Marginalism, reductionism, realism

There is a large literature documenting the socioeconomic gradient in health. Whether it be measured by education, income or some other metric, individuals of a lower socioeconomic status have worse health. Understanding and explaining this gradient is of great importance to improving public health; however, the way we approach investigation and application depends on our ontological and epistemological position which is often not addressed in practice but is implicit in any analysis we do.

Many have tried to explain socioeconomic gradients in health through either access to healthcare or genetics. But, gradients have widened over time within countries with little change to the genetic make-up of the population; and, there is often little difference in measured gradients between countries with universal healthcare funded through taxation (e.g. the UK) and insurance funded healthcare with known access issues (e.g. the US) (Dow and Rehkopf, 2010).

This then leads us to differences in risk factors for the main causes of death in Western nations. There does exist well documented gradients in obesity and smoking. But, gradients in exposure to risk factors often differ from gradients in mortality; for example, Southern European countries have a wider mortality gradient than Northern European countries but have a narrower obesity gradient (Mackenbach et al, 2008). Although, smoking may better explain this difference. To succinctly summarise this – it is a complex relationship.

Our aim as researchers is to obtain knowledge about this system to attempt to provide causal explanations of relationships between social and economic changes and biological outcomes. Clearly, we should have in mind that our explanations need to have a plausible biological aetiology. But, focussing here on solely the social and economic factors, we need to consider our ontological position.

The neoclassical approach posits individual, atomistic agents maximising utility by making rational choices about consumption and investment in health. This approach is exemplified by the Grossman (1972) model. Individuals ‘demand’ health on the basis of the cost of health capital and rate of depreciation. One immediate philosophical objection to this set up is the implicit dualism – the separation between the mind (the rational decision maker) and their body (their health). This dualism clearly makes little sense when mental health is considered. A more tangible objection arises since these models only consider agency and not structure. An implication of these models are that individuals’ choices about health related goods and behaviour are determined by their relative costs to the individual; there is little or no allowance for decisions to be affected by culture or society. It is ideologically individualistic.

Piero Sraffa, an influential Italian economist, developed a critique of the neoclassical approach (strictly speaking it was a ‘prelude to a critique’). One of his objections was with marginalism. He was writing about production in the economy and the problem of estimating the marginal product of a particular factor of production. He argued that the marginal product didn’t make sense since any change to the levels of any one of the factors of production would change the way it combines with any other factors of production, and the proportions they combine in. When we consider the aforementioned health ‘production functions’, we have the same issue. Merely altering income will not necessarily change health since the way in which income combines with, say, education or the local environment, will change. At the societal level, the way these interact are the result of institutions, ideology and culture.

Thus, when we estimate the effect of socioeconomic factors on health outcomes, we should, at a minimum, allow for differential effects by socioeconomic status. In interpretation and application, it may suggest that a policy of just redistributing income may not be enough – a better understanding of individual motives and heterogeneous culture is required to target policy. Many branches of economics that are considered heterodox, such as institutional economics, post-Keynesian economics and political economy analysis take account of social norms and economic institutions. But, the roles of sociology and psychology are also of great importance. This suggests the need for methodological pluralism, certainly when examining socioeconomic determinants of health, but also in general. It is perhaps best summarised by the following quote from Keynes:

The master-economist must possess a rare combination of gifts …. He must be mathematician, historian, statesman, philosopher — in some degree. He must understand symbols and speak in words. He must contemplate the particular, in terms of the general, and touch abstract and concrete in the same flight of thought. He must study the present in the light of the past for the purposes of the future. No part of man’s nature or his institutions must be entirely outside his regard. He must be purposeful and disinterested in a simultaneous mood, as aloof and incorruptible as an artist, yet sometimes as near to earth as a politician.


2 thoughts on “Marginalism, reductionism, realism

  1. The same could (and should) be said for physicians, as Virchow (amongst others) understood very well. Link and Phelan have written more up to date, but arguably equally classic papers about Social Conditions as Fundamental Causes of Disease.

    Selecting doctors from those whose personal experience of struggle is restricted to the sports field or the classroom, who have profited from privilege, who have dropped humanities at an early age and have been kept busy with biology adds to the problems. Interdisciplinary scepticism, verging on hostility is all too common, but social media and blogs like this may be the beginning of more enlightened collaborations


  2. I agree, it is particularly pertinent since physicians are being given greater and greater power (power is also greatly lacking from analyses), they are expected now to be managers and commissioners and researchers as well as clinicians.


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