Tag Archives: scientific method

Science is a product of science!

The latest issue of Free Enquiry magazine contains several articles about philosophy and science, including an article by Susan Haack, a philosopher of science who “defends scientific inquiry from the moderate viewpoint”, rejecting cynical views that dismiss science as a mere social construction, but also rejecting “scientism”.

While Susan Haack talks quite a bit of sense about science, she promotes a view that is common among philosophers of science but which I see as fundamentally wrong. That is the idea that science and the scientific method depend on philosophical principles that cannot be justified by science, but instead need to be justified by philosophy.

In the Free Enquiry piece she writes:

… It isn’t true that science can explain everything. The achievements of science certainly deserve our respect and admiration. But, like all human enterprises science is fallible and incomplete, and there are limits to the scope of even the most advanced and sophisticated future science imaginable.

We should distinguish between two claims here. First, can science “explain everything”? Probably not, there are many things that humans can never know, and our understanding will always be limited and fallible. The second claim, though, is that where science is limited in scope, other “ways of knowing”, such as philosophy, can arrive at reliable knowledge. It is this second claim, not the first, that scientism denies.

(It’s also worth pointing out that advocates of scientism intend a broad definition of science that includes rational analysis as much as empirical data, and thus encompasses modes of enquiry that others might regard as outside science.)

Haack continues:

Evolutionary psychology, for example, might tell us a good deal about the origin of the moral sentiments or the survival value of altruism; but it couldn’t tell us whether or, if so, why these sentiments, or this disposition to help others, could constitute the basis of ethics. Cognitive science might tell us a good deal about people’s tendency to notice and remember positive evidence and to overlook or forget the negative; but it couldn’t tell us what makes evidence positive or negative, or what makes it stronger, what weaker. Neuroscience might tell us a good deal about what goes on in the brain when someone forms a new belief or gives up an old one; but it couldn’t tell us what believing something involves, or what makes a belief the belief that 7+5=12 rather than the belief that Shakespeare’s plays were really written by Francis Bacon, or what evidence warrants a change of belief.

I would say that all of the above questions are properly within the scope of science. Haack gives no argument for why they aren’t. But the focus of this post is a more general point about science itself:

More generally, none of the sciences could tell us whether, and if so, why, science has a legitimate claim to give us knowledge of the world, or how the world must be, and how we must be, if science is to be even possible.

This is the claim that science rests on the foundations of philosophy. Haack makes this more explicit:

And the rising tide of scientistic philosophy not only threatens to leave the very science to which it appeals adrift with no rational anchoring; it also spells shipwreck for philosophy itself.

Thus, Haack claims, science is rationally anchored in, and justified by, philosophy, without which it is “adrift”. This account is popular among philosophers of science.

I consider it to be fundamentally wrong. Scientists don’t look to philosophers to justify their subject, they consider that science is justified because it works. And by “works” we mean that it leads to predictions of eclipses that come true, it leads to medicines that can cure people, it leads to accounts of reality that demonstrably contain understanding of the world. This is best demonstrated by technology. Computers work, iPhones work, aircraft fly, MRI scanners work.

Science can use its most esoteric theories to predict the existence of gravitational waves emitted by colliding neutron stars or black holes — both exotic concepts far beyond the world of everyday experience — and then build hugely complex machines of impressive technological mastery to detect such waves, and then use them to observe exactly what was predicted, complete with the characteristic in-spiral pattern.

Further the methods of science are not the product of philosophy but are themselves the product of science. By that, I mean that the methods of science are the product of experimentation, trying out different approaches and seeing what works best.

Science doesn’t reject divining tea leaves, for example, owing to instructions from philosophers, it rejects divining tea leaves because it doesn’t work. The realisation of human biases, and of the placebo effect, and the consequent move to double blinding in medical trials was again not the result of philosophical analysis, but was arrived at by assessing evidence. For the most part scientists are unaware of much of philosophy, and usually don’t look to it for guidance as to how to proceed.

But, the philosopher might reply, science rests on many assumptions about how the world works and about the nature of evidence, and it is philosophers who examine those assumptions. To an extent that is true, philosophers do indeed examine and write about such assumptions; but the justification for adopting them comes, not from philosophy, but again from the fact that science works.

If science necessarily adopts assumptions A, B and C, and then science built on such assumptions works in the real world (“works” in the above sense), then that demonstrates that assumptions A, B and C are real-world true. In other words, A, B and C are no longer assumptions but have now been tested and validated by the fact that adopting them works.

(If one wants to retort that, while science assumes A, B and C, it doesn’t actually test them because it could instead adopt P, Q and R, without any resulting change to observations, then this would mean that A, B and C were not necessary assumptions, and thus that they are not key underpinnings of science.)

Thus Haack’s claim that, without philosophy, science would be “adrift with no rational anchoring” is misconceived. Science is not founded on “rational anchoring”, that is, reasoning from key axioms that can be known a priori (and nor is it founded on axioms that can only be taken on faith). Indeed, it can’t be, because philosophy has no way of arriving at a priori knowledge.

Instead, science is an iteration between a whole web of ideas and models, and the comparison of that web of ideas to the real world that we experience empirically through our senses. Science is not anchored in philosophy, it is instead anchored in the empirical world and justified by the fact that it works; that is, by the fact that the ensemble web explains the real world, enables us to make good predictions about the real world, and enables us to develop technology that works.

To Susan Haack’s suggestion that: “none of the sciences could tell us whether, and if so, why, science has a legitimate claim to give us knowledge of the world”, the reply is that it demonstrably works, and that since it does, that shows that it has a legitimate claim on knowledge (since that’s what “knowledge of the world” ultimately means).

This reply is commonly given by scientists, and indeed by some philosophers of science. The reply that “it works” is a scientific reply, since the maxim of adopting what works (in terms of leading to explanatory and predictive power) is the underlying ethos of science. Adopt what works; test it; adapt it to make it work better; test it again.

And it is a good thing that science is not anchored in philosophy, since philosophy itself has no way of justifying its tenets. Contra Haack, the problem would be if science did depend on philosophy, rather than justifying itself by a boot-strap iteration with empirical reality. Because we’d then have no way of establishing whether it had any more validity than other “ways of knowing”.

One can see why some philosophers of science are fond of the idea that philosophy provides the underpinning and intellectual anchoring of science. This would give them a raison d’etre and allow them to claim some of the glory from the overwhelming success of science.

Philosophy of science is of course, when done well, a valuable commentary about science. I certainly don’t want to dismiss all of philosophy of science (indeed, this post could itself be regarded as philosophy of science). Some commentary by the best philosophers is very insightful. But philosophy is not necessary to science, since on the whole scientists are better than philosophers at deducing which methods do and do not work in finding out about the real world; after all they have by far the best track record of so doing.


Reductionism and Unity in Science

One problem encountered when physicists talk to philosophers of science is that we are, to quote George Bernard Shaw out of context, divided by a common language. A prime example concerns the word “reductionism”, which means different things to the two communities.

In the 20th Century the Logical Positivist philosophers were engaged in a highly normative program of specifying how they thought academic enquiry and science should be conducted. In 1961, Ernest Nagel published “The Structure of Science”, in which he discussed how high-level explanatory concepts (those applying to complex ensembles, and thus as used in biology or the social sciences) should be related to lower-level concepts (as used in physics). He proposed that theories at the different levels should be closely related and linked by explicit and tightly specified “bridge laws”. This idea is what philosophers call “inter-theoretic reductionism”, or just “reductionism”. It is a rather strong thesis about linkages between different levels of explanation in science.

To cut a long story short, Nagel’s conception does not work; nature is not like that. Amongst philosophers, Jerry Fodor has been influential in refuting Nagel’s reductionism as applied to many sciences. He called the sciences that cannot be Nagel-style reduced to lower-level descriptions the “special sciences”. This is a rather weird term to use since all sciences turn out to be “special sciences” (Nagel-style bridge-law reductionism does not always work even within fundamental particle physics, for which see below), but the term is a relic of the original presumption that a failure of Nagel-style reductionism would be the exception rather than the rule.

For the above reasons, philosophers of science generally maintain that “reductionism” (by which they mean the Nagel’s strong thesis) does not work, and on that they are right. They thus hold that physicists (who generally do espouse and defend a doctrine of reductionism) are naive in not realising that.

“The underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are thus completely known, and the difficulty is only that the exact application of these laws leads to equations much too complicated to be soluble.”     — Paul Dirac, 1929 [1]

The problem is, the physicists’ conception of reductionism is very different. Physicists are, for the most part, blithely unaware of the above debate within philosophy, since the ethos of Nagel-style reductionism did not come from physics and was never a live issue within physics. Physicists have always been pragmatic and have adopted whatever works, whatever nature leads them to. Thus, where nature leads them to Nagel-style bridge laws physicists will readily adopt them, but on the whole nature is not like that.

The physicists’ conception of “reductionism” is instead what philosophers would call “supervenience physicalism”. This is a vastly weaker thesis than Nagel-style inter-theoretic reduction. The physicists’ thesis is ontological (about how the world is) in contrast to Nagel’s thesis which is epistemological (about how our ideas about the world should be). Continue reading

Contra theologian Roger Trigg on the nature of science

scientismRoger Trigg is a senior theologian and philosopher. His new book, “Beyond Matter”, is soon to be published by the Templeton Press, part of the wealthy Templeton Foundation whose aim is to produce a religion-friendly version of science.

Roger Trigg

An excert from the book promotes a view of science that is common among philosophers. Those of us with a scientistic perspective see it as erroneous, and yet, since Trigg’s account of science is widely accepted, it is instructive to rebut it.

Trigg argues that science rests on metaphysical assumptions:

What then has to be the case for genuine science as such to be possible? This is a question from outside science and is, by definition, a philosophical — even a metaphysical — question. Those who say that science can answer all questions are themselves standing outside science to make that claim. That is why naturalism — the modern version of materialism, seeing reality as defined by what is within reach of the sciences — becomes a metaphysical theory when it strays beyond methodology to talk of what can exist. Denying metaphysics and upholding materialism must itself be a move within metaphysics. It involves standing outside the practice of science and talking of its scope. The assertion that science can explain everything can never come from within science. It is always a statement about science.

This view can be summarised by the “linear” schematic:


One can see why theologians like this account of science. If it were really true that science rested on metaphysical assumptions then science would be in big trouble, since no-one has ever proposed a good way of validating metaphysical assumptions. Continue reading

A scientific response to the Brain in a Vat

Scientia Salon is an enjoyable webzine discussing philosophical matters, which recently addressed an old conundrum: how do we know we are not a brain in a vat? As I see it, this question is straightforwardly answered by the usual scientific method, so here I’ll summarise the argument that I advanced in the Scientia Salon discussion.

The Matrix-style scenario, which dates back to the skepticism of Descartes, supposes that we are a brain kept alive in a vat, being fed with a stream of inputs generated by an Evil Genius. Everything that we experience as sense data is not real, but is artificially simulated and fed to us. Since, ex hypothesi, our stream of experiences is identical to that in the “real world” explanation, we cannot know for sure whether or not we are such a brain in a vat.

How to respond? First, the whole point of science is to make sense of our “stream of experiences”. We do that by looking for regularities and patterns in those experiences, and we develop those into descriptions and explanations of the world (I’ll use the term “world” here for the sum of those experiences, regardless of whether they derive from our contact with a real world, or from a simulated world being fed to us). Continue reading

Applying falsifiability in science

Falsifiability. as famously espoused by Karl Popper, is accepted as a key aspect of science. When a theory is being developed, however, it can be unclear how the theory might be tested, and theoretical science must be given license to pursue ideas that cannot be tested within our current technological capabilities. String theory is an example of this, though ultimately it cannot be accepted as a physical explanation without experimental support.

Further, experimental science is fallible, and thus we do not immediately reject a theory when contradicted by one experimental result, rather the process involves the interplay between experiment and theory. As Arthur Eddington quipped: “No experiment should be believed until it has been confirmed by theory”.

Sean Carroll recently called for the concept of falsifiability to be “retired”, saying that:

The falsifiability criterion gestures toward something true and important about science, but it is a blunt instrument in a situation that calls for subtlety and precision.

Meanwhile, Leonard Susskind has remarked that:

Throughout my long experience as a scientist I have heard un-falsifiability hurled at so many important ideas that I am inclined to think that no idea can have great merit unless it has drawn this criticism.

Continue reading

Jon Snow, climate change, and the nature of science

Channel 4 News tonight gave extensive coverage to the widespread flooding in England, the wettest spell for two hundred years we’re told. The senior news anchor, Jon Snow, was interviewing Andrew McKenzie, a hydrogeologist with the British Geological Survey:


Snow: Answer me the question that everyone keeps asking. Is this caused by climate change?

McKenzie: Well … quite probably.

Snow: I like that answer, but of course it’s not a scientific answer is it?

Aaargh! Obviously we’re getting nowhere in educating the public about science if a leading journalist such as Jon Snow thinks that being uncertain is “unscientific”, when in reality being uncertain is exactly the scientific response to partial and unclear evidence. Continue reading

Tools of science: Induction and Occam’s razor

As philosophers are fond of pointing out, induction is logically unsound: no track record, however lengthy, of observing that swans are white can validate the conclusion that all swans are certainly white and that no-one will ever encounter a black swan. Yet science uses induction every day, and it works. Our sampling of information is always partial, and yet that partial information tells us enough about the world around us to generate highly successful predictions and to produce engineering and technology that works. One can thus ask on what basis science uses the principle of induction.

Some would argue that induction is an example of a basic assumption of science that cannot be further justified. They might claim that all “ways of knowing” depend on such unverified assumptions, that science is just one example of such a system, and that other assumptions can lead to equally valid domains of understanding, such as theology.

A scientist, though, would argue that tools of science such as induction are not arbitrary, but are themselves justified by science. The scientific method is itself the product of science, deriving from a long historical process of working out what works. Thus, by bootstrapping, science arrives at methods that produce good predictions about the world, and produce engineering and technology that works. Continue reading