Epistemology of Madness

1.0 Epistemology and Madness in Context
1.1 Epistemology, the study of the knowledge and scope of knowledge (intellectual and experiential), and the groundings and justifications of claims. It is differentiated from ontology (being, becoming, existence).
1.2 As an epistemological review it is not the reality of madness that is reviewed here (e.g., a review of causes); but rather how does one know whether a behaviour or person suffers from madness.
1.3 'Madness' has a number of definition; it can refer to insanity, folly, rage, or intense enthusiasm (as a proper noun, it can also refer to a 1970s/1980s popular ska band). It is mainly the former sense that is discussed in this presentation, although one could suggest that the definitions can be associated with the primary definition.
1.4 Note that 'insanity' derives from the Latin for 'not healthy' (sanus), a "sickness of the mind". Thus insanity can be considered a defective mental process.

2.0 Premodern and Non-Philosophical Criteria
2.1 Early analogous associations with mental health and physical health are well-known as were treatments (c.f., Torrey). Early civilisation would apply magic spells and potions (Egyptian, Babylonian), Indian, Greek, and Chinese medicine would argue that mental illness was the result of fluid imbalances or elemental movements (dosha, humours, Wu Xing) respectively) which would be reflected in behaviour. In comparison Christian Europe was very inconsistent, assigning causality to both humours and matters of faith; but again primarily to behaviour.
2.2 In the Islamic world mental disorders represented possession by a spirit and an individual with such a condition (majnoon) and could be determined by a loss of reason. Islam also applies a legal standing for such people, required care, and also provided the earliest mental health institutions (Baghdad, 705CE).
2.3 Mental health laws came into existence in the mid-19th century with the British Lunacy Act 1845 of importance. It defined mentally ill people as patients, and therefore under medical care. Whilst the primary focus was to ensure the proper treatment of the mentally ill in asylums, it also ensured the presence of medical professionals, who will take the evaluative and determining role from the basis of clinical symptoms, as well as having legal authorisation of determination (diagnostic congruence varies greatly; e.g., major depressive disorder, a common mental illness has a kappa statistic of 0.28 whereas major neurocognitive disorder has 0.78).

"As the dominant social ethic changed from a religious to a secular one, the problem of heresy disappeared, and the problem of madness arose and became of great social significance.... the creation of social deviants, and shall show that as formerly priests had manufactured heretics, so physicians, as the new guardians of social conduct and morality, began to manufacture madmen."
- Thomas Szasz, The Manufacture of Madness: A Comparative Study of the Inquisition and the Mental Health Movement

3.0 Madness as abnormality
3.1 It is common for insanity to be described as significant deviance in thought or behaviour from social averages or normative positions (e.g., Szasz, Foucault) which generates extreme discomfort in others (even outrage - ironically, a type of madness), the strongest reactions typically being on matters of sexuality and gender in contemporary society.
3.2 In psychological assessments, deviant thought processes may be defined as an insanity, although deviant behaviour is more likely result in incarceration. Of particular interest to epistemology, the combination of deviant thought and behaviour results in a different form of institutional incarceration compared to normal mental processes with deviant behaviour (insanity versus criminality), which often leads to feigned insanity (Mafia leader Vincent Gigante attempted to feign dementia in the late 1960s). The Rosenhan experiment (1973) illustrated a core problem with mental health diagnosis (pseudopatients feigned auditory hallucinations; non-existent impostors were evaluated as such).
3.3 Abnormality is inevitably contextual, a continuum and malleable, making an epistemology based on such criteria difficult, even if this is the most common manner of making diagnostic assessments of mental health. It does not necessarily imply that the thoughts or the behaviours are dangerous which makes assessment (and the subsequent loss of legal rights) extremely problematic.

4.0 Madness as delusion, hallucination etc.
4.1 Delusion are incorrigible beliefs held with certainty despite superior contrary evidence and can be distinguished from beliefs based on incomplete or otherwise distorted information (e.g., hallucinations). Bizarre delusions are those were are considered implausible (an example named by the DSM-5 is a belief that someone replaced all of one's internal organs with someone else without leaving a scar). With grandiose delusions an individual is convinced they have special powers, purpose, abilities etc. Powerful delusions (from an epistemological point of view) are those which are protected from external evaluation.
4.2 Hallucinations is a perception of an object or event in the absence of external stimulus that has qualities of real perception (a delusion may be a normal perception but is interpreted in a delusional manner). Diagnosis is invariably associated with discovering the cause in order for treatment; an approach that draws correlation between brain damage and mental damage (and in some epistemologies, a necessary association). Because perception is a subjective experienced of the objective world, diagnosis is limited to the degree of intersubjective agreement on whether a hallucination has occurred - a common problematic theme in literature (e.g., Phillip K. Dick novels, 'The Shadow' (1994 film) etc - for narrative reasons the subject is typically shown as the 'sane' person). Collective hallucinations, infectious behaviour.
4.3 Another variation is 'repressed memory syndrome' which was has some evidental support (individuals forgetting traumatic events) but was more subject to a moral panic in the 1980s and 1990s with false reporting often generated by controversial techniques e.g., 'guided therapy' with hypnosis, creating iatrogenic results - also common in multiple personality disorder evaluations.

5.0 Madness as incoherence
5.1 In epistemology, coherence is a theory of truth argues for theoretical holism for sufficient proof, where an entire system of propositions has a consistent internal structure; systematic coherence requires more than logical consistency. In linguistics coherence refers to how a text becomes semantically meaningful, sometimes described as a "continuity of senses". It is argued that linguistic coherence also builds mental frameworks for the organisation of information about the world.
5.2 If this framework is somehow incorrect, incomplete, or broken ("crazy" means "cracked" in Middle English), then it implies that the mental state of the individual will also suffer, and by extension, so may their behaviour. Cognitive dissonance, as the mental stress or discomfort experienced by an individual who holds two or more contradictory values at the same time, is an example of a type of incoherence.
5.3 As a interpretative model coherence therapy suggests that irrational thoughts and behaviours are expressions of existing constructions of the self and their relationship to the world, which can be reconstructed and guided to a more complete state - again assuming that a continuum is in place between perfect coherence and complete incoherence and that there is partiality in areas of mental topics. Resolving matters of incoherence has been shown to significantly contribute to mental health and rehabilitation.

6.0 Concluding remarks
6.1 Abnormal behaviours in themselves cannot be held to constitute madness from an epistemological perspective, although they may be symptomatic and of a medical issue if it they are harmful to the subject or others; expressions of delusions or hallucinations have stronger evaluative potential and may act as a strong predictor of irrational behaviour. Incoherence can elaborate from delusions etc, which illustrates a break in a chain of reasoning which in principle can be patched and provide a means of overcoming irrational behaviour.

Some References

American Psychology Association, Diagnostic and Statistical Manual of Mental Disorders (various editions)
Sidney Bloch, Bruce S. Singh, Understanding Troubled Minds
Michel Foucault, Madness and Civilization: A History of Insanity in the Age of Reason
Thomas Szasz, The Manufacture of Madness: A Comparative Study of the Inquisition and the Mental Health Movement
E. Fuller Torrey, The Mind Game: Witchdoctors and Psychiatrists