The flies in logical positivism’s ointment

LOGICAL POSITIVISM IN THE 1950s and its influence on The Philosophy of EBM

The corporate medical establishment loves ‘Evidence’ and claims this is only contaminated by talk of ideology: Thus in an editorial in 2005:

Each side of the NHS debate accuses the other of being driven by ideology, without seeing that ideology is equally evident on both sides. Ideology makes things simple when in reality they are irretrievably complex. The private finance initiative (PFI) may have seemed ideologically sound but its lack of flexibility has stymied it in practice (p 792)—an expensive mistake. Meanwhile the new pressure group “Keep our NHS public” tends to ignore the inconvenient fact that the NHS has always worked with private practitioners.BMJ 2005;331:0-h

This misunderstands ideology which is most easily captured by the phrase ‘normative preference. The basis of Evidence Based Medicine is an empiricist logical positivism, so this article is a look at logical positivism’s logic through an article by Rudolf carnap in 1950.  It shows that the theory is great but in practice the names given to things or to abstract concepts are accepted and used on the basis of their context and their intent. Language is a social and economic tool that disperses power and subordination.

Rudolf Carnap, of the Vienna Circle, was responding to neo-Kantian controversies, Kant had distinguished between the sense-perceived and human constructs such as space and time and had postulated an intermediate epistemic mechanism that enables us to make ‘knowledge’ out of these two things, this intermediate mechanism was disputed by philosophers after Kant in a neo-kantian debate. Carnap I think denied any need for any intermediate epistemic mechanism but thought knowledge should only be based on an ‘accepted’ use of language, and was quite happy for empiricist nominalists to use abstractions as long as they didn’t believe these represented anything in the thing world.

The fly in his ointment is the idea that knowledge should be ‘based on language’ which presupposes that language itself can provide or determine all knowledge that can be known, i.e. language as having determinate meaning.   This is a decision that has profound ideological consequences, and emphasises just how important ideology is to the practice of medicine and how it determines was evidence is both generated and ‘accepted’.

Carnap  disagreed with Wittgenstein about the nature of logical syntax, for W this was only ever a display of what there is out there, for C this is ALL there is, any other questions are meaningless, C did away with metaphysics, his essay  is an important foundation for logical positivism and therefore important for EBM philosophy, EBM seems to have adopted Carnap. Bachelard et al, suggested that as the forms change historically so does knowledge.

“Empiricism, Semantics, Ontology”, Revue Internationale de Philosophie 4: 20–40. Carnap, R (1950)
But logical positivism leads to Zeno’s paradoxes, the asymptotic impossibilities, and I wonder if predictive diachronic diagnostic processes based on logical positivism also leads to a Zeno’s paradox, the impossibility of biological normality. Why put the logic of syntax on such a high plane so as to discount anything outside language like an unconscious, and psychic drives of alienated mortal traumas, of the symbolic castration – precisely the metaphysical I think.

So, for the practice of medicine,  an issue becomes whether a diagnosis named, the abstract term is of a real object or an abstract entity, does it represent a reality ‘out there’ or is it a human abstract form of thought. Is this a big question? Why would Carnap dismiss this, if he would? For nominalism, the abstract term exists, such as tree, but the abstract universal tree, the abstract object does not exist, this would be the metaphysical. The abstract. A borderline cancer is an abstract term, it exist but the universal abstract ‘borderline cancer’ does not exist, its an abstraction, it has no physical referent. Is this a problem for logical positivism? To repeat: better; nominalists do not believe that there is any physical referent for a universal abstract term, like a tree, or the colour green; whereas a realist might believe there is something physical that is common to all the universals, even if it is at the level of some kind of fundamental particle. OK – thought, to reject the metaphysical is to reject ideology, and Foucault’s sense of subjective transformations in history through a changing balance between egoist and collective interest in interests, or governmentalities. Ian Hacking says the positivists and the ‘social constructionists’ shout past each other.

The BMJ says “Evidence not Ideology”. Wrong, my challenge. “Evidence is ideology writ large” Naming Difference is an act with an egoist economic motive, and motivated by a more or less liberal political economy, to produce a product for a more or less free market economy, an act of more or less self-investment.

Carnap says empiricists more in sympathy with nominalists, ….. suspicious of abstract entities, like properties and class relations, experience perceived and felt, “My Body, this paper, this fire” is the thing. And yet, the EBM empiricists deal in abstract terms and objects all the time, so are they realists, or nominalist and does it matter? A pure empiricist should not deal in abstractions then? I think Carnap argues against this.

‘Accordingly, the mathematician is said to speak not about numbers, functions and infinite classes but merely about meaningless symbols and formulas manipulated according to given formal rules. In physics it is more difficult to shun the suspected entities because the language of physics serves for the communication of reports and predictions and hence cannot be taken as a mere calculus. A physicist who is suspicious of abstract entities may perhaps try to declare a certain part of the language of physics as uninterpreted and uninterpretable, that part which refers to real numbers as space-time coordinates or as values of physical magnitudes, to functions, limits, etc. More probably he will just speak about all these things like anybody else but with an uneasy conscience, like a man who in his everyday life does with qualms many things which are not in accord with the high moral principles he professes on Sundays.’ (p20, my bold)

Could we substitute ‘medicine’ for ‘physics’ in the above, and are the limits of physical magnitudes uninterpretable for the empiricist, such as the degree of abnormality of a tissue appearance, as an abstraction communicated in a pathology report. It sounds as though Canap is going to contradict this, so an important paper. It may be that normality is an abstract term, and does not exist in fact, therefore an empiricist evaluative investigation to detect spatio-temporal facts or events that rely upon an opposition to the non-existent normal must be flawed. The impossible question for medicine is not; “Is that tissue inflamed?” but “Is that tissue normal?”

Carnap’s empiricism seems to ignore the way language functions to disperse power through the construction of the objects of which it speaks (after Foucault), it also seems to ignore the contradictions and paradoxes that occur within the thing language, whereby e.g. several different names are given to (and function in respect of) a particular borderline ‘cancerous’ (to use a name, or metaplastic , or etc etc … if you prefer) tissue appearance. Similarly a physical quantity could be given different names in physics – a proportion such as 30% more blacks than whites or 70% less whites than blacks, can have very different social meanings, terms and their bias. You don’t have to believe in the thing world to feel differentially subordinated by the differentiating powers of different terms and contexts. This reminds me of Frege’s error, could go back to Pecheux to review this? Also re check difference between Bachelard and Kuhn in Le Court’s book.

‘An alleged statement of the reality of the system of entities is a pseudo-statement without cognitive content. To be sure, we have to face at this point an important question; but it is a practical, not a theoretical question; it is the question of whether or not to accept the new linguistic forms.[1] The acceptance cannot be judged as being either true or false because it is not an assertion. It can only be judged as being more or less expedient, fruitful, conducive to the aim for which the language is intended. Judgments of this kind supply the motivation for the decision of accepting or rejecting the kind of entities.’ (Carnap)

Here, we have language used with intention, motivation, which begs the question, not of the belief in the eternal thing world, realism, but a tacit acceptance that decisions about whether to accept the naming of things may depend upon egoist interests in (economic perhaps) interest and therefore be political, a tool of a particular governmentality and market. The speaker uses the new entities, the pure empiricist may take a higher ground and argue this in no way implies belief in the reality of the new entity, but the market will sell the new entity as if it is real, and consumers will demand it with their own mentalities shaped by the market’s use of language. This is where Evidence IS ideology. To deconstruct the power effects of the language of EBM is not necessarily to hold a belief in the thing world, but is based upon acceptance of language effects of power-resistance and motivation, egoist and collective interests, agendas and non-agendas, and therefore subordination and possible exploitation of the weak. The acceptance of the abstract entity ‘borderline pathology’ implies acceptance for the abstract entity ‘normality’ may not imply a belief in it, but a decision as to its (motivated) utility for the speaker. The acceptance opens the door to infinite overdiagnosis and hinders restraint of overdiagnosis. This isn’t to say that logical positivism and empiricism as applied to medicine doesn’t have a use where current illness or current undetected actual clear illness is concerned, but in the latter case there us always a problematic border the description of which is an ideological event.

[1] my italics, this might be a new diagnostic test result, a level of combinations of SNPs, a genetic fingerprint test, for example


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