What is a nomological machine?
– Nancy Cartwright, The Dappled World – A Study of the Boundaries of Science
In a simple, concise, and pithy definition Nancy Cartwright answers her own question, saying: “It is a fixed (enough) arrangement of components, or factors, with stable (enough) capacities that in the right sort of stable (enough) environment will, with repeated operation, give rise to the kind of regular behavior that we represent in our scientific laws”.1
In reading this sentence again we get the feeling that Nancy is not quite as sure of all the required needs of her statement to enact the production of these laws that it supports. With the use of “enough” as “moderately, fairly, tolerably” (good enough) in several places we get the feeling of an unwritten complicit statement that this is all based on a notion of heuristics which refers to experience-based techniques for problem solving, learning, and discovery that give a solution which is not guaranteed to be optimal. Where the exhaustive search is impractical, heuristic methods are used to speed up the process of finding a satisfactory solution via mental shortcuts to ease the cognitive load of making a decision.
Then her use of the terms “fixed arrangement of components, or factors” situates this within experimental sciences. An experiment is an orderly procedure carried out with the goal of verifying, refuting, or establishing the validity of a hypothesis. Controlled experiments provide insight into cause-and-effect by demonstrating what outcome occurs when a particular factor is manipulated. Controlled experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results. There also exist natural experimental studies.
The next aspect is her statement “with stable (enough) capacities”. What is a capacity? In her work she tells us that she started out asking the question “Where do the laws of nature come from?” As she tells it for most of us this might be a “queer question to a post-logical-positivist empiricist,” that the laws of nature are basic to our understanding, and that other things come from, happen on account of, them (49). But she rejects this common sense notion and instead follows Rom Harre in eliminating this story in favor of one in which instead of laws as being basic, capacities are the basis from which laws “obtain – to the extant that do obtain – on account of the capacities; or more explicitly, on account of the repeated operation of a system of components with stable capacities in particularly fortunate circumstances (49). This notion of capacities as the basis of laws comes in two flavors: naturally and engineered. Kepler’s observation of the laws governing the motion of planets is natural, while laws discovered through controlled laboratory experiments are engineered.
Now my only question before continuing is “What are capacities?” I did not see any clear cut definition of this in her text so in search of a clarified definition of this term and her modification of it in her own work I discovered another work of hers Nature’s Capacities and Their Measurement. I do not have a copy of this work at present but was able to read the preface extract luckily. In it she presents the basic thesis that “science is measurement; capacities can be measured; and science cannot be understood without them”. More specifically she tells us that the third thesis could be simplified to: capacities are real. What Cartwright is arguing is that statiistical probabilities can provide evidence for causal connections only if the probability of the effect given the presence of the putative cause-factor is higher than the probability of the effect given its absence in all those populations that are homogeneous with respect to all other causal factors. We need to know both what all these other causes are and that they are not operating at this point in time before we can use statistics to measure causes. As Cartwright puts it, ‘no causes in: no causes out’. And this is why what she is saying is so radical – not only must knowledge of these causes come from sources other than statistical data, but once they are known and known not to be operating then statistical data becomes an irrelevance as what the cause is will be obvious – it will be the variable that is left over.
All of this would lead me far afield, but the one thing to note is that Cartwright is bucking the standard orthodoxy in that she holds to the view that powers are real. A return to some of the Aristotelian traditions seems to be surfacing in her work as seen by her inclusion with several other realists of powers, dispositions, capacities in Powers and Capacities in Philosophy: The New Aristotleianism edited by John Greco and Ruth Groff. I know that George Molnar in his Powers: A Study in Metaphysics was moving in this direction. Stephen Mumford in his Dispositions and recent Getting Causes from Powers offers another version. (Make a mental note to self: read these!) As she states it in her essay in this volume: “Aristotelian powers, we maintain, are part of the basic ontology of nature— at least as nature is pictured through the lens of modern science. We defend these powers not on general metaphysical grounds but rather show their importance for making sense of contemporary scientific practice”.2
Of course the orthodoxy that she is attempting to circumvent is the whole tradition stemming from Hume and the Empiricists. As Mumford in his preface to Molnar’s work tells us “Empiricists argue that there is just no need to invoke a separate category of powers in addition to categories such as events and their categorical (non-power) properties. If there is nothing more to the ascription of a power property than asserting the truth of a conditional, and that conditional mentions only events with their categorical properties, then power ascriptions can be reduced away into non-powers. Carnap (1936-7) had argued this line, though the precise form of his `reduction sentences’ needed some refinement. Ryle fell into the same category and was a defender, if anyone was a defender, of the `naive’ conditional analysis. In contemporary metaphysics, David Lewis (1998) has been the chief advocate of the Humean view and he has tried to show that, although the naive conditional analysis has problems, a reformed version is tenable that preserves its Humean spirit”.3
Returning to our theme: nomological engines. John Pemberton tells us “Nomological machines produce the causal relations they do because of the way the exercisings of the various causal powers involved combine in the context of the machine to produce changes in the machine arrangement” (Powers and Capacities in Philosophy,Kindle Locations 2128-2129) . He continues:
Central to our account is taking change to be a coherent process that unfolds through time. Here, too, we side with Aristotle, in opposition to both Hume and more recent writers who take change events to be adequately characterized by their start and end points alone.
We shall show how causal relations arise out of the operation of a nomological machine. This makes clear why a good account of the machine that would give rise to a hypothesized causal relation can provide strong evidence for that causal relation. We explicate how the machine arrangement dictates what can happen— it has emergent powers which are not to be found in its components.
It might be objected that the account of powers we offer does not eliminate the need for laws of nature since it still leaves need for rules of combination that are independent of the powers in nature. So that unlike some other powers accounts, we may not have succeeded in getting governance back in to nature. We concede that this may be so. There may be ways to get rules for combining powers into nature itself in a way that fits a pure powers ontology and there may not. This remains work for the future.(Kindle Locations 2145-2148).
Nancy Cartwright in the original essay tells us this about capacities and their relation to laws argues against laws that are unconditional and unrestricted in scope. For here laws need nomological machines to generate them, and hold only on condition that the machines run properly. As she tells it “I say that our understanding of these [nomological machines] depends on knowledge of capacities, not knowledge of laws. Is there much, after all, difference? I think so, because when we refuse to reconstruct our knowledge as knowledge of capacities, we deny much of what we know and we turn many of our best inventions into pure guesses” (ibid. 59). As she further states:
What is important about capacities is their open-endedness: what we know about them suggests strategies rather than underwriting conclusions, as a vending-machine view of science would require. To see the open-endedness it is useful to understand how capacities differ from dispositions (59).
To understand this difference between capacities and dispositions would lead me into the Gordian knot of contemporary metaphysics with all its current debates. I may tackle that at some future time, but not now. Hopefully I’ve shed light on what a nomologica machine is. I should add examples of this, but if you are interested she provides ample coverage in her book so I’ll refrain from that, too, at this time.
1. Nancy Cartwright. The Dappled World – A Study of the Boundaries of Science. (Cambridge University Press, 1999)
2. (2013-01-25). Powers and Capacities in Philosophy: The New Aristotleianism (Kindle Locations 2112-2114). Taylor and Francis. Kindle Edition.
3. the late George Molnar. Powers: A Study in Metaphysics (p. 2). Kindle Edition.