Abstract
Piccinini and Craver (Synthese 183:283–311, 2011) argue for the surprising view that psychological explanation, properly understood, is a species of mechanistic explanation. This contrasts with the ‘received view’ (due, primarily, to Cummins and Fodor) which maintains a sharp distinction between psychological explanation and mechanistic explanation. The former is typically construed as functional analysis, the analysis of some psychological capacity into an organized series of subcapacities without specifying any of the structural features that underlie the explanandum capacity. The latter idea, of course, sees explanation as a matter of describing structures that maintain (or produce) the explanandum capacity. In this paper, I defend the received view by criticizing Piccinini and Craver’s argument for the claim that psychological explanation is not distinct from mechanistic explanation, and by showing how psychological explanations can possess explanatory force even when nothing is known about the underlying neurological details. I conclude with a few brief criticisms about the enterprise of mechanistic explanation in general.
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Notes
I neglect the parts of their paper where they defend the idea that psychological explanation is not autonomous from mechanistic explanation because I am not clear on the relevant sense of ‘autonomy’. They claim it has to do with an absence of direct constraints from psychology to neuroscience (and vice versa). ‘Direct’ means that there are no limitations or restrictions put on psychological theories from neuroscientific findings (or, again, vice versa). Yet even, say, geology provides direct constraints on evolutionary biology. If the geological story tells us the island split away from the mainland 20,000 years ago, the species we see on that island had better tell an evolutionary story that puts them 20,000 years removed from their kin on the mainland. No one, I take it, thinks there is any sense in which evolutionary explanations are not autonomous from geological ones, though. That is enough reason to view their discussion of autonomy with some suspicion. Explanatory autonomy, in the sense I prefer, is simply the ability to formulate genuine explanations without knowing anything about other, even perhaps related, sciences. From what I say below about the distinctness of psychological explanation from mechanistic explanation, I think it will be clear why I also think psychological explanation is autonomous from mechanistic explanation, as well—at least in the sense of ‘autonomy’ I prefer.
To be clear, it is true that functional analyses do make commitments about there being some part(s) or other which carry out the analyzed capacity. Cummins’ analogy of a production line assumes, for example, there is some place each subcapacity takes within the whole line. But mechanistic explanations require much more detail about those parts, their interactions, and how their coordinated activity is responsible for the explanandum capacity. One must, after all, explain what the mechanism is and how it works. Functional analyses, as they are usually understood, assume no such commitments to depicting the details of the mechanism that produces the capacity in question. See the alternative arguments for non-distinctness below for more discussion of this point.
Not to be confused with ‘mechanism schemas’. Schemas are descriptions of mechanisms that can be more or less complete in their descriptions—vis-à-vis of the parts of the system and their interactions. Sketches are always incomplete models of mechanisms because they include gaps and promissory notes about how the target mechanism works. Progress in building (mechanistic) explanations can thus be measured along something like a sketch-schema-mechanism continuum.
It is worth pointing out that, in some passages, Piccinini and Craver say that “functional analysis, properly constrained, is a kind of mechanistic explanation” (p. 284), or “we argue that they can’t possibly be autonomous in this sense because functional analysis is just a kind of mechanistic explanation.” (p. 290) I am not sure whether this way of construing non-distinctness is consistent with the mechanism sketch interpretation, but I will assume it is for simplicity’s sake.
By ‘confirmed’, I mean something like ‘is sufficiently supported to accept’. Of course Piccinini and Craver could not mean that a psychological model cannot be confirmed in any way except through neurophysiological evidence. Confirmation is, I take it, comparatively cheap. What Piccinini and Craver must intend is that we cannot have adequate reasons for accepting such a theory without having some neuroscience to back it up. In the discussion of the argument below I think this point is relatively clear, but it is probably best to be explicit up front to avoid any unnecessary confusion.
There is also indirect evidence that supports this reading of their argument for non-distinctness:
There are still psychologists who pursue explanations of cognition without concerning themselves with how nervous systems work and philosophers who question whether explanations that incorporate neuroscientific evidence are any better than explanations that ignore neuroscientific evidence. We disagree with each. (p. 285)
Their disagreement seems to show that they believe that psychological explanations that do not include neuroscientific details are not worth much. Combined with their rejection of ‘predictivism’, this quote suggests they think that incorporation of those details is crucial for sorting out acceptable from merely adequate analyses.
Here is a quote from Piccinini and Craver to that effect: “If the connection between analyzing tasks [functions] and components is severed completely, then there is no clear sense in which the analyzing sub-capacities are aspects of the actual causal structure of the system as opposed to arbitrary partitions of the system’s capacities or merely possible causal structures.” (p. 293; original emphasis).
It might be thought that Piccinini and Craver could understand ‘mechanism’ in such a deflationary way that this implication is enough to satisfy the mechanist’s underlying idea. If that is so, then everyone is a mechanist and they are no longer saying anything interesting or substantial. Again, if there is any bite to the mechanist’s position, there must be a much stronger demand on functional analysis than this.
I do not mean to imply that mechanists believe that confirmation of functional analyses originates specifically, or only, from neuroscience. Rather the claim I attribute to Piccinini and Craver is that we can have no reason to accept a piece of functional analysis unless that analysis also includes neuroscientific (i.e., mechanistic) information, that the inclusion of this information is essential for the acceptability of the analysis.
Or so he claims on p. 10 of Baddeley (2007).
I mention the capacity for working memory and effects because Cummins (2000) argues that capacities and effects are the primary explananda for psychological theories.
I focus mainly on using effects to confirm models because of the significance of effects to psychological research. There are, of course, other ways for psychological models to receive important confirmation. Mathematical models are common in psychology, where the goal is to make predictions that are hopefully borne out by the behavioral data. The better the fit of the predictions with the data, the more reason to accept the model that makes the predictions. For issues about whether, say, concepts are native or learned, it is helpful to find isolated tribes of people to see about their behavior.
One objection to this line is that one could imagine sophisticated systems that mimic the incidental effects of other algorithms. Cummins is very helpful again here. Imagine a partial products algorithm that also calculates how long it would take a successive adding machine to arrive at its product, then makes sure it comes up with its own product on that time scale. On behavioral grounds alone, it might be very difficult to arrive at the correct analysis. Yet it need not be impossible. There are potentially ways of disabling the timing part of the partial products machine (through some sort of experimental task) which would reveal its mimicry. And, at any rate, surely considerations of parsimony start to kick in when considering alternative analyses as complex as that envisioned by the partial products multiplier that mimics another algorithm. These responses are enough, I think, to undermine whatever force this objection carries.
The Kaplan and Craver paper takes up the issue of whether neuroscientific explanations, rather than psychological explanations, are mechanistic in nature, but a referee for the Kaplan and Craver paper elicited this comment about the explanatory ambitions of cognitive science which is evidently relevant to the polemical thrust of Piccinini and Craver’s paper.
See, for instance, the first footnote of Kaplan and Craver (2011). They explicitly restrict mechanistic explanation to cognitive and systems neuroscience.
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Acknowledgments
I would like to thank a trio of anonymous referees for this journal for especially helpful comments. I appreciate their close reading of the manuscript greatly, and, of course, claim all responsibility for any remaining shortcomings. I would also like to thank Barry Ward, Jim Lampinen, Jack Lyons, and Daniel Feild for many helpful conversations and criticisms about the topics discussed in this paper.
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Barrett, D. Functional analysis and mechanistic explanation. Synthese 191, 2695–2714 (2014). https://doi.org/10.1007/s11229-014-0410-9
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DOI: https://doi.org/10.1007/s11229-014-0410-9