Is the idea of a causal chain physical (or even scientific)?

Question

I am aware that the idea is venerable, going back through Lucretius to the Stoics and Epicurus, and even to Aristotle with his prime mover argument. But isn't this a pre-scientific notion? The Atomists thought that collisions cause motion. But that's only half right. Collisions are where an exchange of motion (momentum, energy) happens. A collision assumes there's already some kinetic energy--i.e. motion-- in the system of particles that are colliding. So saying collisions cause motion doesn't explain much. Of course, the Greeks didn't know all this, and it's no fault of theirs.

Look at how the concept of cause usually makes an appearance in physics. Typically, it only appears implicitly. There is talk of certain effects, like the Hall effect, the Mossbauer effect, the Zeeman effect, etc. Following philosophical tradition, and the normal meaning of the word effect, each of these effects presumably has some cause. For the Zeeman effect the "cause" is applying a magnetic field where there previously wasn't one, resulting in the splitting of atomic spectral lines. I think a fairly general definition of cause used this way in physics is a change in the degree of constraint. It could be the complete removal of a constraint, such as removing a partition that is confining a gas to one side of a container. Or it could be applying a "constraint" such as an external field.

The physical explanation of such effects is not a long list of "laws" of the form "A causes B", "B causes C", "C causes D", etc. Instead, a physical theory is developed in which the laws of evolution of the system take the form of equations (usually differential equations). You solve the equations under one constraint (boundary conditions, forcing functions, etc.), solve them again under the changed constraint, and see how the resulting behaviors are different. That is the explanation of the "effect". Physical explanations are not of the form "this domino knocks over that domino, which then knocks over this other one, which in turn..." In fact, Bertrand Russell pointed out that once you have a developed physical theory, you can completely do without talk of causes and effects. There are only regularities.

In spite of this situation, when people begin to reason philosophically, they start talking about causal chains. Maybe it's out of respect for tradition. They do it even when they are trying to be hard-nosed scientific types--trying to explain mental events in terms of physical events without resorting to dualism. And they nearly always assume that physical causes are the only kind of causes that could really matter in a scientific explanation of anything. But how can this be, when talk of causes only rarely arises in physics, and talk of "causal chains" is practically nonexistent? Won't this imprecision inevitably lead to confusion?

Answer 1

I see two factors at play. First our cognitive bias to structure the world in terms of intentions, those of ourselves & others. And supervenient explanatory layers, where units in those layers are causes in their own terms, but the layer is constituted fundamentally or reducibly of the physicists world of regularities.

We learn physical skills and the use of our bodies in large part through the action of complexes of mirror neurons, which activate motor control areas in our brains from watching an action, that we would need to perform it, we mentally project our own body into the position of others for physical insight. More broadly, we learn from Dunbar's number that the close correlation for mammal species of brain size with social group size, indicates much or most of our brain development has been for social complexity, and theory of mind - and of intentions of others. Our brains are wired to make sense of the world as composed of identities with intensions. Be call the results of the intensions of others what they caused. We might expect non-social cephalopod intelligence to differ, for instance. And it's interesting to note 1 in 4 engineers have someone in their immediate family on the autistic spectrum, and that is characterised largely as an impairment of theory-of-mind.

Because it is a cognitive bias, does not mean grouping the world into identities with intensions or teleological aims isn't useful, in particular it can help make things tractable. The extreme example is predicting other humans, we accept they are made of atoms obeying laws but that is not a tractable way to interact, but heuristics like character are, and exist in a self-consistent explanatory layer with it's own terms. More generally this is very useful for learning from fragmentary data about complex systems.

Our mode of thinking about particles is to see them as like individuals, with a story. What our real understanding says, is that transformations are happening with certain probabilities, that maintain the relevant conserved quantities. A Feynman diagram is like a story, and the sum-over-histories assembles the possible stories, and that gives us insight into general behaviour.

We interpret the principle of least action, and increasing entropy, as part of the character of the universe. As we assemble the stories of systems, we picture these as causal, as having teleological intensions to maintain themselves. But fundamentally we just have patterns, and these are heuristics, which we must be careful to keep in their own relevant explanatory layer.

Noether's theorem shows us that conservation laws are symmetries under transformation, that these are dimensions. Particles are local consistencies in the transformations. The symmetries are literally a pattern, in the structure of physical laws, an efficient abstraction of experiences which narrows possibilities, making prediction forwards and backwards (far more) tractable.

'Causal' can definitely become problematic if it gets outside of it's layer. We have the pathetic fallacy, at the level of everyday experience. In science there is a huge risk of accepting a narrative explanation because it 'makes sense', which usually means conforms with our sense of the character of a system. Underestimating the impact of exponentials, and over-estimating the regularity of one off events, are known risks there. We have to actively find ways to check and counteract these biases in assembling narratives. But, identifying locii within systems and 'telling their stories' is powerfully useful.

Answer 2

The Atomists thought that collisions cause motion. But that's only half right. Collisions are where an exchange of motion (momentum, energy) happens. A collision assumes there's already some kinetic energy--i.e. motion-- in the system of particles that are colliding. So saying collisions cause motion doesn't explain much.

That collisions cause motion is obvious. Physics gives us a deeper and more comprehensive account, but it does not deny the obvious.

The word cause is usually not itself a scientific term, although it can be translated to scientific terms. Even with the ancients, we can see that the use of causal language is often independent of specific physical theories. Thus we can see in Cicero's On Fate Aristotelians, Atomists and Stoics debate on causal chains in the context of fate (i.e. determinism) where each party believes in a different physics.

a physical theory is developed in which the laws of evolution of the system take the form of equations (usually differential equations) … Physical explanations are not of the form "this domino knocks over that domino, which then knocks over this other one, which in turn..."

But surely even physicists occasionally talk in such terms as "A knocks over B". It is that they know how to translate the causal language, when needed, into the up to date physical terms.

In fact, Bertrand Russell pointed out that once you have a developed physical theory, you can completely do without talk of causes and effects. There are only regularities.

Bertrand Russell is indeed relevant here. He didn't just comment on the present subject, the usefulness of the concept of cause in the face of modern physics. He wrote a seminal essay about it - On the Notion of Cause (1912)

The reduction of causation to regularities (regular succession) is due earlier, in the classic treatment of causality by David Hume. It is worth mentioning that it has been argued, against this reduction, that not all regularities are causal. One classic example is the regular succession of day, night, day, night, etc. Whereas day does not cause night, and vice versa.

In spite of this situation, when people begin to reason philosophically, they start talking about causal chains … But how can this be, when talk of causes only rarely arises in physics, and talk of "causal chains" is practically nonexistent? Won't this imprecision inevitably lead to confusion?

Not inevitably. Causal talk is often useful, and precise enough. It can often be unproblematically translated into modern physical terms, where needed.

Answer 3

There are competing views, e.g. Russell's belief that 'causation' is harmful, vs Cartwright's that without 'causation' science would be "crippled"

https://www.oxfordhandbooks.com/view/10.1093/oxfordhb/9780199284221.001.0001/oxfordhb-9780199284221-e-15

I think calling either view a "folk" belief is really quite misleading. As far as I know, everyone who believes in the "causal relation" would also believe in a "causal chain", though unlikely with its historical baggage.

What is the metaphysical basis for causal connection? That is, what is the difference between causally related and causally unrelated sequences?

The question of connection occupies the bulk of the vast literature on causation. One finds analyses of causation in terms of nomological... agential manipulability... contiguous change ... physical processes... and property transference... One also finds views that are hybrids of some of the above... and even eliminativism (Russell 1992, Quine 1966).

https://plato.stanford.edu/entries/causation-metaphysics

The difference between a regularity and causal connection is a hot topic in philosophy of science

Answer 4

You misunderstand Aristotle's metaphysics, as well as his prime mover argument.

Aristotle's prime mover:

God (the prime mover) necessarily exists. Because:

I. Something cannot be the efficient cause of itself. a) If A exists, another caused it (another necessarily caused the potential of its existence to become reality).

II. A thing's continued existence is potential, for it is not actual. b) Therefore if A continues to exist, another keeps causing it.

III. Therefore, as everything continues to exist, God (the prime mover) exists, continually and without change (if God changes from potence to act, another would have to cause Him, wherefore we conclude that God is an immutable, eternal, unchanging substance from eternity).

Now, as for the physicality of the causal chain, Aristotle's causality is metaphysical so it is above the realm of physics. His thought is not lower than current scientific thought, but in a higher and more abstract sphere.

You are confusing physical "causation" -- the interaction between physical substances -- with metaphysical "causation," or the movement of potence to act.

Answer 5

For me Leibniz's ideal rationalism can easily explain that the apparent causality in the realm of our perceived physical world is nothing but an illusion from the underlying objects' coordination. The common view of causality is nothing but an "interaction" influence chain between different objects as time unfolds, but Leibniz's Monadology clearly visualizes it in a completely alternative way as mere "synchronization" of all windowless substances (he called monads), there's no interaction or influence between substances at all ontologically. This philosophy also completely avoids the entangled mind-body dualism such as espoused by Descartes.

An example in object-oriented computer design can easily describe this non-causal process, since the whole software is nothing but composed of numerous objects each having its own properties and methods pre-coded. So when u hit a submit button, you "feel" from your sense organs that your clicking-a-button event "causes" your paragraph to be saved in the server's database. However, what's really going on is the button object code is just "called back" within its own pre-established laws in order to collect your data and send it out, and after receiving serialized data from internet, the backend database is also just "invoked" within its own table object's code to further deserialize and persist data to drive, be it MySQL or Oracle.

Using computer science jargon, there're no actions/reactions, there're only callbacks. This view has derived a major flexible programming pattern called Event Drive architecture used almost everywhere now.

Of course per Leibniz there's true "final cause" of a substance he called Entelechy borrowed from Aristotle which sits beyond the laws of physics and only accessible to its creator, this also make sense by easily expanding previous analogy as the programmer can always come back and change object's code even during runtime for some programming language...

Answer 6

In a Kantian vein: causes and effects form a sort of "chain" because time itself is represented by a linear structure. We synthesize events over time according to causality so that causes at time A yield effects at time B (note that Kant mentions simultaneous cause/effect situations in the discussion of causality itself, which are relevant to his additional principle of physical community; here the chain metaphor is compromised by having A = B, but maybe we can revive the metaphor by reference to the integrity of two halves of a chain link itself).

As a metaphor, the notion of causal chains can be interchanged with that of causal dominoes (as you bring up) or other things (causal Rube Goldberg machines, maybe). These are images/examples, of temporal structure, which seems physical enough as a concept ("events in time are regularly synthesized" doesn't seem counterphysical or counterscientific, anyway).