Confusion over causation, both top-down and bottom-up

I’m becoming convinced that many disputes in the philosophy of science are merely manufactured, arising from people interpreting words to mean different things. A good example is the concept of “reductionism”, where the meaning intended by those defending the concept usually differs markedly from that critiqued by those who oppose it.

A similar situation arises with the terms “top down” versus “bottom up” causation, where neither concept is well defined and thus, I will argue, both terms are unhelpful. (For examples of papers using these terms, see the 2012 article “Top-down causation and emergence: some comments on mechanisms”, by George Ellis, and the 2021 article “Making sense of top-down causation: Universality and functional equivalence in physics and biology”, by Sara Green and Robert Batterman.)

The term “bottom-up” causation tends to be used when the low-level properties of particles are salient in explaining why something occurred, while the term “top-down” causation is used when the more-salient aspect of a system is the complex, large-scale pattern. But there is no clear distinction between the two, and attempts to propose one usually produce straw-man accounts that no-one holds to.

What counts as evidence? Or why Bayesian analysis of religion convinces no-one.

When arguing about religion on Twitter, there’s a common notion that if (say) consciousness is more expected under theism than under atheism, then consciousness is “evidence for” theism. The argument is that, while an atheistic universe might develop conscious life, equally an atheistic universe could be utterly devoid of life. In contrast, a universe founded by the Abrahamic god would always include God-created conscious life. Hence, consciousness is better predicted by theism and is thus evidence for theism.

I regard this as cheating. The Abrahamic-god hypothesis was designed to explain conscious life. You can’t use known information to construct a hypothesis, and then evaluate your hypothesis as probable just because it explains that very same information.

If the hypothesis successfully predicts new information, not already used in constructing that hypothesis, then, yes, that’s strong evidence. But if the information is not new, then one needs to fall back on evaluating the competing explanations overall. I do not regard “consciousness was put there by God” as being a better explanation for consciousness than “consciousness evolved because it aided animals’ survival”, and thus do not regard consciousness as evidence for theism.

Human brains have to be deterministic (though indeterminism would not give us free will anyhow)

Are human brains deterministic? That is, are the decisions that our brain makes the product of the prior state of the system (where that includes the brain itself and the sensory input into the brain), or does quantum indeterminacy lead to some level of uncaused randomness in our behaviour? I’ll argue here that our brains must be largely deterministic, prompted by being told that this view is clearly wrong.

First, I’ll presume that quantum mechanics is indeed indeterministic (thus ignoring hidden-variable and Everettian versions). But the fact that the underlying physics is indeterministic does not mean that devices built out of quantum-mechanical stuff must also be indeterministic. One can obtain a deterministic device simply by averaging over a sufficient number of low-level particle events. Indeed, that’s exactly what we do when we design computer chips. We build them to be deterministic because we want them to do what we program them to do. In principle, quantum fluctuations in a computer chip could affect its output behaviour, but in practice a minimum of ~50 electrons are involved in each chip-junction “event”, which is sufficient to average over probabilistic behaviour such that the likelihood of a quantum fluctuation changing the output is too small to be an issue, and thus the chip is effectively deterministic. Again, we build them like that because we want to control their behaviour. The same holds for all human-built technology.

Confusion about free will, reductionism and emergence

Psychology Today has just published: “Finding the Freedom in Free Will, with the subtitle: “New theoretical work suggests that human agency and physics are compatible”. The author is Bobby Azarian, a science writer with a PhD in neuroscience. The piece is not so much wrong — I actually agree with the main conclusions — but is, perhaps, rather confused. Too often discussion in this area is bedevilled by people meaning different things by the same terms. Here is my attempt to clarify the concepts. Azarian starts:

Some famous (and brilliant) physicists, particularly those clearly in the reductionist camp, have gone out of their way to ensure that the public believes there is no place for free will in a scientific worldview.

He names Sabine Hossenfelder and Brian Greene. The “free will” that such physicists deny is “dualistic soul” free will, the idea that a decision is made by something other than the computational playing out of the material processes in the brain. And they are right, there is no place for that sort of “free will” in a scientific worldview.

Replying to Adam Frank and defending scientism

“I am a passionate scientist who is passionate about science, but I also think scientism is a huge mistake”, writes Adam Frank, an astrophysicist at the University of Rochester, in an article in The Big Think. As another astrophysicist, who has called this blog “defending scientism”, I am inspired to reply.

Adam Frank, Professor of Astrophysics and advocate of science.

Such disputes can boil down to what one means by the word “scientism”. Professor Frank quotes one definition as “the view that science is the best or only objective means by which society should determine normative and epistemological values”. On that definition I also would reject scientism (indeed I don’t think that anyone does advocate that position). Science cannot prescribe values or aims. Science is descriptive, not prescriptive, it gives you knowledge, not normativity (instead, values, aims and normativity can only come from humans).

Does quantum indeterminism defeat reductionism?

After writing a piece on the role of metaphysics in science, which was a reply to neuroscientist Kevin Mitchell, he pointed me to several of his articles including one on reductionism and determinism. I found this interesting since I hadn’t really thought about the interplay of the two concepts. Mitchell argues that if the world is intrinsically indeterministic (which I think it is), then that defeats reductionism. We likely agree on much of the science, and how the world is, but nevertheless I largely disagree with his article.

Let’s start by clarifying the concepts. Reductionism asserts that, if we knew everything about the low-level status of a system (that is, everything about the component atoms and molecules and their locations), then we would have enough information to — in principle — completely reproduce the system, such that a reproduction would exhibit the same high-level behaviour as the original system. Thus, suppose we had a Star-Trek-style transporter device that knew only about (but everything about) low-level atoms and molecules and their positions. We could use it to duplicate a leopard, and the duplicated leopard would manifest the same high-level behaviour (“stalking an antelope”) as the original, even though the transporter device knows nothing about high-level concepts such as “stalking” or “antelope”.

Science does not rest on metaphysical assumptions

It’s a commonly made claim: science depends on making metaphysical assumptions. Here the claim is being made by Kevin Mitchell, a neuroscientist and author of the book Innate: How the Wiring of Our Brains Shapes Who We Are (which I recommend).

His Twitter thread was in response to an article by Richard Dawkins in The Spectator:

Dawkins’s writing style does seem to divide opinion, though personally I liked the piece and consider Dawkins to be more astute on the nature of science than he is given credit for. Mitchell’s central criticism is that Dawkins fails to recognise that science must rest on metaphysics:

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.

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).

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.