I suspect that I would not have made it through my PhD without the institution pictured below:
During “Fall” 2006, when I was a Visiting Fellow at the above-pictured bus’s destination, Pinnochio’s was my lunchtime sustenance, the thing I looked forward to all morning as I sat in the library of the Philosophy Department wondering whether the debate between Stalnaker and Lewis on counterfactual excluded middle had any bearing on Schaffer’s contrastivist treatment of causal selection.
But wait: when I say that I would not have got through without Pinnochio’s, what exactly am I envisaging? A situation where Pinnochio’s was there but I never discovered it? A situation where it had never existed? –or where perhaps it closed just as I found it, like my second favourite, Burritos? (I still sometimes wonder what might have been.) Or perhaps a situation where Pinnochio’s existed, but didn’t do such good pizza; pizza such as this:
It is interesting to be back in the same place thinking about the same questions ten years later, and satisfying to have come quite an unpredictable route, both intellectually and geographically. In 2006 I had never heard of epidemiology, much less contemplated working on it; and when I got into epidemiology, I thought I had decided to move away from working on counterfactuals and causation. It is curious how things turn out.
I am here for a Radcliffe Institute workshop mostly centering around an upcoming special issue of the International Journal of Epidemiology on causal inference. Previously I posted links to papers in IJE earlier this year, and the special issue promises to be really interesting–a real resource, for sociologists, philosophers and perhaps historians, as well as for epidemiologists.
On the long journey from Johannesburg to Boston I read or re-read as much as I could of what has been published or written on this during 2015 and 2016. I can see some real progress. It is clear that nobody intends to restrict causal claims to those that can be relativized to a humanly feasible intervention, for example. It is also clear that at least some of the debate concerns matters of presentation. It is important to me, for example, not to be cast as a methodological Luddite who insists on putting verbiage in the way of honest, hardworking methodologists who just want to get on with the job. It is important to those methodologists, on the other hand, not to be cast as any sort of methodological fascist, intent on forcing everyone to employ a preferred set of methods, and excommunicating everyone else.
On the other hand, serious questions remain. From what I have read, the main ones are as follows.
- What exactly are the commitments of the Potential Outcomes Approach? Is it just a set of methods? Or something more? And if more, exactly what? I have been trying to understand this since I first started working on the topic, and in the latest paper by Vandenbroucke, Pearce, and myself, we try to set the elements of the position out. I will be hoping to find out if we got it right.
- The distinction between causal identification and quantitative estimation of effect size has become central. Does it bear the weight that is put on it? Does it indeed offer a domain in which the POA really can delineate either necessary or sufficient (or both) conditions for a causal inference? How are identification and estimation related?
- Are there sufficient conditions for causal inference, of any kind, and if so what kind of sufficiency is it?
- What exactly is the role of judgement? Everyone agrees it is needed. But what exactly is it, and how is it to be trained, if formal methods do not take us all the way? Although I am always pushing on the need for judgement, I have great sympathy with the formalising perspective. After all, judgement isn’t magic. If we can do it, there must be something we are doing; and if we could only describe this, we could automate it, refine it, improve it, and so forth. Yet we can’t even say what it is we are doing when we make a causal (or other inductive) inference. How can this be? An old question, obviously, but one that I think is becoming more pressing in the age of technicality.
- What is the broader significance of the developments of the last ten years that fall under the POA? Are they part of the development of the science towards what Kuhn would call puzzle-solving? Part of the appeal, if not the motivation, of the new methods seems to be a desire for formalising causal inference. Is this reasonable? Achievable? Healthy or not? Kuhn’s view is that scientists learn by rote, and in order to learn by rote there needs to be something to learn. A methodology that says “think about it and use your judgement” does not lend itself to this. Are these developments partly about getting epidemiology into a “normal science” phase? Of course we don’t have to believe Kuhn was right about science, but I continue to find his lens useful.
- What is the social and political dimension to this debate? Will the new methods render difficulty variables like race more tractable? Or will the POA enforce a certain view of them, perhaps by encouraging us to think of race as a genetic trait and not as a complex socio-historical role? Further (and this hasn’t been explicitly asked, but it occurred to me on reading) does the development of a set of methods for measuring effect sizes of interventions in increasingly difficult situations reflect the social and political interests? — certainly not of the methodologist in question, of course; I mean the larger context in which this sort of project is undertaken at Ivy League universities, gains traction, gives rise to intellectual celebrities, and so forth.
The last question in particular is uncomfortable, since it sounds unpleasantly personal. It really isn’t personal; it is not any sort of attack, and indeed it extends to this very debate, and to myself.
The two churches between my Sheraton and Pinnochio’s have signs outside saying “BLACK LIVES MATTER”. A helpful reminder, since I didn’t see many black people on my walk. Most of those I did see appeared to be homeless, so the signs must be quite affirmative for them. The other diners at Pinnochio’s were all white men: two professors having a long conversation about a running conflict with an absent colleague, and three students probably still in their teens, two of whom were in suit and tie. I think they were choristers. I was feeling right at home, until one of the youngsters said to another, “How many suits do you have?”
After a pause, the other said “Six or seven.” The way he said it I could tell he had at least twelve.
I have three, only one of which both is clean and fits me.
Had I not discovered Pinnochio’s ten years ago, perhaps two of them would fit me.