by Testing causal explanations in economics Third, explanations fail by question (3.1) [“are the factors cited as possible causes of an event in fact aspects of the situation in which that event occurred?”] where the factors invoked as possible causes are idealisations. No doubt this claim will be considered contentious by some economists, accustomed as they are to explanations based on such dramatic assumptions as rational expectations, single-agent ‘economies’, and two-commodity ‘worlds’. The issue here turns on the distinction between abstraction (passing over or omitting to mention aspects of the causal history) and idealisation (invoking entities that exist only in the realm of ideas, such as most limit types and what Maki (1992) calls ‘theoretical
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Testing causal explanations in economics
Third, explanations fail by question (3.1) [“are the factors cited as possible causes of an event in fact aspects of the situation in which that event occurred?”] where the factors invoked as possible causes are idealisations. No doubt this claim will be considered contentious by some economists, accustomed as they are to explanations based on such dramatic assumptions as rational expectations, single-agent ‘economies’, and two-commodity ‘worlds’. The issue here turns on the distinction between abstraction (passing over or omitting to mention aspects of the causal history) and idealisation (invoking entities that exist only in the realm of ideas, such as most limit types and what Maki (1992) calls ‘theoretical isolations’). This distinction cannot be pursued here, but the general idea is that although every explanation involves abstraction insofar as we can never provide a complete list of the causes of any event, no genuine attempt at causal explanation can invoke as causes theoretical entities that have no existence other than in the minds and discourse of scientific investigators. For such entities cannot be aspects of real economic situations and are therefore ineligible as candidate causes. Explanations that invoke such entities therefore either fail, if offered as causal explanations in the sense I have described, or should be thought of as something other than causal explanations.
When it comes to modelling, yours truly does see the point often emphatically made for simplicity among economists and econometricians — but only as long as it doesn’t impinge on our truth-seeking. ‘Simple’ macroeconom(etr)ic models may be an informative heuristic tool for research. But if practitioners of modern macroeconom(etr)ics do not investigate and make an effort of providing a justification for the credibility of the simplicity-assumptions on which they erect their building, it will not fullfil its tasks. Maintaining that economics is a science in the ‘true knowledge’ business, yours truly remains a skeptic of the pretences and aspirations of ‘simple’ macroeconom(etr)ic models and theories building on unwarranted idealisations. So far, I can’t really see that e. g. microfounded macromodels have yielded very much in terms of realistic and relevant economic knowledge.
All empirical sciences use simplifying or unrealistic assumptions (abstractions) in their modelling activities. That is not the issue – as long as the assumptions made are not unrealistic in the wrong way or for the wrong reasons.
But models do not only face theory. They also have to look to the world. Being able to model a ‘credible world,’ a world that somehow could be considered real or similar to the real world, is not the same as investigating the real world. Even though all theories are false, since they simplify, they may still possibly serve our pursuit of truth. But then they cannot be unrealistic or false in any way. The falsehood or unrealisticness has to be qualified.
Explanation, understanding and prediction of real world phenomena, relations and mechanisms therefore cannot be grounded on simpliciter assuming the invoked isolations to be warranted. If we cannot show that the mechanisms or causes we isolate and handle in our models are stable, in the sense that what when we export them from are models to our target systems they do not change from one situation to another, then they only hold under ceteris paribus conditions and a fortiori are of limited value for our understanding, explanation and prediction of our real world target system.
The obvious ontological shortcoming of a basically epistemic – rather than ontological – approach, is that the use of idealisations tout court do not guarantee that the correspondence between model and target is interesting, relevant, revealing or somehow adequate in terms of mechanisms, causal powers, capacities or tendencies. No matter how many convoluted refinements of concepts made in the model, if the ‘simplifying’ idealisations made do not result in models similar to reality in the appropriate respects (such as structure, isomorphism etc), the surrogate system becomes a substitute system that does not bridge to the world but rather misses its target.
Constructing macroeconomic models somehow seen as “successively approximating” macroeconomic reality, is a rather unimpressive attempt at legitimising using fictitious idealisations for reasons more to do with model tractability than with a genuine interest of understanding and explaining features of real economies. Many of the model assumptions standardly made in mainstream macroeconomics are restrictive rather than harmless and could a fortiori anyway not in any sensible meaning be considered approximations at all.
If you — to ‘save’ your theory or model — have to invoke things that do not exist , well, then your theory or model is probably not adequate enough to give the searched for causal explanations.