Causality: Mechanisms Versus Laws
Classical mechanical philosophy approached causality in terms of fundamentally universal, deterministic laws.[133] The new mechanical philosophy understands causality in terms of mechanisms or, rephrasing Mumford's expression, ‘passing around of mechanisms'.[134] Causality works through mechanisms, and precedes and is more basic than laws; in fact, causality by mechanisms brings laws themselves into question.[135]
There are at least two positions regarding laws among the new mechanists.
Firstly, some argue that the abstract general laws of science are descriptions of covariations and relations generally mathematically expressed[136]; They are not causal laws since they do not account for causal mechanisms underlying the covariation or relationship they assert. Causality refers to mechanisms, which are an alternative to laws (Cartwright 1989, 2007a, b; Bogen 2005; Machamer 2004; Glennan 2005 and Andersen 2011). Mechanisms explain laws, and laws are descriptions of regularities.[137]The second position argues that all laws, universal or statistical, are like black boxes which must be opened to reveal the mechanisms hidden inside in order to establish true causal explanations. As Elster (1998) notes, mechanisms are the antonym of laws, but they do not exclude them. Thus, although black box laws are accepted, causality must be investigated by looking at mechanisms. In this respect, Glennan (1996, 49) argues that ‘all but the fundamental laws of physics can be explained by reference to mechanisms (...), a theory of causation according to which events are causally related when there is a mechanism that connects them'. The idea is to make the black boxes transparent; in other words, to identify the causal mechanisms involved. The explanatory strategy is to go from black boxes regularities to mechanisms because what underlies most causal connections are not laws but mechanisms (Glennan 1996, 1997, 2002; Machamer et al.
2000, further MCD, among others).Regularity does not imply causation, even though it may be a powerful reason to expect it, as Little (1991) believes. The deductive-nomological (D-N) explanation is satisfied by assertions of regularities which leave causal mechanisms and processes unspecified. These regularities can be quite stable (Glennan 2002 refers to them as ‘robust sequences’), less stable or even unique (‘unstable sequences’ Glennan 2002).[138] But an adequate causal explanation requires the causal mechanism involved in the observed correlation to be specified. The universal laws of D-N models emphasise prediction; mechanisms emphasise causal explanation.
There is no need to postpone explaining the events of the world until we have knowledge of their laws: according to Cartwright (1983), there may be a covering law including the different factors which together produced an effect, but what is important is that ‘our ability to give this humdrum explanation precedes our knowledge of that law. On the Day of Judgment, when all laws are known, these may suffice to explain all phenomena. But in the meantime we do give explanations; and it is the job of science to tell us what kinds of explanations are admissible’ (Cartwright 1983, 51-52). We have a causal explanation identifying the mechanisms operating in a singular case (for example, the death of Cartwright’s camellias) or in general cases (the tendency for women to be paid less than men for performing the same job).
Explaining an event, therefore, consists of showing where it lies in the causal structure of the world, which involves describing the process through which the mechanism (or set of mechanisms) in question produced it.[139] Thus, ‘it is not surprising that much of the practice of science can be understood in terms of the discovery and description of mechanisms’ (MCD 2000,1-2). Scientific explanation does not consist in logically connect, as in the covering law model, the explanans and the explanandum and thus inferring the latter from the former.
Both positions understand that causality operates through mechanisms; the difference lies in how laws are conceived. For the proponents of one position, laws are never formulated at the level of causal mechanisms: they are inevitably black boxes. For advocates of the other position, black box laws are temporary, existing as such only until the black boxes can be opened to reveal the nuts and bolts that will allow us to formulate the true causal laws of nature. In any case, laws do not constitute a basic ontological category, and ‘when we treat them as such we get a distorted picture of the nature of causal relations’ (Glennan 2010a, 380). Mechanisms can tell us more about causality than laws can.
Below causality in terms of mechanisms will be characterized, starting with a discussion of mechanisms themselves.
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