Intervista a Hasok Chang

Introduction

In December 2025, the University of Bologna had the pleasure of hosting the eminent historian and philosopher of science Hasok Chang, a board member of the Philosophy of Science Association and currently Hans Rausing Professor in the Department of History and Philosophy of Science at the University of Cambridge. During his stay in Bologna, Professor Chang participated in an interview organized by Professors Raffaella Campaner (Department of Philosophy) and Matteo Cerri (Department of Biomedical and Neuromotor Sciences). The interview has been transcribed and is now published on Segnalibri Filosofici.

The interview engaged with many of the scientific and philosophical themes explored by Hasok Chang throughout his career. Professor Chang’s philosophical view is expressed in his three major works on the history and philosophy of science: Inventing Temperature. Measurement and Scientific Progress, published by Oxford University Press in 2008; Is Water H₂O? Evidence, Realism and Pluralism, published by Springer Nature in 2012; and Realism for Realistic People. A New Pragmatist Philosophy of Science, published by Cambridge University Press in 2022. This introduction will outline the main topics covered by Hasok Chang during the interview and will guide the reader through his position in the field of philosophy of science. Chang’s pragmatist and pluralist realism will be reconstructed considering his main philosophical works, and the classic themes of philosophy of science with which Chang engages will be clarified.

To understand Chang’s contribution to the philosophy of science, it is first necessary to consider how he encountered philosophy. As he said in the interview, Professor Chang began his academic career as a student of physics at Caltech (California Institute of Technology). However, the young enthusiastic physics student soon realized that becoming a scientist demanded a certain rigidity. Physics students, like students in other scientific disciplines, are often trained to think and act in prescribed ways, adhering to consolidated paradigms. This model of scientific pedagogy closely aligns with the account of “normal science” developed by the philosopher of science Thomas Kuhn. As Kuhn stated in The Structure of Scientific Revolutions (1962), each historical period has its own scientific paradigm, that is, its set of theories accepted by the scientific community. During periods in which accepted theories are regarded as immutable, “normal science” occurs and future scientists, like young Hasok Chang, are trained to solve puzzle-like problems to find answers already predicted by the paradigm. When one of Chang’s professors told him, «I’m going to teach you to calculate. Don’t ask what anything means», he realized that the field of physics alone wouldn’t satisfy his desire for questions, and so he discovered the philosophy of science. Moving from physics to philosophy, Chang understood that philosophy constantly challenge what scientists are taught as self-evident truths. For example, in Is Water H₂O?, Chang shows that even an assumption commonly taken for granted, such as the chemical nature of water as H₂O, actually had to overcome the resistance of famous scientists, such as John Dalton, and was established only through a long and complex historical process.

Upon entering the philosophy of science, Professor Chang was also confronted with one of the most enduring and contentious debates in the field: the opposition between scientific realism and scientific antirealism. Realists think that scientific theories can be evaluated as true or false, and they think there are sufficient reasons to believe that some of the current scientific theories accurately capture the true structure of the world. Moreover, realists maintain that the unobservable entities (i.e., entities not directly accessible to human perception without the aid of instruments) posited by these scientific theories are genuine constituents of the world. One of the most demanding forms of realism is metaphysical realism. According to metaphysical realism, the theories accepted by the scientific community consist of propositions that literally correspond to the structure of the world. Antirealists, on the other hand, hold that scientific theories are human devices for interpreting the world and, precisely because they are interpretation, cannot aspire to capture the mind-independent structure of reality. From this perspective, unobservable entities are conceptual mind-products rather than real components of the world. One of the most demanding forms of antirealism is instrumentalism. According to instrumentalism, scientific theories are mere predictive instruments, valuable for their practical success but incapable of delivering true knowledge about the ontological structure of the world.

Chang endorses realism, as suggested by the title of his latest book, Realism for Realistic People. However, Chang’s version of realism departs significantly from standard scientific realism. He suggests that the most serious threat to realism is an excessively demanding version of it. Metaphysical realism sets the epistemic bar too high for science, thereby exposing it to antirealist criticism whenever a theory fails to grasp the ultimate structure of reality, which in scientific practice happens every time. Like antirealists, Chang acknowledges that human understanding of the world is necessarily framed by the mind. From this standpoint, the notion of a mind-independent noumenal reality is dispensable. Moreover, Chang is aware that a careful examination of the history of science undermines the idea that scientific enquiry can achieve a single definitive account of the world. The history of science contains numerous examples of highly predictive theories that, despite their success, turned out to be false. Based on these cases, it is possible to draw a pessimistic induction, suggesting, for example, that scientists of the future will view Einstein’s relativity as contemporary scientists view Aristotelian physics. Nevertheless, this critique of metaphysical realism does not commit Chang to antirealism. Like realists, he believes that not everything can go as a scientific theory. He also thinks that scientific theories and the entities they posit can meaningfully be regarded as true or false and considered genuine constituents of the world, provided that they satisfy certain conditions. Chang thus avoids both the threat of antirealism’s absolute relativism and the unrealistic commitments of metaphysical realism. The kind of realism he ultimately achieved is a form of pragmatist realism, as suggested by the subtitle of his latest book, A New Pragmatist Philosophy of Science. Chang is careful to stress that his pragmatism should not be conflated with the common stereotype that comes to mind when one hears the word “pragmatism”, namely, “whatever is convenient according to me is true”. Chang argues that this misunderstanding originates in an unfortunate choice of words by William James, founder of pragmatism together with Charles Sanders Peirce, in his definition of truth. Therefore, Chang also aims to rehabilitate William James’s definition of truth through his own new definition of truth by operational coherence. Operational coherence consists of activities in which everything «fits together nicely» (Chang 2022, p. 24). Coherence arises from the harmonious coexistence of various aspects of an activity in order to achieve specific aims, and it can be therefore understood as «aim-oriented coordination» (Chang 2022, p. 24). Thus, in Realism for Realistic People, Chang establishes the conditions for determining whether an entity is real and whether a theory is true. Entities are real insofar as they can be successfully employed within coherent activities that presuppose their existence; theories are true insofar as coherent activities can be carried out following them. An activity is coherent if it makes sense to carry it out in order to achieve a given goal, even if that activity may not be successfully performed every single time. Therefore, an entity is not real because it corresponds to a noumenal reality independent of our cognition, but because the mentally framed conception we have of it can be integrated into coherent activities. Similarly, a true theory is not a proposition that literally corresponds to the noumenal reality of the world, but rather one that facilitates the organization of a system of practice that makes sense to follow to achieve a specific aim. Through a system of practice, that is, «a network of activities that function coherently together» (Chang 2022, p. 16), it is possible to attain what Chang calls “active knowledge”. According to Chang, active knowledge is action-based knowledge or «knowledge-as-ability» (Chang 2022, p. 18), and it is the core of scientific knowledge. As Chang said in the interview, the truth humanity can aspire to achieve is within our practices, and knowledge derives from action.

In the interview, Chang also talked about the truth of theories by operational coherence through two examples. One concerns the concept of temperature and the other the concept of time. As Professor Chang wrote in his book Inventing Temperature, the scientific concept of temperature was first invented and only later validated through coherent practices. Prior to its quantification, humans could perceive heat through sensory experience, but temperature did not exist as a quantitative organized property in nature. Later, the introduction of thermometers demonstrated that the concept of temperature could be reliably employed in a wide range of coherent activities aimed at measuring and comparing thermal states. A second example is the concept of time, another human invention. As Henri Bergson observed, nature does not exist in a mathematical form, and mathematical time does not express what time really is. However, by introducing the concept of time, humanity has been able to engage incoherent practices such as the construction of clocks, which allow us to track temporal succession in a way that is cognitively manageable. In addition to being pragmatist, Chang’s realism is also pluralist. The truth of a theory can persist in certain delimitated domains even during major revolutionary phases in science. Newtonian mechanics, for instance, has historically supported a wide range of coherent activities within specific areas. Although the emergence of new theories, such as quantum mechanics, has generated new active knowledge, Newtonian mechanics continues to be true in all areas where it can support coherent activities. According to Chang, science should thus not be conceived as the progressive approximation to a single truth, but rather as the development of a plurality of truths. This pluralist perspective also explains why Chang, despite acknowledging the force of the pessimistic induction, does not conclude that most past scientific theories have been proven false. What the history of science reveals is the emergence of multiple theories proven valid in different domains of application, without thereby invalidating or falsifying their predecessors.

In the interview, Chang emphasized the difference between pluralism and relativism. Pluralism does not amount to a suspension of judgment in the face of multiple alternatives. The pluralist critically examines the plurality of positions in order to determine how many of them can be reasonably sustained. Once again, this goes against metaphysical realism. The claim that science progresses toward a single, final truth, ignores the concrete practices of scientific inquiry and exposes science to a twofold risk. On the one hand, it lends support to anti-scientific critiques that portray the absence of a stable, definitive truth as a fundamental weakness of science. On the other hand, it leaves as the sole possible defense of science a form of authoritarian dogmatism, in which one among the many truths is elevated to a tyrannical status. Chang’s aim is instead to introduce a form of healthy democratic pluralism into science. From politics, scientists and philosophers of science must learn to coexist with a plurality of positions, avoiding both anarchy and tyranny. As a pragmatist, Chang assigns a central role to action. Indeed, in the interview, Chang raised critical observations on the abuse of artificial intelligence in scientific practice. If AI were fully delegated the execution of scientific tasks, such as mathematical calculation, human practitioners might gradually lose the capacity to obtain active knowledge in those domains. To learn science, one must engage in scientific practice and the same holds for philosophy. For this reason, Chang would like to include philosophy in the education of science students to teach them to act philosophically, that is, to ask questions without restriction and to resist dogmatism. According to Chang, a productive relationship between philosophers of science and scientists is possible if philosophy doesn’t become too abstract. Scientists must be able to recognize their own practices in philosophical analyses, and this is precisely what philosophy of science in practice tries to achieve.

Finally, another aspect of Chang’s philosophy worth analyzing is his intent to provide a version of realism that «can be truly relevant to scientific work and useful in social and political life» (Chang 2022, p. 1). The connection between truth and operational coherence that Chang describes in science could indeed be extended to other areas of human life. For example, in politics, certain doctrines might be considered true or false based on their ability or inability to facilitate coherent activities. In Realism for Realistic People, Chang discusses the lack of truth-by-operational-coherence in Donald Trump’s words. Expanding on Chang’s example can be useful in providing concrete evidence of the interdisciplinary potential of his realism. According to the Trump administration, one of the key steps to “make America great again” is the large-scale deportation of undocumented immigrants from the United States. Adopting Chang’s realism, this political doctrine may be regarded as true only insofar as it facilitates coherent activities that make sense to be done in order to achieve Trump’s stated aim. In the last months, immigration enforcement policies have resulted in the forced removal of individuals who were well integrated into their local communities. Moreover, many ICE (United States Immigration and Customs Enforcement) operations have been accompanied by documented cases of excessive use of force, civilian deaths, and violations of civil rights. The activities supported by Trump’s political doctrine are operations that make no sense to pursue in order to achieve the greatness of a nation. Even if Trump’s definition of “national greatness” prioritizes the consolidation of the ruling class over the well-being of the population, the resulting policies still appear counterproductive. The escalation of coercive practices by law enforcement is fostering a qualitative leap in the consciousness of American working class, as demonstrated by the general strike held in Minneapolis on January 23, the first in the United States in 80 years. Such developments undermine the passive consent of the subordinate classes upon which ruling-class power largely depends. Consequently, when evaluated through Chang’s realist framework, it is evident that «it may be the case that Donald Trump often tells truth-by-honesty when he expresses his opinions (which is something that his supporters value), but the things he says really lack truth-by-operational-coherence» (Chang 2022, p. 179).

The interview

Segnalibri Filosofici – Welcome, Professor Hasok Chang, who is visiting us today at the University of Bologna. Professor Chang is a professor in history and philosophy of science at the University of Cambridge and one of the most prominent philosophers of science worldwide today. So thank you very much. We’re delighted to have you here and very much looking forward to having this conversation with you on hot topics in history, philosophy and science.

Hasok Chang – Thank you very much.

SF – Well, I’m going to ask you some questions, but first something to introduce you. You’re a philosopher of science, historian of science. What first drew you to this field? How did your passion start out?

HC – I was an undergraduate student of physics. I was very excited about physics as a teenager, went to a place called Caltech, California Institute of Technology, because I thought that’s the best place in the USA to do physics. And when I started into my actual physics education at the university level, I quickly realized that physics, maybe science in general, was not quite what I had imagined. So, a nice way to sum this up is the story of once when I got very excited about quantum mechanics and what it really means, and I tried to ask my physics professor about that. He said: «That’s a philosophical question», meaning don’t worry about it, you should just focus on doing your homework, solving the problems as we set them, not worry about what anything means.

SF – Do you have the feeling physics was more about making calculations and doing something practical somehow?

HC – That’s certainly the impression that I gained in trying to become a physicist, and in fact there was one professor later of quantum field theory who said, at his first lecture: «I’m going to teach you to calculate. Don’t ask what anything means». So, after such experiences, luckily I discovered that there was a field called the philosophy of science. I was even luckier in having some wonderful teachers. So back then, teaching at Caltech was a young, unknown philosopher of science called James Woodward. He was my first teacher in philosophy of science, and I realized this is what I need to do.

SF – I think philosophy of science has gained from you having done physics. So, maybe we can stay in the field of physics: did your concept of truth, or how we can understand truth, change in moving from physics to philosophy? And how do you see truth? Theories change and are constantly updated, so are we searching for something that doesn’t exist?

HC – Yeah, I had many changes in my own conception of truth as I went from being a science student to being a philosophy student, and to being an actual philosopher. But to address the last part of your question, yes, this is a huge question in philosophy of science, the pessimistic induction and all that. What I now believe is that there is a kind of truth which the pragmatists recognize, which is within our practices. This is a kind of truth that we can actually attain in actual practices, rather than this more common philosophical notion of the correspondence to a kind of inaccessible platonic reality. So I think there is truth in every successful domain of science, and generally speaking, that kind of truth remains, even when there are huge changes in theories. So why do we still teach every student of physics Newtonian mechanics, while we say “oh, it’s really false”? Well, it’s not false, it still remains true in all the areas in which it was true at the time of Newton and afterwards.

SF – But if I may, given the idea of truth that you are pursuing and you just so nicely explained, do you think it is still worth calling it truth, or might it be the origin of confusion, especially among lay people? So, shall we stick to the notion of truth, or maybe, I don’t know, call it differently?

HC – This is a question I often get, and for this kind of reason, in fact, if you look back at the pragmatist John Dewey, often just declined to talk about truth at all, while William James wanted to talk about truth. And my position is more aligned with James in that regard, because I think the kind of pragmatic truth that I just outlined is the same thing that ordinary people mean by truth when they say something is true in their actual lives, right? So, when we say: «Oh, it’s true that vaccines prevent COVID, or it’s true that people actually went to the moon», they’re not talking about the ultimate truth that philosophers like to talk about. So, I think, in fact, that correspondence notion of truth was a perversion of the idea of truth that had grown up in human life. So, I think we should stick to the idea of truth, but try to reclaim it for practical people, including scientists.

SF – I’m going to divert to an impromptu question, which we didn’t discuss. So, what do you think about the controversial fields of science, such as consciousness, at the moment? It feels like the only field of science where there are more theories than experiments. And the idea of what is truth or what is not, what is known and what is not, is constantly changing day by day. Just briefly, I don’t want to take you too far.

HC – I think there are areas of science in which not much has been established as truth, in which case we suspend our judgment and continue to search for something more stable.

SF – So, going back to your actual work: when Raffaella Campaner first recommended your book Inventing Temperature to me, I was immediately struck by the word “inventing.” By the way, I think it’s a great title: it really goes straight to the point. Could you explain what you mean by “inventing”? Is temperature something we create, or something we uncover through invention?

HC – Yeah, that’s a very good question. And I should tell you that, in fact, that was not the original title I proposed for the book. It was Oxford University Press which suggested it to me after the whole thing was accepted and I thought immediately, yes, that’s it. That expresses exactly what I was trying to say and I could put it in this way. When we successfully invent something, we actually discover something. Meaning, so what’s invented here is the concept of temperature, which didn’t exist always, at least as a quantitative thing. People didn’t really have this notion until people like Galileo and others invented thermometers and started putting numbers on sensations of hot and cold. So, the concept was invented, but the open question was: was it going to be coherent? So right now there are people trying to invent a quantitative concept of happiness, for example. They do questionnaires, but is it going to be a coherent quantity? I think we don’t know yet regarding things like happiness. The long history of temperature and thermometers and thermal science has demonstrated that it is a very coherent concept. So, we can now say there is something real and objective behind that concept. So, we invented the concept which turns out to be an element of reality, that’s how I would see it.

SF – So, to return to temperature and to my earlier point: we have an intrinsic sense of warmth and cold, and these sensations are processed by two different parts of the brain. More generally, do you think that phenomena rooted in our physiology have a better chance of giving rise to concepts that remain coherent over time, or is that merely coincidental? We do not directly experience, say, nuclear war, but we do experience gravity, temperature, and perhaps even electromagnetism when we move around in the world. Do you think this somehow provides an easier path toward stable knowledge? In other words, do we know what we are talking about because these things are directly felt and experienced by us?

HC – I think there is certainly an easier path to a scientific concept if we start from something we can experience. It’s not a certain path, because some things we experience are just not very grounded in external reality. But I think, especially if it’s something like the sense of warmth, which clearly has an evolutionary function in helping our survival, then I think we do have a good starting point, but science isn’t going to stop with those concepts. And you mentioned electromagnetism, and that’s a very interesting kind of case, because there’s a very, very limited base of sensation relating to electromagnetism. And we are in a place in Northern Italy where all that started with Galvani and Volta. So, there are some limited ways in which we can sense electromagnetism. But on the whole, the scientific concept had to be really worked up from some very abstract thinking.

SF – Yes, we can’t really percieve electromagnetism directly and say that this current is stronger than that one, it’s hard for our senses, unlike saying this weighs more, this is warmer, this is colder and so on, which comes easier. So, going back to a related topic: at this point, could we say that physical quantities are, after all, all invented? Like mass or time, for instance, or is temperature special in this regard, because of these physiological rules?

HC – No, I don’t think temperature is special. I think you could say that we’re not born with any quantitative concepts, perhaps other than very small numbers. So, whether we are talking about mass or the strength of electric field or temperature, it is a human creation to say that nature exists in this mathematical form. Something like time is very, very interesting. In fact, you can think back to someone like Henri Bergson who refused to acknowledge the currency of mathematical time. It simply didn’t express what time really is, what he called real duration, which isn’t mappable onto a number line, because as you go on and experience, there’s a qualitative change in what’s going on, so it’s not just a quantity that you can repeat.

SF – As a side question: you know the classic paper The Unreasonable Effectiveness of Mathematics in the Natural Sciences (Wigner 1959). What do you make of that idea? Why is mathematics so effective at describing reality?

HC – That’s a really intriguing question, and it’s somewhat like the question that scientific realists pose. Why is science so effective? Then their answer is, it must be because our theories are deeply true. Or they ask: why is science so good at producing successful theories? It must be because we have something correct figured out in scientific method. I think these are seductive questions and answers, but what we always have to remember is these questions are only meaningful when we have a contrast class. So, when we say mathematics is so effective, well... compared to what? What is it more effective than? And then I think the question is harder to answer, because, in fact, the mathematical way of doing things is the only way that we know how to do things in modern science. So, what would be the alternative?

SF – So it would still be mathematics, just a different kind of mathematics. It’s like asking whether an intelligent alien species would find that a different mathematics still works.

HC – So, one could ask, why are differential equations so effective in describing nature? And then there can be an alternative view saying: “No, no, actually, what’s even more effective is the discrete kind of mathematics that we use in computing”. And right now, I think there’s probably a fight between the two whose outcome is not very certain.

SF – And whether the reality is concrete or discrete.

HC – Yeah, who can say? So, I think we need to break down such questions into a more concrete form, and then we can try to answer.

SF – Moving on to something more concrete: just from the title of your second book – Is Water H2O?, which, by the way, I would recommend everyone read – one gets the impression that you are somehow challenging either chemistry or philosophy. Is that what you are doing?

HC – Yeah, that’s a very good question as well. The intention of that question is to make the listener realize they don’t actually know why they believe it. Because we all believe it. So the question is not really, is water H₂O? To which the answer from all of us would be yes. But the real question underlying it is: “How do we know?” And it turns out that most of us don’t know. We’ve simply been told in our school chemistry class, we start by being given the formula H₂O and also the formula H₂ for hydrogen, O₂ for oxygen, and what we learn to do is balance the equation between those things. So, what I do in that book is going into the history to learn how actual chemists in the 19th century learned that water was H₂O and there’s a long story, as you know, about that. And immediately we learn that, for example, John Dalton, who really began the tradition of atomic molecular chemistry, believed that water was HO, one atom of each. And there’s a whole story about how, well, he never changed his mind about that, but a story about how other chemists came away from it and it begins again in Italy with Amedeo Avogadro, who first proposed the H₂O formula and initially nobody believed him. So, there’s an intricate story about this.

SF – I was thinking about what you were saying earlier: it’s true, we are taught the formula, we accept it, but we often do not really know why. So what does this tell us about meaning in science? Do you think we are living through a phase of scientific development in which technology is beginning to overtake meaning, where we are producing more and more experiments without necessarily extracting new concepts from them? I remember an editorial – I can’t recall whether it was in Science or Nature – discussing the growing number of papers in comparison with the declining number of real breakthroughs. The number of publications keeps increasing, while breakthroughs seem to decrease. So this raises some important questions.

HC – I do think we publish too much nowadays, even in philosophy. There’s hardly any time to read because we are all so busy writing. Setting that aside, I think there is a sense in which people may simply be learning to calculate without taking the time to reflect on what anything actually means. But the question of what meaning and understanding really are is itself a difficult one, right? It may even be an illusion to think that we can attain some higher level of understanding. What I am more certain about, however, is that we cannot achieve any genuine understanding if we do not do things ourselves. What I find truly harmful is this kind of “black boxing”: when we do not even know the algorithm that produces the answer, when we simply hand the question over to a machine or a formula, receive an answer, and accept it uncritically.

SF – You seem to be very aptly describing an AI system.

HC – Maybe so. But in terms of how people learn science, I think we need to learn how something is done, whether it be in the lab trying to make water or even in terms of computations, right? I think the reason why we should still teach people calculus, for example, is so that they have a sense of what it’s like for the Isaac Newton’s of the world to produce these results. How is it that we think about these continuous changes in physical magnitudes? What are the tools that we need in mathematics in order to be able to think about that? So the experience of doing something, even if it is the experience of calculating, right? To do that ourselves and to have a sense of what it means to acquire knowledge, I think that’s the important thing that we are now on the verge of destroying.

SF – It’s a meta-knowledge somehow.

HC – In some ways, right. So, you know, people in science education talk about teaching “NOS” in English, the nature of science, but unfortunately that often comes out as giving students a list of what science is like and they memorize this. No, I think the only real way to teach the nature of science is to allow students to experience knowledge-making.

SF – So, if you were to briefly design a science curriculum or a scientific curriculum, what role would philosophy have in your ideal class or teaching or curriculum?

HC – Yeah, the role of philosophy, I think, is very important but difficult to make explicit. So, I think the most important thing about philosophy is not to teach which great philosophers have what kind of doctrine, but to give the students a real sense of thinking. And by thinking, I mean being able to pose questions without a predetermined restriction, right? So that we can have the experience or give students the experience of truly challenging something that they are given. Because I think a real challenge to accepted dogma begins by asking a new question, not simply by giving an answer that the authorities may not like. It’s the question.

SF – Thank you so much. So just a couple of further questions in the very same direction. So, we’ve been talking about truth and the way in which you conceive it. And we know that you pursue a pluralistic perspective, a realist one, but also a pragmatist one. Your last words were concerning the role philosophy of science can have in educational settings. But what about the views of science in a more widespread sense? So how can philosophy of science contribute to the socially wide understanding of science? More specifically, you distinguish very clearly between pluralism and relativism. How can we defend a convincing form of pluralism without running the risk of slipping into an “anything goes” attitude — something that can be quite dangerous for trust in science, especially in the current context?

HC – And this is, of course, a huge question on everyone’s mind, and it would take a very long time to fully answer it. But let me pick up a couple of points. So, I think the distinction you refer to between pluralism and relativism is very important and often mistaken. The pluralist is not someone who says “whatever”. A pluralist is someone who says, “Let’s see what the plausible alternatives are, and let’s keep a reasonable number of them in play.” Because the pluralist also has to be realistic and recognize that not everything can be supported. In that respect, I actually think science still has a lot to learn from politics. People in science and philosophy often look down on politics as this immature, messy domain of human activity, but I think it may actually be the other way around. In many parts of the world, politics has figured out how to make something like multi-party democracy work, right? We’ve gone beyond the point where people are saying there’ll be complete chaos and disorder if we don’t have the king. Complete anarchy if we don’t have this totalitarian government. No, we’ve moved beyond that. And we said, no, trust can be maintained even if somebody doesn’t have ultimate authority. So, what is to trust in? Well, that’s the long story in which we educate ourselves to trust in some basic institutions of society, right? So, we all trust elections rather than trusting one particular party. And that way we can have multiple parties competing fairly. They’re the basic rules which we subscribe to, right? And if we think again about science, I think a lot of people who practice or defend science have a kind of autocratic impulse: “No, no, no – science is the truth, and everyone just has to accept it.” But I actually think that’s the immature attitude. In many ways, scientific institutions are not so far from being able to support something like the equivalent of a multi-party democracy, right? We have ways of reasonably debating difficult questions in science. But what’s not keeping up with that development is a higher level intuition about what truth is, right? Because we’re still tied to this notion there is one truth and everything needs to conform to that. So, this I think is where philosophy of science can help by introducing a more relaxed notion of truth that ordinary people as well as practicing scientists can all recognize.

SF – Thank you. You’ve also advocated a sort of activist realism. You very much believe in this commitment and have also contributed in recent years in a very significant and effective way to what we now know as the philosophy of scientific practice. So, I would like to hear your views on how broad you think scientists’ interest in philosophy and in philosophy of science particularly is today. But also what are the distinctly, peculiarly philosophical features ofa philosophical discourse on science? Do you see any difference between a theoretical discourse on science and philosophical discourses on what science is about and what its goals are? Is there any difference or maybe not?

HC – Yeah, that’s a difficult question. To go back to what you were saying at the start, I think a lot of scientists are philosophical at least in some moments. They don’t tend to call it philosophy, but they do this debate, these questions with each other. So, when it comes to questions like reductionism, scientists have a lot to say about this and they have different opinions and they argue with each other. What scientists don’t tend to relate very well to is when we philosophers go very, very abstract. When we talk in a way that scientists cannot see their practices in what we’re saying, that I think is where we have the unproductive disconnection, and that’s the kind of problem that people who advocate the so-called philosophy of science in practice have been trying to overcome. But I think what’s really distinctive about philosophy, in my mind, goes back to what I was saying a little bit earlier. I think ultimately philosophy has to be the field in which we can ask questions without restrictions, and I mean, much of analytic philosophy is not like that. Much of analytic philosophy is very much like what Kuhn called normal science. We have very specific ways of addressing questions and very strict judgements about what is a good answer right now. But in the end, I think what deserves the name of philosophy has to be free to question any of the assumptions that we bring into the debate. And that, I think, that is something that’s not easy to accommodate within science. Within science, I think even when scientists are being very philosophical, they’re still asking questions about the specific scientific tasks that they’re dealing with. So, I think that’s the role of philosophy in the end.

SF – Now, the very last question, and we really thank you for your kindness and availability today. What do you think are the major challenges in science these days that are most stimulating, driving, or orienting philosophy of science? What are we going to study more deeply in philosophy as a result of what science is teaching us, or the directions science is currently taking?

HC – That’s a huge question. I mean, I think one area certainly is the whole quandary about artificial intelligence.