Building Bridges 2022 Spotlight Series: an interview with Nancy Cartwright MAE

Building Bridges 2022 Spotlight Series: an interview with Nancy Cartwright MAE

Winner of the Hypatia Prize, Nancy Cartwright tells us about her recent work and the role philosophy can play in facing present-day challenges.

About Nancy Cartwright MAE

Nancy Cartwright, Lady Hampshire, is a distinguished and influential contemporary philosopher of science and professor at Durham University (UK) and the University of California at San Diego. She served as the President of the Philosophy of Science Association from 2009-2010. She is a Fellow of the British Academy, a member of the American Academy of Arts and Sciences, a member of the German Academy of Sciences Leopoldina, and a Fellow of the Academy of Social Sciences. She was elected to AE in 2018. Her research focuses on objectivity and evidence and evidence-based policy.

In February 2022, the AE Barcelona Knowledge Hub announced Nancy Cartwright winner of their Hypatia European Science Prize for her outstanding contributions to philosophical research. The award ceremony was held and hosted by the Barcelona City Council, in collaboration with the Academia Europaea Barcelona Knowledge Hub.

The interview

Many congratulations on winning the Hypatia European Science Prize! Your recent work focuses on evidence and its use in informing policy decisions. What drew you to this area of work? Could you give us an overview of your evolving research interests?

“I specialised in maths and physics as an undergrad in the US. The degree also had a big helping of philosophy since I was at the University of Pittsburgh, which had a wonderful philosophy department and a Centre for Philosophy of Science that we undergrads were encouraged to participate in. There, I met both my undergrad teachers of physics and philosophy of science outside the classroom, so I started out thinking of the two subjects as interwoven with each other. I went on to specialise in philosophy of physics but with a side interest in causality and in models.

Unlike almost all my philosophy of physics colleagues, I was not much interested in making sense of the intricacies of high physics theory but far more in how that theory encounters the world itself. So I spent a lot of effort trying to understand the role of conceptual schemes like quantum theory in real-life cases where it was supposed to be the driving force, such as in lasers and superconductors. Seeing how the theory was used and how it had to be brought into dialogue with so much other knowledge—unavoidably so, as far as I can see, even in principle—convinced me that all the domains of science are needed to deal with the real world. Even in principle, it’s not all physics.

Throughout my earlier career I also had a lively interest in the social sciences, which are the (very) poor sister of philosophy of physics within the study of philosophy.  So at the time, it was not a good career specialisation for a young philosopher. But when I was offered the Popper Chair at the London School of Economics (LSE), I felt able to throw myself into the philosophy of the social and economic sciences—I was unlikely to get fired if I failed to come up with any great ideas!

Philosophers have always studied the nature of evidence, so it was a natural interest of mine within the philosophy of the natural and social sciences. I took up the topic in a serious way when I was asked to serve on a US National Research Council committee that was looking at ‘Evidence for Social Science and for Social Policy’, at a time when the call for randomised controlled trials (RCTs) was spreading throughout the social and economic sciences. When serving on that committee, I came to see that the standards and types of evidence, and especially the kinds of background assumptions that turn data, facts, observations and experimental results into evidence for hypotheses are generally very different if the hypotheses are the kind we expect to find in ‘pure’ social science rather than the kinds of claims we need for policy prediction and evaluation. I argued for this so vehemently at the meetings that the first committee was followed by a second National Research Council committee on ‘The Use of Scientific Knowledge’. I thereafter threw myself into this issue, since I believe firmly in the possibility of scientific knowledge in both the natural and social sciences but am equally concerned that we learn how to get the kinds of knowledge we need to change the world and how better to use this knowledge to good ends.”

Your current work for the project ‘Knowledge for Use’ investigates how to put scientific research and common knowledge together to build more decent societies. What has the project uncovered? What impact has this project had?

“This was a 5-year EU-funded project, with a largish team. It achieved a number of (what we hope are) useful results on various sub-themes and in six different case study areas. These ranged from international HIV-AIDs policy, to UK and Irish child protection policy, to a study of a joined-up programme in Greater Manchester (UK) to help people get out of depression and to get and maintain employment.

On general topics, we observed that the call for objectivity in establishing and using knowledge claims is far more demanding when research is to be used directly to intervene in the world. We developed and defended the concept that originated with our Venice project member Eleonora Montuschi, of objectivity to be found, which is so-called to underline that when research is to be put to use to affect the world, it is not enough to adopt pre-set methods to satisfy pre-set aims. Instead, you are called on to find the right methods to achieve the rightends in the right way, in the context of use. This is especially demanding. Firstly on the methods side, because methods must be chosen to fit both the problems to be solved and the tools and knowledge available to solve them. Secondly on an the aims side, because determining what the right aims are and the right way to satisfy them can never be properly stated explicitly and requires judgment to figure out. This is a topic I will take up in my Hypatia lecture.

We also did a major study of the uses and misuses of randomised controlled trials (RCTs), which are widely advertised in evidence-based policy venues as the ‘gold standard’ for evidencing causal claims. In particular we offered advice on the vexed notion of ‘external validity’—what more information, and of what types, does it require to use the kind of knowledge about average results in a trial population that can be reliably estimated in a well-conducted RCT, to then help inform us about what might happen in other populations or for specific individuals?

We also did a major study of the use of ‘mixed methods’ to evidence causal claims, with an approach that was different from the standard. The usual tactic is to use a mix of different methods to triangulate in on the same ‘overall’ causal claim, for instance of this form:

‘Policy W implemented via procedures X will produce effects Y in context Z’.

We built from the observation that the cause W and the effect Y are generally far apart in time and maybe place; if W is to lead to Y it will be via a number of intervening steps and Y is only to be expected if each of those steps occurs in turn. So you need evidence that each of those steps can occur, which in turn calls for evidence about how the cause at each step will operate to produce the next step, what support factors are necessary for it to do so, what might happen to derail it, etc. That immediately brings in the need for a huge toolkit of different kinds of methods to get evidence about these very different kinds of things. This in turn led us to develop a new, highly-detailed template for what a ‘theory of change’ for how a policy is to achieve its effects should look like, which makes apparent the role that the various pieces of evidence play and makes an evaluation much easier of what the evidence indicates all told.”

What contribution can philosophy make to face present-day challenges?

“Philosophy has a great deal to offer, millennia of thought on important issues like justice, evidence, objectivity – but primarily by working in consort with other disciplines and knowledge and practice sources. That’s usually called ‘applied philosophy’. But I think the term is misleading, suggesting that we in philosophy devise our theories from careful thought and analysis and our embedment in the everyday and scientific worlds, then bring these theories to derive what they say about concrete cases:

‘What does our favourite theory of justice say is a just distribution of Covid risk in Spain, across different generations and differently abled people?’ Or,

‘What does our favourite theory of evidence say about the claim that randomised controlled trials (RCTs) are the gold standard for causal claims?’

I just can’t see that it could ever work like that. This is like my claim about physics and lasers. Even God could not derive from even the best ultimate theories in physics how a laser works. I think God, like us, would have to use facts from physics along with great dollops of facts that lie well outside the domain of physics to build an understanding of the laser. Similarly I think we have to use the ideas and skills we learn in philosophy in a joint effort with the ideas, skills and practices of many many other domains, including common sense and a feeling of compassion if philosophy is to contribute to present-day challenges.”

What’s next for your work – what are your priorities and ambitions for your research?

“I’d like my research to inspire a cohort of bright, committed young philosophers to work seriously with other knowledge bases to try to ameliorate real-world problems, and I’d like what I do to be solid enough that others think it is worth working with philosophers.”

Interview by the Academia Europaea Cardiff Knowledge Hub. Posted 27th October 2022. For further information please contact

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