Category Archives: Philosophy

Are predictions an essential part of science?

Theoretical physicist Sabine Hossenfelder recently wrote that that “predictions are over-rated” and that one should instead judge the merits of scientific models “by how much data they have been able to describe well, and how many assumptions were needed for this”, finishing with the suggestion that “the world would be a better place if scientists talked less about predictions and more about explanatory power”.

Others disagreed, including philosopher-of-science Massimo Pigliucci who insists that “it’s the combination of explanatory power and the power of making novel, ideally unexpected, and empirically verifiable predictions” that decides whether a scientific theory is a good one. Neither predictions nor explanatory powers, he adds, are sufficient alone, and “both are necessary” for a good scientific theory.

Popper’s criterion of falsification (the possibility that a theory’s predictions can be empirically refuted) is, of course, one of few elements of the philosophy of science to have attained widespread awareness. But is Popper’s maxim descriptive or prescriptive? If it merely describes what scientists tend to do, then, if scientists came to feel that predictions were not so crucial, would their enterprise still be “science”? Or, if the maxim is prescriptive, such that falsification is a necessary part of the scientific method, then by what authority is that prescription established?

To answer that, let’s turn to Feynman’s well known summation of science:

The first principle is that you must not fool yourself — and you are the easiest person to fool.

Scientists do their best to construct the best and truest model of the world. Pseudoscientists have fooled themselves into a false understanding of the world. And it’s easy to do that, because, given a set of facts, anyone can construct a story that weaves those facts into an overall picture that the story-teller wants to be true. They may need any number of ad hoc explanations, but humans are good at that. It’s easy to sustain the belief that, say, God always answers prayer, if you allow yourself wide flexibility about what the answer looks like, including “God said no this time”.

So both Hossenfelder and Pigliucci are right: a good scientific theory needs to explain the maximum amount of data with the minimum number of ad hoc features. But predictions really are the acid test. If you are making predictions about things where you don’t already know the answer, then your ad hoc explanations will prove useless and sterile. Only an accurate theory — one that correctly describes aspects of the world — will be able to reliably generate predictions that turn out true. This is why making predictions about things you don’t know, and then attempting to verify them, is the gold-standard method that all scientists should adopt when they can, to check whether they have fooled themselves. The telling give-away of the pseudoscientist is their reluctance to submit to that test.

But making predictions that can then be verified may not always be possible. Yes, the scientific method asks that such be done where it can be, but what if we’re talking about topics where the time required or the energy required are not possible? Need we conclude that such topics are beyond the domain of science?

Let’s take a concrete example. Given the finite age of the universe and the finite speed of light (and hence the finite speed at which information can travel from one region of space to another), we can never obtain information about the universe beyond an “observable horizon”, and thus can never empirically verify statements about such a region. Does that mean that any statement about such regions is outside science (perhaps being metaphysical or pseudoscientific)?

A further example concerns attempts to describe the physics of the Planck scale, which is relevant to attempts to find a unified description of the forces of nature, or to understand the origins of the Big Bang, yet which is orders of magnitude beyond our ability to recreate in particle accelerators. Is any such quest pseudoscience? And if it is, how far beyond our current ability to test is it permissible for scientists to construct theories? It would be weird to suggest that a factor 2 is acceptable, but a factor 10 not.

I prefer to fall back on Feynman’s dictum. If we’re discussing topics beyond our ability to test predictions then we need to be extra careful not to fool ourselves, since we won’t have the gold-standard test. But then in science we have to make do with the tools we have; neither cosmologists nor paleontologists can replicate findings in laboratory experiments, yet those fields are still sciences, despite what school textbooks might say about “the scientific method” and the requirement to replicate experiments.

We should see verifying predictions as similar to replicating experiments under laboratory conditions — yes scientists should do it where they can, as being the best ways of minimising self-fooling, but in the end science is pragmatic and often has to make do. Thus there is nothing unscientific about trying to understand aspects of the universe that we cannot directly test, one just has to be extra cautious in the claims one makes. A statement such as: “As far as we know, the universe continues much the same beyond the observable horizon” would seem to be a reasonable feature of a cosmological model, even though it is beyond empirical testing.

So, overall, predictions are not over-rated, but nor are they fully essential. I think this lands me roughly midway between Hossenfelder and Pigliucci.

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 Three: Philosophy

This is the Third Part of a review of Science Unlimited? The Challenges of Scientism, edited by Maarten Boudry and Massimo Pigliucci. See also Part 1, focusing on pseudoscience, and Part 2, focusing on the humanities.

Science started out as “natural philosophy” until Whewell coined the newer name “science”. As a scientist I have a PhD and am thus a “Doctor of Philosophy”. And yet many philosophers assert that today “philosophy” is an enterprise that is distinct from “science”.

The argument runs that philosophy is about exploration of concepts, and what can be deduced purely by thinking about concepts, whereas science is heavily empirical, rooted in observation of the world. Thus philosophy (exploration of concepts) and science (empirical observation) are fundamentally different beasts. And both are necessary for a proper understanding.

But, for this distinction to hold, a necessary corrollary is that science does not involve exploration of concepts, and concerns itself only with the accumulation of observation. Yet to me that is an utterly impoverished view of science, and one that is untenable. In order to advance understanding we need both the exploration of concepts and the guidance of empirical observation — either on its own won’t get far. Accumulating observations by itself is mere “stamp collecting” (to quote a derogatory remark that physicists aim at anyone not paying sufficient attention to explanations and understanding). As philosophers themselves know, all observation is “theory laden” in that one cannot even assimilate observational evidence without equal attention to what it means.

In essence, science is a continual process of revising and improving a “web of ideas” that contains our understanding of the world. We continually test the web by comparing its outputs to empirical data, looking for any mismatch, and then trying to figure out the best way of adjusting the web in order to eliminate the anomaly. It follows that attention to the internal coherence of the web of ideas, and exploring the implications of the ideas — and thus analysis of concepts — is a vital and basic part of the overall scientific enterprise.

The two halves of the whole are perhaps most clearly seen in physics, where practitioners are divided into “theoretical physicists”, who spend their lives exploring the implications of ideas and trying to scheme up better ones, and “observers” and “experimentalists” who concentrate on adding to the pile of empirical data that tests the concepts. Obviously this only works if the two halves are continually talking to each other, and so everyone sees themselves as part of the same overall enterprise, specialising in one “style” of science because division of labour allows the focused expertise necessary to make progress.

To me as a physicist, it makes little sense to read that some philosophers think that exploring ideas and concepts for their own sake is a philosophical activity that is “not science” and is clearly distinct from science. So why is it then defended by some philosophers? I suggest that the reason is sociological. Science nowadays is such a juggernaut that adjacent disciplines fear being trampled underfoot, and so jostle to establish a bailiwick of their own from which science is excluded. While understandable, such a path could lead to irrelevance.

Philosophy, with its role of asking certain types of question, is better thought of, not as distinct from science, but as a style of doing science, in the broadest sense of “science” as increasing our understanding of the world. Other “styles” of science, in addition to theoretical analysis, include accumulating observations, designing and performing experiments, and modelling a situation on a computer. The best approach is to combine and synthesize all of these styles. None of them would get us far on its own, and they best succeed in harmony with the others. Philosophy, therefore, is best done in close conjunction with adjacent disciplines, such as the sciences, and could condemn itself to pointless meanderings if it forgets that.

As expected, the authors in Science Unlimited have a spread of views on this issue. Maarten Boudry is closest to my own view, arguing against those of his colleagues who “still regard philosophy as independent from and conceptually prior to science”, and saying instead that: “much of philosophy is now tightly ensnared in the web of knowledge. Philosophy of mind shades into cognitive science, neurology, and linguistics. Epistemology is intertwined with cognitive psychology and evolutionary biology”, while declaring — correctly — that the sciences “often deal with conceptual issues that can be characterized as broadly `philosophical’ in nature”.

Stephen Law, however, is less sympathetic to this view, saying: “philosophical questions are, for the most part, conceptual rather than scientific or empirical”, and that: “in order to solve many classic philosophical problems, we’ll need to retire to the armchair, not to the lab”.

But, equally, theoretical physicists don’t work with laboratory equipment, taking measurements, they work with ideas and concepts. The internal coherence of concepts about the world is just as much a concern for scientists as for philosophers.

A current example is the black-hole information paradox, where the paradox is that current models of black holes suggest that “information” (which itself is a highly abstract concept, not a direct observable) is destroyed when material falls into a black hole. And yet, a basic principle of quantum mechanics (the best theory of matter, thought to apply everywhere) says that information can never be destroyed. Trying to resolve the inconsistency is currently exercising many of the world’s top theoretical physicists, partly because the solution might point the way to a model of “quantum gravity”, the long-sought unification of quantum mechanics with general relativity. Yet this activity is entirely conceptual, since observations and experiments pertaining directly to the issue are way beyond current capabilities. Physicists still regard the enquiry as “scientific”, even if some philosophers might want to declare it to be “metaphysics”.

Stephen Law’s own example is Galileo’s thought experiment of dropping balls from the top of the Leaning Tower of Pisa. The thought experiment demonstrates that balls of different weights must fall at the same speed, else one arrives at a contradiction. Law asks: “Is Galileo’s thought experiment an example of science, or of philosophy?” Since it “targets a scientific theory”, about how physical objects behave, “perhaps it belongs more properly to science”, but, Law continues, “the same armchair method employed by Galileo is also regularly employed by philosophers”.

And just as often by scientists. And so both science and philosophy are about concepts, and there is no clear demarcation between them. Such a view is also advocated by Mariam Thalos, who writes: “I propose to use the label science for all of what Aristotle would have called knowledge. Hence it applies to anything that accepts the authority of a coherent set of standards that aim at truth. […] Thus, philosophy is a science”.

In contrast, Massimo Pigliucci attempts to draw clear distinctions between philosophy and science, boldly declaring:

I would go as far as to challenge my scientistically inclined colleagues who contributed to this volume to show me a single instance of systematic observation or experiment (i.e., an example of science) throughout this collection of essays. The contributions Maarten and I collected here are so inherently philosophical in nature that they stand as a self-evidence refuation that science is our only path to knowledge and understanding.

Here, Pigliucci explicitly limits science to: “systematic observation or experiment”, overlooking the entire conceptual, theoretical and model-building side of science. Yes, if you limit science to only that aspect, then that impoverished and neutered hemi-science would be inadequate on its own. You do indeed need all the different styles, working in concert, to do the best science, and that includes the conceptual analysis characteristic of Boudry & Pigliucci’s book of essays.

Pigliucci replies that such a broad conception of science amounts to: “redefining science in a way that is coextensive with reason itself, which is not only historically and factually grossly inaccurate but ultimately meaningless”.

But I deny that it is meaningless, instead it points to a consilience that is a necessary part of seeking out knowledge. None of the “styles” succeeds on its own. One cannot define science as being limited to “systematic observation or experiment” while excluding the conceptual and model-building side of science that is needed to interpret the observations and experiments; such a science would not function.

Philosophers themselves agree with this, pointing to the inevitably “theory-laden” nature of even simple observations. The Quinean-web view of science — with a constant iteration between observation and experiment, on the one hand, and a “web of ideas” on the other — demands that science be just as much about the “web of ideas” as about the observation and experiment. Thus I would go as far as suggesting that Pigliucci’s attempted demarcation between philosophy and science is not consistent with the nature of science and not consistent with the best philosophical understanding of science.

Part 4: Reductionism

Why do morals need to be justified?

To many people the question in the title will seem peculiar. Of course morals need to be justified! Otherwise, who is to say that the morality of Martin Luther King is any better than that of Pol Pot?

The answer to that, by the way, is “people”. There isn’t anyone else. I return to this theme after catching up with the blog of Michael Nugent, who is currently doing a sterling job leading Atheist Ireland to notable successes.

In a series of posts, Michael responds to a challenge laid down by David Quinn, a Catholic, of the Iona Institute:

That’s all very well, but it doesn’t explain why we are morally obliged to treat other human beings with love, dignity and respect. We might do it because we want to, because we feel like it, because it might serve a useful purpose. But why are we morally obliged to do so? Where does the obligation come from? Certainly not from nature.

David Quinn is right! Continue reading

Moral realism versus hypothetical imperatives

Moral realism is the doctrine that there are “moral facts”. Moral facts are declarations of what is or is not moral (“Stealing is morally wrong”) or what we ought or ought not do (“We ought to abolish the death penalty”). In order to be “facts”, these statement have to describe objective features of the world, and so be independent of subjective human opinion on the matter. In order to be “moral” facts (as opposed to other sorts of facts), they need to declare what, morally, we ought to do or not do.

I’m an anti-realist. As I see it, the only form of “oughtness” that actually exists, is instrumental oughtness. That is, statements of the form “If you want to attain Y, you ought to do X”. Such statements, termed hypothetical imperatives by Kant, can be objectively true descriptions of how things are. The statement “If you want to attain Y, then you ought to do X” can be re-phrased as “Doing X will attain Y”, which can indeed be a true fact about the world. Continue reading

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

Science Unlimited, Part One: Pseudoscience

Philosophers Maarten Boudry and Massimo Pigliucci have recently edited a volume of essays on the theme of scientism. The contributions to Science Unlimited? The Challenges of Scientism range from sympathetic to scientism to highly critical.

I’m aiming to write a series of blog posts reviewing the book, organised by major themes, though knowing me the “reviewing” task is likely to play second fiddle to arguing in favour of scientism.

Of course the term “scientism” was invented as a pejorative and so has been used with a range of meanings, many of them strawmen, but from the chapters of the book emerges a fairly coherent account of a “scientism” that many would adopt and defend.

This brand of scientism is a thesis about epistemology, asserting that the ways by which we find things out form a coherent and unified whole, and rejecting the idea that knowledge is divided into distinct domains, each with a different “way of knowing”. The best knowledge and understanding is produced by combining and synthesizing different approaches and disciplines, asserting that they must mesh seamlessly. Continue reading

Does the problem of induction defeat scientism?

Quillette magazine recently published a piece written by Spencer Hall giving: “The Philosophical Case against Scientism”. He begins:

Scientism is the claim that science is the only source of knowledge.

Let’s accept this definition, though it’s important to note that no-one defending such a thesis would interpret “science” in a narrow sense, but would regard it broadly as including the gathering of empirical evidence and rational analysis and conceptualising about that evidence. Thus, “scientism” would not, for example, deny that historians can generate knowledge, it would instead claim that they are doing so using methods that are pretty much the same as those used also by scientists. The differences in approach then arise from the pragmatics of what sort of evidence is accessible, not from their being distinct and separate “ways of knowing”.

The philosophical case that Hall presents is based on the problem of induction. No amount of observing a regularity proves that it will still hold tomorrow. The supposition that it will requires a “uniformity of nature” thesis that the future will be like the past, and since we cannot obtain empirical evidence from the future, that thesis — it is claimed — cannot be proven by science. Continue reading

On Michael Shermer’s defence of moral realism

“Is there anyone (other than slave holders and Nazis) who would argue that slavery and the Holocaust are not really wrong, absolutely wrong, objectively wrong, naturally wrong?”

Yes, I would (and I don’t think I’m either a slave holder or a Nazi). That quote ends Michael Shermer’s recent defence of moral realism on his Skeptic blog.

My disagreement with Shermer comes down to what we even mean by morality being “objective” rather than “subjective”. Indeed this particular disagreement can account for a lot of people talking past each other. Shermer explains: Continue reading

The cosmological multiverse and falsifiability in science

The cosmological “multiverse” model talks about regions far beyond the observable portion of our universe (set by the finite light-travel distance given the finite time since the Big Bang). Critics thus complain that it is “unfalsifiable”, and so not science. Indeed, philosopher Massimo Pigliucci states that instead: “… the notion of a multiverse should be classed as scientifically-informed metaphysics”.

Sean Carroll has recently posted an article defending the multiverse as scientific (arXiv paper; blog post). We’re discussing here the cosmological multiverse — the term “multiverse” is also used for concepts arising from string theory and from the many-worlds interpretation of quantum mechanics, but the arguments for and against those are rather different. Continue reading