This is the Challenging Neglect podcast series. I’m Erman Sozudogru and I’m Samantha Vanderslott. We’re two PhD students from the Science and Technology Studies Department at UCL. Today we’re joined by Alex Broadbent, who’s a philosopher of science in University of Johannesburg in South Africa. Alex’s work on philosophy of epidemiology and causation in sciences, so Alex is the author of many papers on these topics, and he recently published his book, Philosophy of Epidemiology. Today, we are going to talk about neglected tropical diseases and how they play a part in his research, so welcome, Alex.
So, can you tell us a bit more about your research in general on Philosophy of Epidemiology, and then we can later on talk about how neglected diseases play a part in your research?
Sure, so I’m a Philosopher of Science by training, and I initially had no particular interest in epidemiology. I just… I kind of just stumbled across it and I sort of thought that, as philosophers sometimes do, you know, I’d be able to say a few useful things and then get on with doing some serious philosophy, and I just basically discovered that I was totally wrong.
There are lots of very interesting things that get thrown up when you start to look at a science in detail, and particularly a science like epidemiology, which is different from other sciences in lots of ways and have lots… is very important, socially important. It’s important to obviously population health and so forth, and I just found myself getting, rather than just spending a few months writing a paper, I found myself getting further and further drawn into thinking about it.
I guess I’m sort of driven by an underlying idea that philosophers could do more to make the work useful in the broadest sense of the word, useful, so, yes, that’s really where I come at it from.
Was there a particular paper that you’d seen or someone that you’d met that drew you towards epidemiology, in particular?
Well, there’s a chap called Robin Zimmin who runs a foundation in Cambridge called the PHG Foundation, which is a sort of a private… PGH stands for Public Health Genomics, and he basically got me into it. He just suggested I do it when I finished my doctorate so he can take the credit for that.
In terms of papers, what I noticed is there are papers by epidemiologists, for example, there’s a famous paper called Causes, by Ken Rothman, in 1976, which basically almost exactly reinvents a theory of causation, published not long earlier, by a philosopher called Jonathan Mackie, and it just made me think there’s clearly some overlap here.
You know, you’ve studied this… and what you study, you know, you train as a philosopher and you encounter some theory of causation in that context, and then suddenly, from a completely different angle, you see somebody else come with a fairly similar idea, apparently independently, and that’s quite striking and it suggests that there’s an overlap.
I think this is quite a good point to get into your idea that you published in your 2009 paper, where you show us the contrasted model you support, you put this across in causation and models and disease and epidemiology, and if you can tell us a bit more about where your ideas came from, and how this fits into the wider context of the causation research.
Well, the thought there… I mean what struck me is… I mean my doctoral work was on causation, and I started… when I got into the thinking about epidemiology, I looked at… naturally looked at all the stuff that epidemiologists have written about causation, and there’s quite a lot. And then what I realised is that actually a lot of what was being said about causation was sort of things like, you know, diseases are multi-factorial or diseases have many causes and I suddenly realised that actually the discussion wasn’t really about causation even if people thought it was.
What it was really about, was about how one classifies diseases, and classification of any domain is another huge philosophical topic, but the reason causation was being focussed on, is that the traditional way since the 19th Century, of classifying diseases was by classifying them by their causes, and that works very well for certain kind of diseases. It just seems to be very fruitful, so infectious diseases, there seems to be a single cause that’s present in every case of the disease and absent otherwise.
But there’s no empirical evidence that you can bring to bear that forces you to classify diseases by their causes even for those ones, and for some, for sort of the diseases that a lot of epidemiology’s interesting in, that just doesn’t seem to be so useful. I mean things like cancers and diabetes and so forth. It doesn’t seem that there’s just one or even just a particular bundle of causes. So, the move in modern epidemiology has been away from that and towards multi-factorialism, so you sort of think okay, a disease is a kind of, you know, a case of disease has many causes and it… no particular, there’s no signature pattern of causes for a hidden disease according to which you can classify disease.
And I… and what concerns me about that is if you go that way, you basically drop all the successes that came along with the older way of thinking about disease; the successes of, for example, vaccination, all this sort of thing, the idea that if… you can only identify that a cause that’s present in every case of disease and you can intervene on that, take it away and you get elimination of a disease, and so yes, so the contrasted model is supposed to be a kind of attempt to preserve some of the plaint of the older way of thinking about diseases, and preserve the idea of classifying diseases by their causes, but allow that diseases might have more than one cause, or more than one classificatory cause.
Every event has more than one cause in some sense. It’s find a way where you can still classify diseases according to their causes, but allow you to classify them according to a bundle of causes and not just one, so in that sense it’s actually quite a simple idea that it’s… but, yes, that was the point of that paper.
And do you also think the idea of causation is integral to epidemiology as a discipline, so thinking more widely really?
I do, yes, I do think it’s integral to epidemiology as a discipline. I mean some epidemiologists have suggested that actually maybe it’s not that important, and at the moment actually, there’s a move, sort of hot stuff in some area that epidemiology at the moment is what’s potential outcomes models, where people say we don’t need to worry about causation. All we need to worry about is basically what would happen if we did this and you know, you build these models where you say okay, if this changed, then that would change, counter-factual models or potential outcome models.
But I think that actually causation is… you know, the concept is pretty deeply embedded in the whole point of doing epidemiology. I mean epidemiologists don’t want to just find out whether eliminating smoking will reduce the incidence of lung cancer. They want to know whether smoking causes lung cancer, so I think it is a pretty deeply embedded.
There my question would be regarding the social causes for the diseases. How much epidemiology hosts that notion of socially caused disease like obesity, etc?
Epidemiology, I think, as a discipline is very open to there being social causes of disease, and there are some epidemiologists who, you know, individual epidemiologists might vary in their attitudes and their level of scepticism about those, such candidate causes of that kind, but fundamentally it’s, you know, epidemiology is… I think it’s… arguably; it’s a social science rather than a natural science.
I mean it’s… so, it is going to be open to… in principle, it’s open to there being social causes of diseases and social, you know, the social determinants of health. I mean the whole social determinants of health. I mean the whole social determinants of health movement has its roots in epidemiology, so… and you know, the classic, sort of… many of the classic episodes in epidemiology involve trying to tell whether the cause of the disease is, you know, is poverty or is something else, and the discovery of Vitamin D, for example, in 1920s was… came about because this guy was trying to figure out whether this disease that afflicted… apparently afflicted very poor cotton farmers in the South of America, whether that disease was just the result of them being poor or was a the result of something else.
I think that’s given a very good background about your interests in epidemiology. Was that also how you became interested in NTDs, neglected tropical diseases?
Yes, the neglected tropical disease thing came out of a symposium at the Brocher Foundation, Switzerland I was asked to come and talk in, and that was back in… originally that was back in 2008, and then this paper came out of that. Yes, I mean the thought there was, again, to try and link… you know, try and do something useful with all the sort of conceptual stuff that philosophers, you know, spend all this intellectual energy on, and actually try and, you know, deliver something, you know, in some potential theoretical way down the line, you know, useful in some way.
So, what I was trying to do was, I was trying to… because I had already been thinking about the definition of disease, I tried to think about the definition of neglected disease, neglected tropical disease and about all the components, and basically in the paper, I break it down and I think about, you know, the tropical bits, the neglected bits and the disease bits.
I guess your idea about the, you know, defining neglect, not according to the amount of money that goes into research basically, research and development, but looking at it from a, you know, more sophisticated way, has an impact, not just, you know, within our understanding of… well, it has an impact on our understanding, but this impact on understanding should really help the scientists about, you know, finding the cures for diseases and I… one thing that I can think of is current interest in finding anti-parasitic drugs for kinetoplastids is very sort of biased, based on that idea of, you know, what causes this disease which might, you know, be helpful in social contexts but that shouldn’t be the only way. But if you can tell us about, you know, what you see, you know, how this philosopher’s interest in definitions of these diseases and neglects, you know, these nations can influence other research areas.
Yes, and the thing that’s striking for me about the neglected disease stuff is that… I mean the way that it’s being pushed by people who are, you know, with their hearts very much in the right place, is that people have said, look, not enough research money is being spent on these diseases and that’s what neglect is, and, you know, we should fix it by spending more research money on these diseases and that seems to me to be not…
I mean that doesn’t seem to me to be quite right, because it assumes that the way you’re going to get rid of these diseases is by developing more drugs so my argument in the paper is that actually this… that standard strategy of saying okay, we’ve got to spend more research money on diseases; that’s not a way of working out how to cure or treat neglected diseases; it’s a way of working out how to do so and make a profit from doing so.
I think the… there are many other things you can do about diseases. There are public health initiatives. You can just arrange your society in a way that, you know, people receive better medical care. And the reason that I got on to this line of thinking about it is that it just struck me that many of the neglected diseases actually are preventable as they stand. I mean the striking thing is that when I worked through for a sort of good definition of neglect, what struck me is that none of the actual neglected diseases that are normally listed as neglected diseases, count as being neglected in that sense which is quite strange. They’re things, they’re all things that we could do something about if we just, you know, built some better roads or, you know, delivered refrigerated penicillin in the right places or whatever it might be so that’s… and that’s striking for me.
I mean I think if you look at the sort of interest of pharmaceuticals in this topic, I mean, you know, they sort of bash pharmaceuticals but, you know, ultimately they are not going to look for ways to help with neglected disease as simpliciter. They’re going to look for ways that will also make them money, and it may be great. It may be that in some cases that’s going to help, but for many things it’s just not clear to me that that’s… well, it’s not clear that follows, that’s automatically the case, and I guess, you know, I guess that was only part of the point that I was trying to make in, at least as regards to definition of neglect.
I would certainly agree with that. What I was wondering was whether you might have reached similar conclusions coming at a different academic perspective, so say policy where you might have thought about what the problem was and how the policy was framed or constructed or formed. Is that something you’ve come across during your work? I mean just tell us a bit about your thought process: how you collected evidence to make an argument in this case.
Well, it was… oddly enough I mean it was influenced… this line of thinking was influenced by my exposure to epidemiology because, of course, epidemiologists, you know, the primary… I mean epidemiology is the science of public health; it’s not really the science of medicine per se, so the primary sort of, you know, like, what an epidemiologist will think about is what public health interventions can we make. They won’t think what drugs can we made. So, I mean that… I mean, yes, it was the kind of… it was because of coming at the concept of neglected diseases from a sort of angle that was informed by public health, you know, policy that I came to that sort of idea.
I mean it’s tricky because I don’t know, I’m always very cautious of sort of veering out of, you know, areas of expertise and so forth. You know, you can be a good philosopher of science and be able to talk all about evidence and confirmation and just come up with the most ridiculous policy recommendations so you know, you obviously need both things. You obviously need to be empirically informed, but just from a…
I mean, you know, I think everyone, obviously understands that policy needs to be empirically informed but what’s interesting for me is that I think that policy also needs to be informed, you know, kind of conceptually and by a kind of clear understanding of what’s going on and, you know, the definitions that you start out with un these sorts of cases often really matter, so if you start off with a definition, neglected disease, it just automatically narrows all the tension onto how much money is being spent on the development of a drug, then that’s just going to have an effect, and I suppose that’s where ‘d see my sort of contribution in a policy context, is trying to sort of, trying to provide some sort of, well, maybe not a foundation but some kind of, at least some kind of clarity or some kind of analysis of the conceptual basis on which things are happening.
So, on that note it would be interesting to hear your opinion about how active you should be within the policy circles or you should just think about it, you know, as you do now, publishing papers and then these idea are getting picked up or you should be an active member within that policy circle.
It’s tricky. I mean I think that… I mean the thing about policy is that, you know, you do have to actually… you know, you do have to know what you’re talking about. You can’t just… you know, you can’t just sort of express opinions, and sometimes academics can… it can be hard because as an academic, you know, you’re sort of playing with ideas and you’ll, you know, that’s your job; you’re sort of moving them around and you’re seeing what might work and what doesn’t, and you can do that because you have a professional insulation from the consequence of these ideas. You’re not… you know, that’s the whole point of the academy. And it’s a different thing to engage in, you know, in what’s actually going on. That’s not… I do actually think that academics should engage in policy debates when they have things to offer. It’s just that you have to be, you have to know that you do have something to offer.
I mean from my part, I do have some sort of contact with these sorts of arenas, but I think it’s a matter of… I think it’s a matter of time and seniority as well. I mean, I wouldn’t be surprised if, you know, if in some years’ time I was involved in those sorts of contexts, but I mean it’s, you know, it’s tricky. I mean if you’re sort of involved in normative ethics, then you can see how you might end up sitting on a committee about neglected diseases, but if you’re a philosopher of science, people often don’t think to involve you, you know.
Oh, I can understand that, as a philosopher of science student at the moment. I guess we’ll go back to talking more of philosophy. Can you tell, actually we didn’t really much talk about this but can you talk about the contrasting model with regards to neglected diseases and how we can define neglected diseases on that, because our listeners will be interested in your definition of neglected disease?
Okay, well, look, I mean the point of the contrasted model is, as I said, you just… I mean, the idea is simply to… I mean define diseases in terms of some pattern of causes that all cases of disease share, and that pattern, at least part of it has to be absent from every case that doesn’t have the disease.
The slightly complicated thing about this is that there’s a kind of… there’s an element of stipulation. It’s very hard to sort of get your head around this, but it’s not the case, for example, that we discovered that cholera was caused by vibrio cholera. What we discovered is that among people with sort of violent diarrhoea, a certain bunch of them seemed to have this bacteria in their small intestines and we just decided that we were going to say that group of people, that disease is called cholera, and we’re going to define it by the presence of that bacteria in the small intestine.
So there’s no evidence you can bring to say that’s the right thing to do, and you can use the word cholera however you want to. It’s a matter of definition, so that’s the… I mean that’s the sort of… and I think getting your heard around that is the slightly complicated thing, so that way of thinking about disease, where you just have a signature cause is what I call the menocausal way of thinking about disease, and my idea was simply to try and just formalise this in a way that means you can have more than just one of them.
You can have a bunch of causes and what I say basically is that to have a disease you’ve got to have a sort of characteristic set of symptoms, and these symptoms have got to feature among their causes, certain characteristic set of causes and they… if not all the causes are present, but only some of them are, then you don’t have the disease even if you’ve got exactly the same symptoms as somebody else.
And that’s, the reason that’s hard to get your head around is the natural response is, well, you know, why do that, and the answer to that question is that there’s value in identifying general explanations for large categories of phenomena. So to me that would be a clearer… If you think of objects falling and you try and… you know, you can list all the different causes of objects falling, like boards being taken away and ropes being cut and so forth, but there’s one general principle that you can find, which explains all of them, and that’s the force of gravity acting on them.
And my criticism of the way that modern epidemiology has been tending to think about diseases is that because it, what it does, rather than try to identify signature patterns of causes, it identifies risk factors, which, if they’re present, you’re more likely to have the disease and if they’re absent, you’re less likely to have the disease but, you know, there’s just a huge sort of catalogue of these things.
And that, to me, is a bit like trying to identify risk factors for falling. I mean, you know, there are lots of things, you know, if you’re sort of on a thin board, that counts as a risk factor for falling, but I mean that, you know, cataloguing being on a thin board or being suspended by a, you know, a slender string or something, I mean cataloguing all these things is not going to give you a theory of gravity, and my thought is that if you have a definition of disease, which is a bit more rigorous, it will push you towards finding something that’s like a theory of gravity.
I mean, that is it’s a general explanation of large classes of phenomena, so in the cases of cholera, the point of excluding from the definition of cholera, people who have terrible diarrhoea, that don’t have vibrio cholera in their small intestine is that it yields this general explanation of a large class of cases, and that what makes it contrastive is this reference to explanation, so what you’re explaining is the contrast between people who have certain symptoms, say, violent diarrhoea or whatever it is, and people who don’t. And then the signature causes are present in those people with the symptoms, and absent in the other, in the control case. I hope that makes some sort of sense. I mean that’s just the definition of disease, the contrastive definition of disease component.
I guess the important point for neglect of tropical disease there is that we can identify many causes and then we can extrapolate from them, but we are not being vague about… you know, we are not confined with the risk factors or just one cause but we can actually talk about many causes and address those within the contrastive model, would that… would you say that’s a fair sort of summary of it?
Yes, I mean there are many, many causes of neglected diseases. I mean the point about the contrastive model is just to distinguish that claim from the claim that all of these causes are used for defining the disease. It may be that poor railroads are a good, you know, are part of the explanation for the prevalence of yours in a particular region but I wouldn’t say they’re part of the definition of yours. I mean it’s, you know, it’s an infection?.
So, that’s the… and I think, you know, the point is that once you’ve got that distinction in place you can say… I mean, oddly enough, you can… it’s precisely because some of these diseases are so straightforward, they’re so simple and, you know, often they’re just infectious diseases, you know, if you sort of plug in this multi-factorial framework then you sort of, it sort of suggests some huge scientific mystery to be unravelled and then we’ve all got to, you know, do research to unravel it and it, in fact the problem might not be that at all.
The problem might simply be that the government of that country is, you know, incapable and that, you know, corrupt and the infrastructure’s terrible. I mean it might… so, that’s the… I mean it’s the kind of slightly old-fashioned kind of idea but it’s, you know, this idea that, you know, you can sometimes usefully distinguish between scientific questions and social questions, and sometimes doing so is actually quite a useful thing for the, you know, for the people who actually suffer from these diseases.
Well, I guess the interesting point to highlight there is even when you re-look at the pharmaceutical research on neglected tropical diseases, that it is not purely on what’s the, you know, biological cause of the disease and how we can get rid of it, but a lot of it is governed by the social circumstance as well. You said, you know, the refrigeration, etc, so it is quite naïve to, you know, have that biological chauvinism and I quite like that your contrasting model also kind of hosts this social side of it in, you know, definitions.
Also, to put your model and definition into context, where would you say that you feel it fits within other philosophical thinking?
Other philosophical thinking on what, on disease?
On disease, yes, specifically.
Well, I’m not actually… I mean oddly enough there aren’t really other theories of disease out there that I’m aware of. The philosophers of medicine [unclear] about health quite a lot, but they started with the assumption that health is the absence of disease, and disease is just the absence of health, and so you just start by defining one and then you automatically got the definition of the other.
But I mean as far as I know, I’m the only philosopher who’s actually thought about disease specifically and said, you know, what is it for something to be a disease as opposed to just being, you know, a broken leg. I mean a broken leg is obviously a case of ill-health but it’s not a case of disease, so at least it’s not a case of disease in the sense in which, you know, you’d say that cholera is a different disease from whatever, influenza.
I mean, if disease is just the absence of health, then obviously there’s got to be more to disease. Sorry, if diseases are different from each other there’s got to be more to disease than the mere absence of health because, you know, it would just otherwise, you know, there wouldn’t be a distinction. You’d just have absences of health.
Yes, I think we thought you were the only philosopher looking at this but I just wanted to check.
I’m cautious of saying it because there might be somebody. But I really haven’t heard of anyone. There’ve been a lot of people who’ve thought about health, and to that extent they have theories of disease, but not… they don’t have theories of disease in that sense that I’m talking about, like what makes, you know, what is… what makes one disease different from another.
I’m sure there must be somebody who said something about this, but there aren’t any sort of canonical theories. In epidemiology and so forth, people have thought about it a bit more, so in the history of actual medicine itself, there are some people. I mean Robert Cog [?], back in the 19th Century, you know, had some pretty strong ideas about what a disease was, and there’s all this stuff I’m referring to, the sort of multi-factorialism and the… there this an implicit idea about what diseases are, but among philosophers and philosophers of science it’s not really… it you haven’t been a topic that I’m aware of.
That’s very interesting. And do you think you will continue using neglect tropical diseases or neglected tropical ill health in your, you know, future research? Or neglected diseases?
Yes, I think so. I think… I mean I think it’s an interesting field. It’s interesting because of the fact that philosophers and other academic… academics from other disciplines have tried to become involved, you know, try and actually make things happen. I mean people like Thomas Poggy [?] and so forth can actually you know, can actually do something about this and they really see an opportunity for that, so it makes it interesting from that point of view.
I don’t know how welcome my sort of perspective would be, I mean because the emerging sort of consensus seems to be that, you know, pharmaceuticals can sort of get together and be incentivised and persuaded and cajoled to sort of develop things that can be used for this but, I mean, I live in South Africa and one of the most famous health activists is a chap called Kinsley Holgate, who’s a big bearded chap with a Landover who did a huge amount to fight malaria by just driving around in his Landover in, you know, sub-Saharan Africa, distributing mosquito nets which obviously requires zero R&D funds, you know.
So, you see that sort of thing and you’re actually, you know, you see the sort of challenges that are faced. A lot of it seems to have absolutely nothing to do with the development of new drugs. A lot of it is to do with the social condition that… and political conditions concerning the distribution of things we already have. That’s not to say that there aren’t cases where new drugs would be useful. It’s just that I don’t… I’m quite sceptical of simply assuming that that’s where all the effort needs to be focussed.
Well, I think, which we’ll cover this topic in a future episode but there are, you know, certain effort in public/private partnerships who are, you know, trying to tackle this situation, not just from the pharmaceutical point of view, but they try to, you know, mobilise their resources in whichever case that they can, and this can be just be driving around in a Landover and giving out nets.
That’s very good.
So, I guess we are drawing to an end here. Thank you very much for joining us, Alex, and it’s pleasure to talk to you about it.