Dr.med. Othmar Mäser, Psychiater Psychotherapie

medical diagnosis – psychiatric diagnosis

The basic principles of medical knowledge and psychiatric knowledge are examined here through reference to Immanuel Kant`s treatise “Critique of Pure Reason“.

In particular, the difference between medical diagnoses and psychiatric diagnoses (diagnoses of mental disorders) is demonstrated referring to Immanuel Kant`s philosophy.

As we know special diagnostic problems exist in psychiatry and in certain parts of medicine. Referring to Immanuel Kant` s philosophy the cause of the diagnostic problems can be demonstrated and, furthermore the consequences resulting from this difference in the basis of the knowledge can be shown.

(The English edition of this page was started on 12th August 2009 and is still under development.)

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The German edition of this page, medizinische Diagnose – psychiatrische Diagnose and the articles on the blogs are at a more advanced stage of development.

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There are different levels of knowledge (-> Kant quotation 9) and in medicine this is no exception: some knowledge is with certainty objective and other knowledge is with certainty subjective; some knowledge is tangible while other knowledge is only vague and less tangible. In medicine, there is knowledge gained from evidence which is based on objective knowledge and there is knowledge gained from evidence which is based on subjective knowledge. In psychiatry, all knowledge is based on subjective knowledge.

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With reference to Immanuel Kant`s Critique of Pure Reason, it can be shown that symptoms and phenomena are ideal objects, which we conceive as terms in our mind.
In contrast, medical signs (physical signs) refer to real objects, to objects in an absolute sense. Therefore, many medical diagnoses can be determined objectively on a physical basis.
Ideal objects, such as psychopathological phenomena and symptoms, are
mental schemes (schemes of terms in the mind) which do not refer to real objects and, consequently, we cannot prove them on a physical basis, only carefully weigh them in our mind and ponder the presence of a phenomenon (symptom).
This is the major difference between objective medical diagnoses, on the one hand, and psychiatric diagnoses and medical diagnoses that cannot be proven on a physical basis, on the other.

An “ideal object” - which Immanuel Kant termed “Gegenstand in der Idee” in German - is not an object in the strict sense but is a “mere idea”, a schema, which does not relate directly to an object, not even in a hypothetical sense…”  (see Kant quotation 7).

These differing objects mirror the differences in signs and symptoms (phenomena) and, consequently, the difference between medical diagnoses and psychiatric diagnoses (diagnoses of mental disorders).

It is through the basic differences in medical knowledge that some diagnoses can be proven by various diagnostic criteria, on a “physical” basis, whereas other diagnoses such as tension headache, migraine, somatoform pain disorder and fatigue syndrome, and also mental disorders (psychiatric diagnoses) cannot be proven on a “physical” basis; such diagnoses can be evaluated just by “pondering” in mind on the level of ideas if a diagnosis applies or not.

Thus, some diagnoses, namely, the ones which can be tested on  a “physical” level, can be reached objectively (-> compare To Kant quotation 9), which means every expert comes to the same diagnosis. Such objectivity is impossible in diagnoses based on symptoms alone, such as tension headache, migraine, somatoform pain disorder, and fatigue syndrome, for example, and all mental disorders; it often happens that experts reach different diagnostic results. This is particularly the case in psychiatry if the “clinical picture”, the complex of symptoms, is not very typical.

Psychiatric diagnoses and medical diagnoses which are reached on the basis of symptoms (phenomena) are not objective knowledge but only subjective knowledge. The degree of knowledge may be conviction (subjective sufficiency) or opinion (consciously insufficient). In medical knowledge the degree of knowledge may be certainty (necessarily valid for everyone) for objective medical diagnoses and, conviction (subjective sufficiency) or opinion (consciously insufficient) for symptom based medical diagnoses. (-> compare To Kant quotation 9).

Prognostic statements in medicine are always the result of “speculative reasoning”, therefore such knowledge is always only hypothetical and, consequently, the “Critique of Pure Reason” applies also in this case. This shall be shown in the articles, with examples.

Finally, the consequences resulting from the different basis of the knowledge are shown and, in the articles, reference is made to considerations necessary in practice, education and research, in medicine as well as in psychiatry (psychology and psychotherapy).

An introduction to the subject is on this page.

Further details are contained in separate articles.

Link to published posters and articles.

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A note for readers:  There are repetitions of the content on this page and in the articles. This has resulted because, on the one hand, it can’t be avoided and, on the other hand, it seems to be useful since the references to Kant’s knowledge are repeated in slightly different ways in different parts of the text, making the core of Kant’s ideas easier to understand. Since this page is under development, please accept my apologies for any mistakes you may find.

At the very end of this page is a listing of selected Kant quotations.

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Immanuel Kant wrote:

“Thus all human cognition begins with perceptions, proceeds from thence to conceptions, and ends with ideas.” ( Kant quotation 1)

( modified version of J. M. D. Meiklejohn’s translation)

It will be shown how knowledge in medicine and psychiatry (psychology and psychotherapy) starts with sensory perceptions, arrives firstly at conceptions, the terms for symptoms and signs and for the phenomena revealed in the mental status examination and, from there, progresses to a diagnosis an idea (as an illustration see this pdf-power-point presentation).

At this point, it may be mentioned that in this diagnostic process, the lowest level of investigation, namely the level leading from “sensory perceptions” to terms for symptoms and signs (phenomena), has not yet been regarded as being of importance since philosophical discussion dealing with this level of knowledge has faltered at the lack of a philosophy which points it out.  The Critique of Pure Reason delivers this philosophy and makes it possible to discern what should be taken into consideration in order to reach the best possible results in knowledge. In the Critique of Pure Reason, Immanuel Kant demonstrates what are the borders of knowledge in the sphere above “physically” provable knowledge, the knowledge that is transcending the limits of experience. (-> Kant quotation 10)

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A medical diagnosis is a systematic unit which conceives a medical condition or disease as within this systematic unit, through  its signs and symptoms.

The diagnosis of a mental disorder is also a systematic unit which conceives  psychological and behavioural signs and symptoms, within this systematic unit. However, in this case the unit is a mere idea, according to Kant, an idea that cannot be proven from experience. (compare To Kant quot. 10)

When medical diagnoses are compared, one finds that some of them can be proven through various diagnostic procedures, on a “physical” basis, directly or indirectly, to make sure an assumed diagnosis is true. In other cases, such a procedure of assurance for medical diagnoses is impossible – Immanuel Kant calls these ideas, “mere ideas”.

With this in mind, one finds that no assumed mental disorder can be proven by a diagnostic procedure on a “physical” basis. In the case of mental disorders and symptom based medical diagnoses, one can only ponder in mind on whether an idea corresponds or not, to what extent it does so, and to what extent one of the ideas is of relevance. Thus, in this field, knowledge cannot be “proven” on “physical” level – on a mental level one can only “ponder” on it, which means one can “ponder” the ideas against each other. This is the great difference between objective medical diagnoses and mental disorders; between somatic medical knowledge, which can be reached objectively and psychiatric knowledge which is subjective and not objective.

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When taking a look at the deepest roots of medical knowledge, one finds it is concerned with sensory perception / sensory information and the processing of this information. So, in the beginning, we have a sensory input and the processing of this information. Through the processing of this information we arrive at the symptoms and signs which are represented by terms. So one soon finds that the further processing of the information is dependent upon terms, about which we can think further.

In the first step we conceptualise the sensory information under terms, this being the function of understanding, then, we reason about these terms and think, for example, under which category (diagnosis) the terms might be subsumed.  (see Kant quotation 1)

The terms, therefore, are crucial and determine which diagnosis is reached, and whether the diagnosis can be determined in such a way that all professionals arrive at the same diagnosis.

Immanuel Kant shows  “that agreement of judgements with each other, in spite of the different characters of individuals, rests upon the common ground of the agreement of each with the object“. (see Kant quotation 9)

This is the reason why professionals agree in the judgement about “objects in an absolute sense“.

If, on the other hand, the knowledge rests on perceptions which lead to certain terms that represent ”ideal objects” there is no such a common ground of the agreement. In this case there is only subjective knowledge. (see Kant quotation 9).

The more the impressions resulting from perceptions are typical the more often it happens that professionals agree in a judgement about ideal objects while on the other hand if the impressions are not very typical often it happens that professionals arrive at different judgements, which means they arrive at different terms and furtheron at different diagnoses.

This happens in medicin where the diagnosis cannot be proven on a physical basis (tension headache, fibromyalgia e.g.) or in psychiatry if the clinical picture (the complex of symptoms) is not typical.

So one can say if the terms of the characteristic signs represent real objects an objective diagnosis can be reached. If a diagnosis is based on symptoms and phenomena which are ideal objects no objective diagnosis can be reached.

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In the diagnostic process there is, on one hand, information delivered by the patient and, on the other hand, information identified by the person who does the investigation and examination.

When medical diagnoses can be reached objectively, we find that crucial information is of a “physical” nature.

However, with medical diagnoses which cannot be determined objectively, we find that crucial information depends upon the symptoms described by the patient and by the person who does the examination and investigation.

In psychiatry, the crucial information the diagnosis is determined by the psychological and psychopathological phenomena which are of the same nature as the symptoms in medical diagnoses.

Kant postulated that all these ideas are “objects in idea form” or “ideal objects” (objects in a person` s mind).

On the other hand, “physical” signs and the results of various diagnostic procedures which determine a medical diagnosis objectively, for example, ECG findings and laboratory findings in myocardial infarction, are all of a “physical” nature.

Immanuel Kant called a object in an absolute sense in German a “Gegenstand schlechthin”.  In Kant quotation 9, he explains why only knowledge about such real objects leads to the same understanding for them, which means that such knowledge is objective, because agreeing about an object with each other results from the fact that everyone has accepted the same term which is applied to this object.

(This is the reason why for example research to determine objective criteria for schizophrenia continues.)

If considering something to be a particular thing is an object in mind (“object in idea form”) , for example, a symptom or psychopathological phenomena, there is no reason why different persons should arrive at the same term – especially if the thing being determined, e.g. the symptom or the psychopathological phenomenon, is not typical. Only if the thing is typical, almost every professional will arrive at the same result. Since symptoms and psychological and psychopathological phenomena are “objects in mind” (objects in a person`s mind) they are the result of perceptions and judgements of the person who is conceiving the perceptions and is thinking about them and , therefore, it is not to be expected that everybody will arrive at the same result.  So there is a great difference between real objects and objects that are just presented to us as an ideal object (object in idea form) (compare Kant quotation 7).

Objects that are ideal objects (objects in idea form) are schemes to consider other objects within this schema. Because these objects are not real objects but are only objects in mind, or putting it another way, these objects exist just as an object of the person’s imagination . Immanuel Kant calls such ideas mere ideas. Psychological ideas as well as psychopathological ideas are mere ideas. (compare Kant quot. 4 and Kant quot. 8)

It should be noted however that on Wikipedia page Medical diagnosis it is mentioned and discussed that medical diagnosis in psychology or psychiatry is problematic (see Wikipedia page Medical diagnosis : Chapter Diagnosis in medical practice).

These diagnostic problems in psychiatry (psychology and psychotherapy) result as a consequence of the basis of the knowledge of the former mentioned disciplines. To say it in other words the difference in the basis of the psychiatric (psychological, psychotherapeutical) knowledge compared to the basis of the knowledge in objective Medicine is the reason why diagnostic problems result which are not known in objective Medicine (but happen in the part of Medicine which is only symptome based).

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Links to articles of the blog medical diagnostics:

medical diagnosis

psychiatric diagnosis

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object in an absolute sense

ideal object (object in mind)

regulative concept

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psychological idea

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Griesinger quotation

Bleuler quotation

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Links to

Questions and Answers

Links to Kant quotations:

Kant qutotation 1 – human cognition

Kant quotation 2 – highest faculty of cognition

Kant quotation 3 – boundaries  of knowledge

Kant quotation 3a – right and wrong use of an idea

Kant quotaton 4 – psychological idea

Kant quotation 5 – hypothetical exercise of reason

Kant quotation 7 – real object - versus - ideal object (object in mind)

Kant quotation 8 – mere idea – a systematic unity

Kant quotation 9 – opinion, knowledge, belief

Kant quotation 9b – probability – versus – appearance

Kant qutotation 10 – Preface to the Critique of Pure Reason

Kant quotation 13 -Schema

Kant quotation 14 - Concept

Kant quotation 25 - Principles

Kant quotation 26 - regulative principle

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Link to published posters and articles

Posters published in the series - Psychiatry and medicine in the light of Immanuel Kant`s philosophy

(This page is under development the last update was done on 25.8.2010)

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Link to Publications / Presentations

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Link to return to the top of the page

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