Tag Archives: consilience

Scientism: Part 4: Reductionism

This is the Fourth Part of a review of Science Unlimited? The Challenges of Scientism, edited by Maarten Boudry and Massimo Pigliucci. See also Part 1: Pseudoscience, Part 2: The Humanities, and Part 3: Philosophy.

Reductionism is a big, bad, bogey word, usually uttered by those accusing others of holding naive and simplistic notions. The dominant opinion among philosophers is that reductionism does not work, whereas scientists use reductionist methods all the time and see nothing wrong with doing so.

That paradox is resolved by realising that “reductionism” means very different things to different people. To scientists it is an ontological thesis. It says that if one exactly replicates all the low-level ontology of a complex system, then all of the high-level behaviour would be entailed. Thus there cannot be a difference in high-level behaviour without there being a low-level difference (if someone is thinking “I fancy coffee” instead of “I fancy tea”, then there must be a difference in patterns of electrical signals swirling around their neurons).

To philosophers, however, “reductionism” is about explanations and theories. It asserts something along the lines that high-level explanations can always be translated into low-level explanations, and that the low-level explanations are more important or more proper, and that ideally the high-level explanations could be dispensed with. I say “something along the lines” because this sort of eliminative reductionism is pretty much a strawman in that no-one (sensible) advocates it. And philosophers are right, in general it does not work.

But the scientific notion of ontological reductionism does work. At least, all of science assumes that thesis, and science works very well, producing unarguable and unmatched mastery of technology and engineering. Since adopting that thesis works so well we can be pretty sure that ontological reductionism (which philosophers may instead refer to as “supervenience physicalism”) is a true feature of the real world.

But the different meanings lead to miscommunication. “Scientism” is supposed to include a naive faith in reductionism, which the accuser would take to be the philosophers’ inter-theoretic reductionism. But those defending scientism are likely to think like scientists, and so hold only to ontological reductionism but not defend ideas of inter-theoretic reductionism. The latter might work in limited instances, but does not work in general.

Most physicists would agree. In his Reductionism Redux essay, Stephen Weinberg refers to inter-theoretic reductionism as “petty” reductionism, saying that it usually doesn’t work, while he regards ontological reductionism as a “grand” reductionism that underpins all of science. Similarly Sean Carroll defines reductionism as the idea that “objects are completely defined by the states of their components”, and says: “I could imagine hypothetical worlds in which reductionism failed … It’s just not our world”.

Carroll also says that one can “object to the claim that ‘the best way to understand complex systems is to analyze their component parts, ignoring higher-level structures’, but only if you can find someone who actually makes that claim”, and adds that: “nobody thinks that the right approach is to break a giraffe down to quarks and leptons and start cranking out the Feynman diagrams”.

So let’s see what the philosophers in Boudry and Pigliucci’s book make of the concept. Filip Buekens accepts Alex Rosenberg’s claim that “physics fixes all the facts” (by which Rosenberg means the supervenience thesis that the state of a complex system is completely specified if all its low-level physical properties are specified), but he demurs about the “much stronger claim” that “all other facts are ultimately explained by physics”.

He continues: “conceptual anti-reductionism holds that explanations employing psychological concepts cannot be replaced by explanatory strategies relying on physical concepts”. So one could not translate the concept “fear” into language about electrons and protons and their motions.

He’s right on the latter point, but it’s important to realise that explanations are not mutually exclusive. Explanations are always commentaries about some aspect of a system. They never describe the entirety of a system. And that means that multiple different explanations can be true at the same time.

The doctrine of supervenience says that one could — given an advanced Star Trek transporter device — exactly replicate a system from an exhaustive listing of every particle it contains (and the replicated system would manifest the same high-level properties including “fear”). But an “explanation”, being a commentary about aspects of a system, never contains enough information to do this. You could not feed “Tom was afraid of the dog” into the transporter and exactly replicate Tom and the dog from that alone.

The same holds for explanations used in physics. They also are reduced-information commentaries; physicists no more work with exhaustive listings of particles than psychologists do — they are too unwieldly and so impractical as to be useless. Thus, even in physics there are multiple higher-level concepts (such as “temperature”, “entropy”, “elasticity”, “ductility”, “conductivity”) that are properties of an ensemble, and which are not even defined at the lower level of single particles.

Since, for any system, there will always be many mutually-consistent and equally-true explanations, it follows that even if one develops explanations of high-level properties in terms of lower-level properties, these will never replace and do-away with high-level explanations, they will only add to and complement them.

Richard Feynman said that any good theoretical physicist knows six different ways of thinking about the same thing. Explanations at different levels of description are complementary ways of thinking about the same thing. They don’t replace or abolish other explanations, instead they must all be simultaneously true. And the different explanations are held together, coherently, not by the philosophers’ notion of inter-theoretical reductionism — not by translations between different explanations — but by the doctrine of ontological reductionism or supervenience.

As an aside here, philosophers use the weird term “special science” for sciences where inter-theoretic reductionism is held not to work, and by doing that they imply that it does work for at least some sciences, by which they usually mean physics or perhaps fundamental physics; they are wrong, it does not work even there, there are no “special” sciences since they are all “special”.

I can’t help thinking that much philosophical travail against inter-theoretic reductionism is misplaced, in the sense of attacking doctrines that no-one holds. Stephen Pinker’s essay on the humanities aroused fears of a hostile take over that reduces the humanities to a mere adjunct of science. But, as Russell Blackford explains in his contribution to the volume, that is a mis-reading of Pinker, who is instead arguing for a consilience in which different styles of approach complement each other.

Similarly, Taner Edis expounds a scientism that “highlights continuities in the various ways we produce knowledge, and weaves the products of our knowledge-seeking enterprises into a naturalistic overall picture”, saying that: “this scientism is harmless: it seeks connections and coherence, not intellectual conquest”.

The most direct condemnation of reductionism in the book is by Mariam Thalos. Declaring reductionism “the enemy”, she argues against sociobiology and the claim that, because human brains have evolved “therefore biology explains human behaviour too, utilizing principles of natural selection”. But that’s true, it does!

Thalos, however, suggests that accepting this idea “would with one stroke sweep away all competing models of human behaviour”. Interpreting that narrowly, yes it would sweep away competing models — those that are incompatible with the sociobiology perspective. But it would not sweep away complementary models and explanations — those that are different from but compatible with the evolutionary perspective, and which are equally true.

Thalos generalises her argument: physics explains the behaviour of physical bodies, humans are made of physical stuff, therefore physics explains human behaviour. “Whence, biology, as such, is made irrelevant.”

To this she adds that if we accept that “physics explains human behaviour, utilizing physical principles”, then “we are explicitly denying the need for biological theory as independently valuable in the enterprise of scientific explanation”. Thus, to Thalos, only one type of explanation can be valid. Physical systems can only be explained in physical terms; biological systems can only be explained in biological terms.

No! This is a rejection of the “grand reductionism” that is the very soul of science. Complex systems (such as humans) need explanations at all levels of analysis. We should develop explanations of humans in physical terms, and in chemical terms, and in bio-chemical terms, and in biological terms, and in evolutionary terms, and in psychological terms, and in sociological terms, and in the languages of the humanities. All such explanations complement each other and mesh into a grand, consilient picture. The different explanations don’t compete with or displace each other, they complement each other. They must all be mutually compatible and mutually build to an overall grand picture in which they are all true.

That follows from the doctrine of scientific or ontological reductionism, which holds everything together because it tells us that all these different explanations are about the same ontological stuff; they are reporting different aspects of the same ensemble. And that is the consilient grand picture of science and of scientism.

This is not a merely philosophical point, it is eminently practical. Given multiple explanations about the same stuff, we then need to ensure that they are fully compatibile, and investigating that is the central driving force of science. Ensuring that the explanations in physical terms mesh seamlessly with the explanations in chemical terms, and with the bio-chemical explanations, the biological explanations, and the evolutionary and psychological explanations, is exactly how science makes progress.

Any field that wants to stand aside from that process risks turning itself into a parochial fiefdom prey to fads and ideologies (a current example being areas of sociology that totally ignore the genetic underpinnings of human behaviour), and deprives itself of the best tool that science has.

Science Unlimited, Part Two: The Humanities

This is the Second Part of a review of “Science Unlimited? The Challenges of Scientism”, edited by Maarten Boudry and Massimo Pigliucci. Part 1, focusing on pseudoscience, is here.

The Claim of Scientism can be stated overly crudely as “science is the only way of answering questions”, which of course is guaranteed to raise hackles. But in the non-strawman version scientism does not assert that humanities can never contribute to knowledge, instead it asserts that ways of finding things out are fundamentally the same in all disciplines. Any differences in methods are then merely consequences of the types of evidence that are available, rather than reflecting an actual epistemological division into “different ways of knowing”. The prospect is not, therefore, of a hostile takeover of the humanities, but of a union or conscilience (to use a term that E. O. Wilson revived from Whewell).

In its least offensive statement, scientism states that science is pragmatic, and that it will use any type of evidence that it can get its hands on. Continue reading

Basics of scientism: the web of knowledge

scientism A common criticism of science is that it must make foundational assumptions that have to be taken on faith. It is, the critic asserts, just one world view among other, equally “valid”, world views that are based on different starting assumptions. Thus, the critic declares, science adopts naturalism as an axiom of faith, whereas a religious view is more complete in that it also allows for supernaturalism.

This argument assumes a linear view of knowledge, in which one starts with basic assumptions and builds on them using reason and evidence. The fundamentals of logic, for example, are part of the basic assumptions, and these cannot be further justified, but are simply the starting points of the system.

Under scientism this view is wrong. Instead, all knowledge should be regarded as a web of inter-related ideas, that are adopted in order that the overall web best models the world that we experience through sense data.

Any part of this web of ideas can be examined and replaced, if replacing it improves the overall match to reality. Even basic axioms of maths and logic can be evaluated, and thus they are ultimately accepted for empirical reasons, namely that they model the real world.

This view of knowledge was promoted by the Vienna Circle philosophers such as Otto Neurath, who gave the metaphor of knowledge being a raft floating at sea, where any part of it may be replaced. As worded by Quine: Continue reading

The unity of maths and physics revisited

scientism A major part of scientism is the idea that maths and logic are not distinct from science, but rather that they arise from the same fundamental root — they are all attempts to find descriptions of the world around us. The axioms of maths and logic are thus equivalent to the laws of physics, being statements of deep regularities of how the world behaves that enable us to describe and model the world.

My article advocating that mathematics is a part of science was recently posted on Scientia Salon. This was followed by an article by Massimo Pigliucci which took the opposite line and criticised the return of “radical empiricism”.

In response I wrote about the roots of empiricism, defending the radical empiricism that Pigliucci rejects. That post was getting rather long, so I have hived off parts into this post where I return to the distinction between mathematics and science. This is essentially a third part to my above two posts, countering various criticisms made on Scientia Salon.

To summarise the above arguments in two sentences, my critics were saying: “Well no, mathematics is anything but studying physical objects. It is the study of abstract concepts”, whereas I was saying, “Yes, mathematics is the study of abstract concepts, abstract concepts that are about the behaviour of the physical world”.

I have argued that maths and logic and science are all part of the same ensemble, being ideas adopted to model the world. We do that modelling by looking for regularities in the way the world works, and we abstract those into concepts that we call “laws of physics” or “axioms of maths” or of logic. Thus axioms of maths and logic are just as much empirical statements about the behaviour of the world as laws of physics. In part one I discussed other possible origins of mathematical axioms, while in part two I discussed the fundamental basis of empirical enquiry.

That leaves several possible differences between maths and science, which I address here: Continue reading

On Wieseltier on Pinker: How to misunderstand scientism in one easy step

One theme runs through most discussions of scientism: two sides are talking past each other because they have very different conceptions of science and interpret the word very differently. Never has this been so exemplified as by Leon Wieseltier’s response to Steven Pinker’s widely discussed piece “Science is not your enemy”.

Those defending scientism conceive of science broadly. They see the universe as a unified whole and take an overview of our attempts to gain knowledge of this whole. They see a separation into different disciplines as a useful labelling, but not as reflecting any underlying rifts or divisions in how the world actually is, or in our knowledge about it. Between any arbitrarily defined academic disciplines there always lies a seamless transition of inter-disciplinary learning.

The essential commitment of scientism is the attitude that the same underlying rules of evidence and logic and reason apply everywhere, across all academic disciplines. Thus the different disciplines differ not in fundamentals, but in the subject matter and in the practicalities of investigating different topics.

Further, a scientist sees humans as very much a product of the natural world, as one species that has evolved among millions of others over eons of time, and very much bearing the stamp of our origins. To those espousing scientism, learning about social interactions among humans is just as much a science as learning about social interactions among chimpanzees or zebra. Studying humans as they are now or as they were one thousand years ago transitions seamlessly into studying humans as they were a hundred thousand years ago, or how their ancestors were ten million years ago.

All biological processes are continua, and to set a rigid date and declare that investigation of humans as they were earlier than (say) 6000 years ago is “science” but that investigations of humans more recently is not a science, but instead an arts/humanities subject, is utterly arbitrary and alien to how scientists think.

Further, to pick one species out of the 30 million extant species and to declare that studying that one is not a science, whereas studying any of the other 30 million would be, is contrary to our whole scientific understanding of humans as a natural part of the natural world.

Thus, to a scientist, it is natural to think of the study of humans (history, economics, politics, and the study of the literature and art that humans create) as a branch of anthropology, the study of ourselves. This isn’t just semantics, it’s the way that evidence has led scientists to think about humans. Continue reading

What does “science” in “scientism” mean?

Scientism is usually an accusation, an insult hurled at someone who is accused of not knowing the limits of science, and of arrogantly and ignorantly stomping all over areas of human interest that are the proper domain of “other ways of knowing”. Yet, increasingly, the word “scientism” is being claimed by defenders and supporters of a scientistic outlook. This can lead to differing definitions of “scientism”.

I personally define “scientism” to mean the claim that any questions to which humans can know the answer (with some confidence in the reliability of their knowledge) are answerable by science, and that science is the right tool to gain that answer. Or, stating the same another way, any method of finding such answers becomes part of science. A third way of saying this is the assertion that there are no “other ways of knowing” that are fundamentally distinct from science and that can do better than science.

Thus science is largely defined by “what works”, being the set of methods that have been established to give reliably true answers, methods that have been selected and honed precisely as a result of finding out what does work.

The underlying idea is that the natural world is a seamless whole, with no clear and uncrossable divides between different domains. Hence, knowledge about the world is also a seamless whole, and principles of evidence and reason apply the same everywhere. Thus evidence- and reason-based enquiry is the proper tool for investigating any area of human interest.

This is an explicit rejection of the “non-overlapping magisteria” idea that different areas of human enquiry are divided into rigidly demarked zones where different rules apply. No-one has established that different rules do apply, and the claim is usually made as a way of avoiding tiresome requests for evidence. Science keep out! We don’t want to have to supply evidence, we want to believe whatever we want to believe without having to justify it in any objective fashion!

This raises the question of what we mean by “science”. Continue reading