Causation with a Human Face: Normative Theory and Descriptive Psychology

This superb book should help set the agenda for philosophical work on causation for years to come. Indeed, its impact deserves to be felt more widely: philosophers who don't give a fig about causation will still profit a great deal by studying this book closely. It is not faultless: in particular, Woodward's treatment in chapter 2 of his favored "interventionist" account of causation and its alternatives may leave the uninitiated reader lost. That said, these defects do nothing to undermine the main philosophical achievement of the book, which is to articulate, defend, and provide detailed illustrations of the power of a certain methodological orientation to the philosophical study of causation that Woodward calls the "functional approach."The word functional signals that the questions that should be of primary concern to the philosophical study of causation are questions, roughly, about the function—point, rationale, goal-serving capacity—of our concept of causation, along with corresponding questions about the kinds of worldly structures this concept answers to. (We'll see shortly that, for reasons Woodward expertly lays out, talk of "our concept" of causation is too limiting. But if you're a philosopher new to Woodward's approach, it's probably the best way to start to orient you.) Chapter 1 lays out the functional approach in the abstract, paying special attention to the ways in which it involves weaving together descriptive and normative inquiry into human causal cognition. Chapter 3 draws out a number of specific and important lessons for how inquiry into causation ought to proceed, given the functional approach; along the way, it patiently constructs devastating challenges to standard ways that philosophers rely on "intuitions" about cases, while at the same defending importantly different ways in which such intuitions can help guide inquiry. Together, these chapters are a methodological tour de force. Summarizing them adequately isn't possible here. What I'll do instead is to approach the main ideas obliquely, by considering a way that philosophical dialectic about causation could, but typically doesn't, proceed.Suppose I advance a simple Mackie-style analysis of causation: event C is a cause of event E iff (1) C and E both occur; (2) C precedes E; and (3) there is some true proposition P about the circumstances in which C and E occur such that the conjunction of P, the proposition that C occurs, and the proposition L that captures the fundamental laws entails the proposition that E occurs, but the conjunction of P and L alone does not. A nonstarter! After all, it's child's play to produce cases where C and E meet these conditions, but where intuition judges C and E to be joint effects of some common cause. In short, this analysis conflates causation with common-cause-induced correlation, and so must be rejected. Maybe we add bells and whistles to fix the analysis; maybe we try something completely different. But either way, the analysis as it stands has been refuted.What I've just described is, I trust, an utterly familiar example of how philosophical back-and-forth proceeds (and not just when the subject is causation). But now consider a kind of thought experiment rarely entertained in these dialectical contexts: Imagine a community of people whose concept of causation was exactly captured by this analysis. So they don't see any distinction between what we call "causation" and what we call "common-cause-induced correlation." What, if anything, would be wrong with them? Put another way, why not adopt their way of thinking about causation? Those are the kinds of question Woodward thinks we should be asking. I think he is dead right.Note that to answer such questions well, we have to set aside the temptation to pound the table and say things like "They wouldn't really be thinking about causation; that's what's wrong!" Woodward gives a thorough and conscientious airing (in chapters 1 and 3) to similar kinds of philosophical moves and, to my mind, decisively shows how unproductive they are. What he offers instead is a program for addressing these questions by integrating different kinds of inquiry, some more empirical and some more philosophical. Adapting his own description (151) somewhat: (1) We need a clear understanding of the structure of human causal cognition, one that highlights its most important and central features and explains how these features subserve such things as decision-making and strategies for learning.(2) We need a clear formulation, at the right level of abstraction and generality, of goals whose achievement is plausibly enabled by the ability to engage in causal cognition with the features described in (1) (for example, the goals of manipulating, predicting, and controlling aspects of the world around us).(3) We need a kind of empirical-cum-normative analysis of how and why different features of causal cognition contribute to achieving the goals described in (2).(4) In pursuit of (3), we need an account—again, at the right level of abstraction and generality—of the kinds of worldly structures (for example, structures of interventionist counterfactual dependence) that human causal cognition is responsive to.(5) We need a clear understanding of why (and to what extent) achieving the goals described in (2) is worthwhile—why, in Woodward's words, achieving them counts as a kind of "success."Returning briefly to our thought experiment, I think we can see, dimly but well enough, that if the goals in (2) at least include those Woodward consistently highlights—prediction, manipulation, and control—then our imaginary humans will do quite badly at using what they recognize as information about the causal structure of the world around them as a basis for manipulating and controlling their world. But the point of the thought experiment is really to get us to think harder and more productively about non-imaginary humans, and the complex interrelationships between the structure of human causal cognition, the structure of the world, and core sources of human value.Woodward's articulation, defense, and illustration of this program is so rich and sophisticated that I can only hope to highlight a couple of key points. First, the kind of inquiry Woodward is urging philosophers of causation to engage in is necessarily interdisciplinary. All of it? Can't the understanding described in (1) be achieved just by empirical psychology? In practice, no: as chapter 4's well-curated review of results from the empirical psychological literature demonstrates, philosophical inquiry has played a crucial role both in generating hypotheses worth testing and in developing conceptual frameworks that permit the formulation of such hypotheses. (We might add that what counts as "important" or "central" can't exactly be settled by experiment.) On the flip side, even inquiries like (5) will require close attention to empirically discoverable limitations on human causal cognition, lest we propose "from the armchair" goals that, however desirable, only angelic causal cognition could achieve.Second, you may have noticed the shift from talk of "our concept" of causation to talk of "human causal cognition." Here I am following Woodward's lead: he argues persuasively that focusing exclusively on what is part of, or involved in, "our concept" of causation will lead us to overlook features of causal cognition of vital importance. Woodward's working example is invariance: roughly, the extent to which a given causal relationship holds across a wide variety of actual and possible circumstances. Chapter 5 provides a detailed philosophical exposition of invariance; chapter 6 insightfully applies this discussion to a range of well-known examples from the philosophical literature, including (my favorite) puzzles about double-prevention; chapter 7 walks the reader through a series of fascinating empirical studies that help bring out the role of invariance in causal cognition. These chapters make a compelling case that, from the perspective of Woodward's functionalist approach, cognitive strategies for tracking and attending to different kinds of invariance are a very important part of human causal cognition. As just one example, chapter 5 ends with a brilliant discussion comparing invariance as a goal of inquiry with "explanatoriness" as such a goal; this passage should be required reading for any philosopher interested in "inference to the best explanation." But as Woodward notes, invariance does not seem to matter to the traditional philosophical task of analyzing our concept of causation, as witness the ease with which we can construct examples in which it is "intuitively clear" that C causes E, but where this causal relationship is highly non-invariant. So much the worse for letting "our concept" delimit the boundaries of inquiry into causation. Chapter 8 closes out the book with some more tentative—in part because largely empirically untested—hypotheses about the importance to causal cognition of the concept of "proportionality" between cause and effect.Chapter 2 surveys philosophical theories of causation, devoting the most space to the "interventionist" approach Woodward favors. This chapter is the one weak spot in the book; readers not already at least somewhat familiar with contemporary philosophical debates about causation may find it more confusing than helpful. The treatment of rival views is oddly selective: for example, regularity theories of causation need not presuppose (as Woodward seems to suggest) a regularity theory of law; and one can pursue a Lewis-style counterfactual account without adopting Lewis's peculiar semantics for counterfactuals. The treatment of interventionism doesn't alert the reader to a range of important critiques in the literature. Finally, the distinction between "type-causal claims" and "token-causal claims" that the chapter begins with—and that is crucial to understanding the target of inquiry for the functional approach—never comes into focus sharply enough. The upshot is that "novice" readers would be well advised to augment chapter 2 with some well-chosen Stanford Encyclopedia of Philosophy articles and perhaps a foray into the literature critical of interventionism.Still, some perspective: while the problems in chapter 2 create a kind of barrier to entry, they in no way undermine the impressive case Woodward makes for his functionalist approach. My own view, to put it bluntly, is that philosophers working on causation should just stop doing the kind of thing Lewis taught us to do, and devote their energies and talents to pursuing the functionalist program instead. More: one thing that makes the functional approach so genuinely thrilling is the prospect of applying it to other topics. Woodward mentions a few in passing: "knowledge," "free choice," "morally responsible" (34–35). (Parroting our earlier thought experiment, we might productively ask what would go wrong for a community of people whose only knowledge-like concept just was the concept of justified true belief.) Like Woodward, I suspect the list could be extended both considerably and profitably, and the reason I hope this book gets read very widely within philosophy is precisely so that the invitation Woodward extends gets taken up: "I see what follows as a sort of testing ground, in connection with one particular set of concepts, of the merits of [the functionalist] approach" (35). In my view, these merits are not just considerable but game-changing.