid-nineteenth century by judges in the House of Lords as definitive guidance following the attempted assassination of the Prime Minister by McNaughton.

They state, ‘To establish a defense on the ground of insanity it must be clearly proved that, at the time of committing the act, the party accused was laboring under such a defect of reason from disease of the mind, as not to know the nature and quality of the act he was doing was wrong’.

The rules would be fulfilled by a man who bisects his victim with a meat cleaver believing the latter to be a carcass of beef or by someone who shoots another person believing them to be an enemy assassin and himself to be the Queen’s personal bodyguard.

These McNaughton Rules are restrictive and exclude many defendants who are undoubtedly psychotic; more detailed consideration will be found in Wasik (1990).

They are now rarely employed, the plea of diminished responsibility Opens in new window being more frequently used in defence for homicide, but the McNaughton Rules remain the basis for the legal concept of insanity.

Definition of Delusion

There continues to be much debate and controversy about the definition of delusions. The standard approach is to follow Jaspers’ (1959) claim that delusions are manifest in judgments and arise in the process of thinking and judging.

For Jaspers, the characteristics of delusions are that:

they are false judgments,
they are held with extraordinary conviction and incomparable subjective certainty,
they are impervious to other experiences and to compelling counterargument and
their content is impossible.

Each of these criteria has been subjected to criticism. Delusions may not be false insofar as the content is concerned. This is best exemplified in delusional jealousy, whereby the belief may correspond to objective truth and is therefore not false.

Delusions may not be held with extraordinary conviction but, equally, normal beliefs may be held with extraordinary conviction.

Delusional beliefs may also be amenable to counterargument, although it is rare that this by itself will alter the belief. Finally, delusional content need not be impossible.

There is a growing body of opinion that delusions are not beliefs at all. Spitzer (1994), for example, argues this case. He makes the distinction between ‘to know that’ and ‘to believe that’.

In Spitzer’s view, delusions make knowledge claims rather than belief claims. In other words, patients are asserting that they ‘know such and such’ rather than they ‘believe such and such’, which is why delusional statements are expressed with conviction and certainty and not subject to discussion and inquiry.

Berrios (1996) comes to the same conclusions. He states that ‘delusions are empty speech acts which assert themselves as beliefs’. Furthermore, he makes the point that the content of delusions is incidental to the fact of the phenomenon being a delusion.

In Berrios’ view, the content of delusions is randomly chosen; the content merely reflects whatever is in the environment at the time the delusion is formed. The content is lacking in informational quality and is not ‘symbolic expression of anything’.

These critiques of the current definitions and understanding of delusions underline the complexity of the conceptual status of delusions and show that there is still fruitful theoretical work to be done in psychopathology. For the purpose of this literature, it is best to conceive of delusions as false beliefs.

The decision to call a belief or judgment delusional is not made by the person holding the belief but by an external observer.

There can be no phenomenological definition of delusion, because the patient is likely to hold this belief with the same conviction and intensity as he holds other non-delusional beliefs about himself, or as anyone else holds intensely personal non-delusional beliefs.

In this respect, delusions are to ideation what hallucinations Opens in new window are to perception. Subjectively, a delusion is a simply a belief, a notion or an idea.

Stoddart’s definition of a delusion (1908), ‘a judgement which cannot be accepted by people of the same class, education, race and period of life as the person who experiences it’, has some advantages.

However, it could include as delusional falling in love with a person others regard as unsuitable, having a minority religious belief or holding any unusual idea without acknowledging reasonable argument to the contrary.

Hamilton (1978) defined delusion as ‘A false unshakable belief which arises from internal morbid processes. It is easily recognizable when it is out of keeping with the person’s educational and cultural background’.

Rather than suggest a unitary definition for delusion, Kendler et al. (1983) have proposed several poorly correlated dimensions or vectors of delusional severity:

Conviction: the degree to which the patient is convinced of the reality of the delusional beliefs.
Extension: the degree to which the delusional belief involves areas of the patient’s life.

Bizarreness: the degree to which the delusional beliefs depart from culturally determined consensual reality.
Disorganization: the degree to which the delusional beliefs are internally consistent, logical and systematized.
Pressure: the degree to which the patient is preoccupied and concerned with the expressed delusional beliefs.

Two other dimensions that might also be considered are as follows:

Affective response: the degree to which the patient’s emotions are involved with such beliefs.
Deviant behavior resulting from delusions: patients sometimes, but not always, act on their delusions.

The term delusion is used frequently in ICD-10 but is not defined there. It is referred to in all the major categories of organic mental disorders, substance misuse, schizophrenia and affective disorders, and its presence excluded from the category of neurotic disorders.

Delusions are entirely different from thought disorder Opens in new window:

delusions are ideas that the patient believes to be true but an observer considers false;
formal thought disorder is the alteration from normal that the patient himself describes subjectively in his thinking processes.

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Meaning of Delusion