(this post has been edited on 14 Nov 2023 based on comments received at the time)


Emergence is widely discussed in the context of what could be called bio-philosophy ("Where does life come from?") and existential philosophy ("What is consciousness?"). The concept is invoked to save physicalism from its reductionist contradictions and conjure up a physicalist world view where life can sprout out of a primordial soup, and where animals can play Beethoven's 5th.

A belief in some inherent capacity or propensity for emergence in this world, is supposedly all it takes to explain how one can get from a primordial soup to a symphony (and other cultural goods) in 4 billion years, without using the easy cop-out of a god of the gaps.

In spite of its good fortune, the concept is rarely examined philosophically, to my satisfaction anyway. One of the recent contributions there, by Mark Bedau, was to propose a distinction between weak and strong emergence. This distinction never resonated with me, in part because I don't see that it makes a real difference, and also because I suspect it's a sort of ploy to dismiss the very concept of emergence. (details follow)

So I am asking the double-barreled question: Is the distinction between weak and strong emergence conceptually clear, and if yes, does it make any significant difference?


I haven't found a definition of emergence in the relevant SEP entry. Wikipedia proposes the definition by G. H. Lewes, who coined the term "emergent" in 1875, distinguishing it from the merely "resultant":

Every resultant is either a sum or a difference of the co-operant forces; their sum, when their directions are the same – their difference, when their directions are contrary. Further, every resultant is clearly traceable in its components, because these are homogeneous and commensurable. It is otherwise with emergents, when, instead of adding measurable motion to measurable motion, or things of one kind to other individuals of their kind, there is a co-operation of things of unlike kinds. The emergent is unlike its components insofar as these are incommensurable, and it cannot be reduced to their sum or their difference. (emph. added)

So according to the concept inventor, Lewes, emergence is about what in a system is "more than the sum of its parts" (Aristotle).

To define what he calls "strong emergence", Bedau does not start from Lewes' definition above, but from the "clearly articulated and carefully defended account" by a certain Timothy O'Conner, who defines emergence via the capacity for the emerging stuff to exert downward causation on its elements.

However, downward causation is a higher bar than that set by Lewes, arguably. This may be why Bedau choses O'Conner's definition of emergence tout court for his definition of strong emergence. Another reason is perhaps that his real beef is not with emergence proper, but precisely with the concept of downward causation.

In his essay, he writes of “strong emergence” (i.e. emergence as understood by O'Conner and others) as magical thinking.

Here is how Bedau defines the concept he proposes instead in his essay, weak emergence, which to him his "metaphysically benign":

Macrostate P of S with microdynamic D is weakly emergent iff P can be derived from D and S's external conditions but only by simulation.

Why "only by simulation"? Because Bedau is having in mind a chaotic system, that can "only be simulated" through models and not resolved with a unique mathematical solution. Specifically, he seems to have based much of his idea of weak emergence on the phenomenon of cyclones. A cyclone does not, in his view, exert downward causation, thus it is only weakly emergent.

So is Bedau saying that cyclones are “weakly emergent” “while living beings are “strongly emergent”, then? No, he does not. What he is really saying is that strong emergence (when defined as downward causation) is magic thinking, and thus cannot logically exist as a real physical phenomenon. According to him, you and I are just as weakly emergent as hurricanes.

In other words, to use Lewes’ terminology, he is saying that everything is resultant, nothing is emergent. Nothing ever emerges.


To me, this argument has a number of holes:

  1. Bedau falls well short of defining a new, alternative concept. He merely waves in its general direction, since his ‘definition’ of weak emergence is in fact a condition to verify in order to qualify, not actually a descriptive definition of what the concept means. Apart from being "metaphysically benign" and only amenable to simulation, we are left in the dark as per what this phenomenon exactly is, and have no clear, usable notion of emergence at the end of his essay. So his work leaves us poorer conceptually than where we started from.

  2. He fails to address the power of the feedback loop concept, which implies that high-order, large effects can in turn become regulating causes for what originally affected or created them. This concept is very useful in biology, and is often conceived of as combining downward and upward causation, for instance in population genetics when speaking of ecosystem pressure. So when Bedau argues in his paper that "strong emergence" is not a useful concept in science, he is probably ignoring biology entirely.

  3. To my mind, emergence evokes a slow, progressive growth. It starts small and then it grows progressively. So from that angle, I find the distinction between the weak and strong kinds not germane to the concept. The distinction could prove quantitative rather than qualitative: with time, weak emergence will grow strong...

  4. Indeed, another side of the concept is that this "growth" should build something semi-stable. If something emerged, it's there to stay, at least for a little while. A blip on a screen, that goes on and off in a millisecond, does not really "emerge". There is a certain resilience assumed in emergence.

Hence perhaps O'Conner's definition: is truly emergent what is resilient, what can defend itself against entropy, the force that ultimately destroys all things. This implies the effectiveness of emerging systems (like living organisms) to act causaly for their self-preservation and maintenance. Aka what people call "downward causation".

  1. Arguably (many of the comments to this question refer to that point), the concept of "downward causation" itself is poorly crafted, and thus does not offer a good criterion upon which to define emergence, as O'Conner tried to do, followed by Bedau.

Emergent phenomena emerge out of something, so the concept also calls upon the idea of a background, against which or rather thanks to which a certain thing can emerge. The emerging stuff, if widely replicated, can in turn constitute a new background, upon which another, different kind of emergence may happen. In this sense and as stressed by Ted Wrigley, the emerging stuff both depends on the background and acts on the background. So the phrase “downward causation” is poor wording. The actual idea is intractably reflexive, i.e.:

• small-scale local interactions produce large-scale systemic (emergent) phenomena, and…

• these large-scale systemic (emergent) phenomena affect those small-scale interactions. [I thank Ted for this section]

Another commentator, @Conifold, stressed the idea of causal closure, expressed as follows: “microphysics do not change in collectives”. From this argument, there ought not be anything like “downward causation”, or “upward causation”. There’s just causation.

I agree that physics do not change in collectives, so I accept causal closure. I accept that, when biologists speak of "environmental pressures" it is merely a way of speaking, that animals live or die because of specific things that kill or sustain them. A particular virus got them sick, and then a particular predator ate them, for instance. Nobody ever died of something as general as an "environmental pressure". And yet, we speak of epidemics and we study them. It's a useful manner of speaking.

After all, "upward" and "downward" are subjective terms, in the eye of the beholder. Nature is one, and not divided into levels outside of our mind.

However, I see no contradiction in including steric effects among my cause-to-effect thinking. Stericity is about the shape that chemicals take, eg proteins. This shape is causal, and it is additional to the mere components of a protein, in the sense that one can make different proteins with the same aminoacid components. Certain precise shapes or configurations of elements have the capacity to make microphysics do things that other shapes or configurations cannot do. For instance, the manner in which the components are inserted on a mother board -- their configuration -- will have an important impact on the functionality of any electronic device.

I thus propose to speak of the causal power of structures (including in terms of resilience, i.e. the capacity for self-maintenance and preservation), instead of speaking of “downward causation”. This is intended as more precise wording for the same idea: the idea that certain systems / structures / shapes have different effects than others.

I further propose to base the concept of emergence not on “downward causation” but on the causal power of the emerging shape, including in terms of its resilience power (its capacity to dynamically maintain itself). The stronger this causal power, the stronger the emergence, in coherence with my gradualist view of the concept.

Looking forward to further discussion.

  • this concept, closely resembles many self-organization mechanisms in nature. Nov 11, 2023 at 16:52
  • @IoannisPaizis the two concepts are indeed similar.
    – Olivier5
    Nov 11, 2023 at 20:19
  • 3
    SEP does distinguish strong and weak emergence when giving Kim's argument. There are five properties, of which one, causal closure, is what (all) weak emergentists accept and strong ones deny. Feedback loops no more have (ontological) top down causation than evolution has purposes (as is particularly obvious in electronics), it is a façon de parler fitted to human psychology to simplify initial grasp. Its power is didactic. Real top down causation has been conjectured and tested, but so far the results are negative.
    – Conifold
    Nov 12, 2023 at 7:56
  • 2
    That collective effects can be thought of causally does not make top down causation. Raising temperature causes gas molecules to go faster, but not in the ontological sense of (strong) emergence, same with stericity. Top down causation is when the collective exerts causal powers over and above microcauses, we would see it if probabilities were to deviate from QM predictions in compounds or brains, for example. I do not think there is a spectrum of emergence, either microphysics does not change in collectives or it does. If it does, there is strong emergence, no matter how small the effect.
    – Conifold
    Nov 13, 2023 at 8:20
  • 1
    Laws of microphysics do not change, but the microstate surely changes, just as it changes when water freezes into ice. The change is too complex for us to describe it in fine microscopic detail, so we we opt for more coarse-grained macroscopic descriptions. Those label entire classes of microstate changes, birth, death, phase transition.
    – Conifold
    Nov 13, 2023 at 13:01

9 Answers 9


I don't think the distinction between 'strong' and 'weak' emergence (as laid out here) works philosophically. The issue is scoping; we have to keep our eye on the emergent phenomenon without drifting off to something simpler and more concrete. To use your 'snowflake' example, it's misleading to suggest that snowflakes are unique but have no 'downward' causal power. The uniqueness of an individual flake may not, but the collective effect of countless snowflakes has a strong causal effect on weather and the environment. Frankly, if water never formed snowflakes but solidified straight to blocks of ice, winters in many places would be unsurvivable.

To be more analytic, we have to note that emergent phenomena invariably refer to properties of dynamical systems. There's no such thing as a 'static' emergent phenomenon. Emergent phenomena emerge out of self-referential flux. In this sense the phrase 'downward' causal pressure is poor wording, because the actual idea is intractably reflexive, i.e.:

  • small-scale local interactions produce large-scale systemic (emergent) phenomena, and…
  • these large-scale systemic (emergent) phenomena affect those small-scale interactions recursively.

The recursiveness of the 'downward' causation reinforces the large-scale pattern. Thus a whirlwind begins when a patch of air heats up and expands. This drop in pressure causes the air to rise, drawing in cooler air, which heats up, expands, and rises, drawing in more cool air. The overall pattern of the whirlwind emerges from the rising air, but only because the pattern itself reinforces the pressure differentials that draw in more air.

There's a far more difficult and subtle debate over the question of whether all dynamical systems are non-linear deterministic systems, or whether non-linear, non-deterministic systems might exist.

O'Connor's definition is decent, if jargon-ish. Lewes' definition is dated. Bedau seems to be searching for an angle on the problem that doesn't quite exist. C'est la vie!

  • Thanks, you make good points, which I might integrate in the OP. Every complex system is non determinist, the way I see it. As for Bedau, he is trying to cancel emergence in favor of a weaker, diluted version of the same concept.
    – Olivier5
    Nov 12, 2023 at 10:30

Weak emergence means the emergent properties can be reduced to their component parts. This is something we have heaps of evidence for, like the cathedral shape of termite mounds, the shape of snowflakes, or the flow of traffic. And it also corresponds to how we understand reality and physical systems. Even the most complex operations your computer performs can be reduced to interactions between capacitors and transistors and electricity and such.

Strong emergence suggests there's some step you can take that makes the bigger system irreducible to component parts. As far as I know, that's something we have zero demonstrated examples of. Although that may be because it's unfalsifiable, because you cannot prove that it's impossible for something to be reduced to its component parts (unless maybe systems with identical components behave differently, but that might suggest that there's some additional unknown component). It's pretty much exclusively used as a hypothesis for consciousness (for physicalists that don't accept weak emergence). And it's especially uncompelling given that plenty of things once thought irreducible has later been reduced. Also, it doesn't really make sense on a conceptual level to be able to be able to take a step without being able to see the step that you took.

So yes, those are very different, and the difference is very significant.

And no, physicalism has no need to be "saved from its reductionist contradictions", on account of there not being any contradictions. The evidence suggests that life did indeed sprout out of a primordial soup, and humans are scientifically classified as animals, so animals can indeed play Beethoven's 5th (to be more generous to what you mean: the evidence also suggests that humans are the result of billions of years of evolution, with increasing mental capacity throughout that process, and no clear line we can draw anywhere that would separate conscious animals, and especially not humans, from everything else). Your own incredulity towards this does not mean it's false.

I'm also not sure why you think it's "false" that strong emergence is not a useful concept in science. I'm not aware of any functional purpose that the concept serves in science.

  • Re. The logical contradictions involved in reductionism, I think you and I discussed that already. It's extremely simple: any theory about the human mind is a product of the human mind, and therefore anything it says about mind applies to itself. It follows that reductionism, as a theory, must be reducible to chemistry. Re. Your last question, how much did you study biology?
    – Olivier5
    Nov 17, 2023 at 11:50
  • @Olivier5 Well, a theory's an abstract object that doesn't exist beyond the minds of those aware of it, and thoughts seem to reduce to some neural structure, the firing of neurons, and some chemical soup. So I don't see the problem.
    – NotThatGuy
    Nov 17, 2023 at 12:24
  • @Olivier5 Regardless of whether my knowledge of science justifies believing strong emergence serves no purpose there, all you'd need to do to refute that claim would be to provide a single functional purpose. In response to your edit: the example you offer seems to merely be pluralistic causation, which can still be just weak emergence. If you merely say it's useful to think of it as strongly emerging, then I don't really see the use: conceptually, emergence is emergence, and strong vs weak is a question of how physical systems work, physically, not how you think of them conceptually.
    – NotThatGuy
    Nov 17, 2023 at 12:24
  • If your ideas are generated mechanically by some chemical soup, I for one can see no reason to believe them. As for science, people who have no exposure to biology simply cannot understand what this concept does. People who have been spared the efforts needed to understand photosynthesis or any other enzymatic system have no clue how complicated yet functional it can be. They can afford to see the world and themselves are just some random bunch of atoms spinning and bouncing. Biologists cannot afford that naïvity because they study the question seriously.
    – Olivier5
    Nov 17, 2023 at 13:02
  • @Olivier5 My reasons for believing something would the mostly same regardless of how the brain works: analyse the claim based on its explanatory power and simplicity, and the reliability and our understanding of the method used to obtain it. I don't imagine you'll find that professional scientists or biologists specifically, on average, support strong emergence. Much of science is very specifically about finding reductions. Never mind if we talk about neuroscience, which has gotten a long way towards refuting the various dualist ideas by systematically breaking down how the brain works.
    – NotThatGuy
    Nov 17, 2023 at 13:23

Your question is probing one of the major areas of incomplete thinking within our current model of epistemology.

Weak emergence preserves global reductionism

"Weak emergence" is basically the thesis that emergence is not "real", but instead a stand in for TBD as yet uncharacterized reduction. Your characterization of Bedau's model as basically denying that emergence is more than a mental crutch is correct, and this is one of the major perspectives brought to conceptualizations of emergence. The rationale behind this approach to emergence is to try to preserve an epistemological principle that global reductionism is the only valid way to achieve characterization of our world and phenomenon.

This epistemological thesis, of global reductionism as the sole method of characterizing our world, has been criticized from a variety of perspectives.

Wholism logically matrixes to strong emergence

One of the major critiques has been that reduction fails to actually capture all of the phenomena of our world, and wholism is needed as an additional epistemologic approach. This is what Lewes was arguing for -- that there are aspects of our world that are only understandable wholistically as opposed to reductively. Lewes is arguingtThat there IS more to a whole, than just the sum of its parts. You focused on alternative critiques that assert causal openness vs. closure of physics. I believe if you really trace the idea of wholism vs reductionism, you will find that wholism completely matrixes into "not all causation is characterized at reduced physics." A major current advocate of wholism today is Ian McGilchrist, who has written an opus "The Master and His Emissary" https://www.amazon.com/Master-His-Emissary-Divided-Western/dp/0300188374

Other alternatives to reductionism

Besides wholism, the other pushbacks against global reductionism have included process physics (Whitehead's point that OBJECTS are a secondary part of what we care about in science, it is actually processes that we really need to study, and object-based science fails to capture processes), emergence (which I have argued above transforms into wholism), and pluralism -- the thesis that we infer reality based on successful inferential models, and we know that those models do not currently cohere, and we don't know if they ever will.

Process Science

Whitehead's process science is an intriguing alternative to object-science, but does not actually reject reduction. Whitehead instead tried to reduce science to processes rather than objects. His work does suggest that we don't actually have our conceptual ducks in as clean a row as most philosophy of science presumes, and it serves as a warning that the rationale behind science might not actually close.


The more pertinent alternative perspective is the one that has led to pluralism. There are multiple strands to this perspective.

Logical Pluralism

One strand of support for pluralism has been the demonstration that logic does not cohere, and that our "wish it were so" of logical coherence is not reliable. A major step in this process was Kant's "The Critique of Pure Reason" -- which argued that our study of the world has to assume radical contingency. A later step was when Kant was demonstrated to have been way to OPTMIMISTIC about reasoning, as he offered the "truth" of Euclidian geometry as one of his exceptions to the pure contingency of our world! Godel's demonstration of the inability of logic systems to be able to reliably characterize themselves further undercut rationalism. The culmination of this strand of pluralism is the adoption of logical pluralism as the nature of logic by the majority of logicians today. https://www.cambridge.org/core/journals/think/article/guide-to-logical-pluralism-for-nonlogicians/EDFDFA1C9EB65DB71848DABD6B12D877 If LOGIC does not cohere, then the presumption that our world coheres, becomes highly suspect.

Science does not cohere

Another significant pushback against global reductionism is that the basic process of science, which is to infer reality based on useful model fitting, is a process that leads to non-coherent models as a matter of course. This is articulated in this answer: Can findings in one science contradict those in another? If science is actually NOT coherent, then the inference to a presumption that it will SOMEDAY be coherent -- is actually not supported by empiricism.

This point is made in the SEP article on scientific reductionism, section 5. https://plato.stanford.edu/entries/scientific-reduction/#UnrIss Global reductionism, as a guiding principle, lead to a large amount of integration of physics concepts in the early parts of the 20th century, and the integration of about half of chemistry as an extension of physics, and the characterization of much of biochemistry as an example of chemistry. This time period showed massive utility to the global reduction thesis. BUT -- the progress of reduction of physics to QM and relativity, has mostly stalled for decades. Same with further reductions of chemistry, and almost any reductions of any OTHER sciences to some simpler science. Reductionism as a global claim -- no longer can point to tremendous success as a science presumption. Instead, a period of success, followed by stagnation -- is characteristic of a thesis that is very valid in some fields, but is NOT global in extent! IE -- that there might be multiple (plural) approaches needed to do complete epistemology.

Physics is not closed

One of the key presumptions of physicalism is that physics is causally closed. You assert that as well. But we know that is not true. Physics is stochiometric, and thru chaos phenomena, this stoichiometry leverages up to macro scales.
Deterministic or stochastic universe? Stoichiometry leaves room for emergent phenomenon to be causal, without conflicting with physics.

Science is not justified

One of the other key pushbacks against global reductionism is that global reduction presumes that science is the only valid way to achieve understanding. BUT -- science does not justify itself. Science is just a formalization of empiricism, and empiricism is an informal process that is only justified -- by its empirical success. This is an example of circular reasoning, and the inability of epistemological justifications to avoid the Munchausen Trilemma.

Philosophy, morality, values, reasoning, mathematics, aesthetics, and the humanities are all empirically supported methodologies to characterize our world, and science cannot show that it is able to encompass all of these fields (even the sciences don't reduce to each other!). Plurality of presumptions is -- explicitly justified by the same rationale that justifies the utility of science, and these other fields are MORE useful than science to characterize their important subjects.

Consciousness is the poster child cited for strong emergence by SEP

We all have access to how internal functionalism violates reductionism. I can come up with a thought. I am able to maintain that thought even as my neurons ratchet energizing paths around my brain (thoughts do not reduce to neuronal firing). They do not reduce to neuronal connections either -- we know those connections change all the time, yet we can have the same thought again. We can also communicate this thought successfully to others who have dramatically different neurology, and do so repeatedly with success (schools). None of this makes any sense unless the functions of our thinking are causal on our neurology.

Non-reductive physicalism

These strands of wholism, strong emergence, limitations of coherence and reduction, and our experience of consciousness as a prime example of strong emergence, are why the SEP article on science reduction notes that physicalists for a half century have embraced non-reductive physicalism.

You have pushed back on non-reductive physicalism as well, as what that means is very difficult to characterize. Most non-reductive physicalists also, as you do, hold by causal closure, despite physics being neither logically nor empirically closed. So what non-reductive physicalism could actually mean, is not itself obviously coherent.

Emergence, or pluralism, still need work

What the strands of rationale I have pointed to suggest, is that global reductionism is not valid, and some version of strong emergence is plausible, leading to a pluralism in our world. This evidence case has convinced the large majority of philosophers of mind, and philosophers of science. But the details of either a non-reductive physicalist theory, a theory of strong emergence, or some pluralist ontology, have not been matured to the point they are actually coherent and evaluable yet. The theorizing is still nascent, and flawed.


I take your point that the difference may be a matter of degree or quantity rather than quality. Is there significant difference? Logically, a larger quantity is significantly different from a smaller quantity. Does it make sense to talk only of strong and weak emergence? If we accept this argument, then no. A quantitative scale would make more sense. Your idea seems to be that it starts low and increases. This has merit.

  • 1
    Thanks. Yes, I think it's part and parcel of the concept. Emergence starts weak and then grows stronger over time.
    – Olivier5
    Nov 11, 2023 at 20:18

I'm going to respond just to this specific quote:

To my mind, emergence evokes a slow progressive process, it starts very small and then it grows progressively. So from that angle, I suspect the distinction between the weak and strong kinds to be in fact quantitative rather than qualitative: with time, a lot of weak emergence will grow strong

If we're defining Strong Emergence as when macroscopic objects have Downward Causal Force over their constituent pieces, then what you've said here, I believe, is not the case.

Weak Emergence has no downward causal force. Ever. And if you stick two weakly emergent things together, there's still no downward force. And if you stick 100 weakly emergent things together, there's still no downward force. There's no quantity of weakly emergent things that will change a system from not having downward causation, to having downward causation.

The most tangible example of this is Conway's Game of Life. Weakly emergent things happen in this game. We know it's weakly emergent and not strongly emergent, because we literally have the source code. Gliders are the classic example of weak emergence here.

You can make large scale "machines" in the game that produce gliders.

And you can make larger scale machines that produce machines that produce gliders.

And no matter how many gliders there are, and how many machines making gliders there are, and how many machines there are making machines, we know for a fact that everything that happens in the game is weakly emergent, because we have the source code. Any time someone wants to say "but wait, what about THIS? Isn't this strongly emergent?", you could check. You could check if any of the pixels were acted on from above, by a 'downward force' from an emergent object, and you would always find in Conway's Game that in fact, no, every pixel obeyed all the pixel-level rules all the time without exception. So there's no downward force, ever, in this game, no matter how much weak emergence you have.

That doesn't mean there's no Strong Emergence in our world, but it does mean that Strong Emergence isn't just the natural consequence of a lot of weak emergence. Weak Emergence + Weak Emergence = more weak emergence.

If there is strong emergence in our world, it is a very different beast from weak emergence. I would say the distinction is valid.



A few points were raised in the various conversations appendant to this topic, which I would like to reflect upon here.

One is about the surprising effect or nature of emergence: there's something odd, disruptive about emergence -- eg "the emergence of China on the world scene". It's new AND unexpected, truly new in a sense.

This point is made in different ways. David Chalmers definition of 'weak emergence' (as quoted by @Xtal, emph. added) is a good example: "We can say that a high-level phenomenon is weakly emergent with respect to a low-level domain when the high-level phenomenon arises from the low-level domain, but truths concerning that phenomenon are unexpected given the principles governing the low-level domain."

Which is another way to say that the laws and principles governing the low-level domain fail to account for what happens in an emergent phenomenon.

Ergo, emergent phenomena seem to be governed by some additional laws to those of the background phenomena they emerge from. The background laws probably still apply but others are added.

This was already in Humes's Composition of the Causes:

There is, then, one mode of the mutual interference of laws of na­ture in which, even when the concurrent causes annihilate each other's effects, each exerts its full efficacy according to its own law, its law as a separate agent. But in the other description of cases, the two agen­cies which are brought together cease entirely, and a totally different set of phenomena arise: as in the experiment of two liquids which, when mixed in certain proportions, instantly become a solid mass, instead of merely a larger amount of liquid. This difference between the case in which the joint effect of causes is the sum of their separate effects, and the case in which it is heterogeneous to them; between laws which work together without alteration, and laws which, when called upon to work together, cease and give place to others; is one of the fundamental distinctions in nature. The former case, that of the Composition of Causes, is the general one; the other is always special and exceptional.

It was also there in Lewes, who first used the term in a philosophical sense (see his definition in the OP).

It follows that the concept of 'weak emergence', which in its many forms always amounts to a kind of emergence that would be reductible to the background, is an oxymoron, a contradiction in terms. If emergence worked the same way as its background, it would literally not emerge from it. It would not be different from the background.

This analysis disposes of the concept of 'weak emergence'. Either something emerges, or it does not. If it does, it works differently than the background from which it emerged, by definition. The laws governing or describing the background are insufficient to understand an emerging phenomenon, in the original sense of the word.

Another point aimed in discussions was about the relative importance of biology and physics and their relationships. I have argued for the autonomy of biology vs chemistry and physics, not that the laws of the latter do not apply to living beings, but because life emerged and keeps emerging from inanimate matter in the word's meaning above: life cannot be explained by, or reduced to, chemistry and physics alone.

You can't explain the death of MLK by invoking quarks and only quarks.

I also believe in the centrality of biology as far as this question is concerned. The existence of life, and of sentient life, is what this concept of emergence is primarily meant to describe. Not hurricanes. And I have found the philosophical writings of biologists such as François Jacob and Ernst Mayr most illuminating.

François Jacob wrote in The Logic of Life that "For a long time, the biologist treated teleology as he would a woman he could not do without, but did not care to be seen with in public. The concept of programme has made an honest woman of teleology".

Ernst Mayr provides a less Gallic and more technical description of the same point in Toward a New Philosophy of Biology*, through the example of bird migration:

if we look over the four causations of the migration of this bird once more, we can readily see that there is an immediate set of causes of the migration, consisting of the physiological condition of the bird interacting with photoperiodicity and drop in temperature. We might call these the proximate causes of migration. The other two causes, the lack of food during winter and the genetic disposition of the bird, are the ultimate causes. These are causes that have a history and that have been incorporated into the system through many thousands of generations of natural selection. ... This is the case with almost any biological phenomenon we might want to study.

This puts biology in contrast with physics, where there's no room for any teleology. Electrons don't have millions of years of genetic history stored in them, telling them to fly south in Autumn.

How is this "bio-philosophy" useful? Take the other reason for invoking emergence: the human mind. In a biological, evolutionary framework, two types of questions can be asked about it: 1) how physiologically is it "produced" in a given individual, how does it emerges and re-emerges from the background of cellular (neuronal) biology in his brain, always a bit different than before but always essentially the same? 2) how did the behavior emerge historically over millions of years, how did our species come to be endowed with the capacity to think consciously? And what advantages did it bring, which made our ancestors more apt to survive and reproduce? Because such a big brain comes with biological (metabolic, reproductive) costs, so if brain size was progressively selected (as it seems to have been), it must have brought some advantage... Ergo, the human mind, seen as a biological phenomenon, must be efficacious, causal. Otherwise it wouldn't have emerged historically; this particular biological feature would not have been selected by evolution.

This is how "bio-philosophy" can be useful: by giving some sense to our existence, not as beings "created in the form of God" but as beings that are here for a good Darwinian reason, at least. Call that 'weak teleology'. 😀

Finally, many comments were about "upward and downward causation" in the context of trying to find the limit between "weak and strong emergence". In this framework, "strong emergence" is defined as involving both upward and downward causation, while "weak emergence" would involve only upward causation.

My current position is that those metaphors of "ups and downs" are misleading, and a cause of much confusion as they contradict causal closure.

What is at stake here is the scale of observation, the scale of a map. Zooming in or out of a representation. Does nature zoom? I don't think so. Rather, there are scales of representation that are more relevant than others to understand a given phenomenon. In the case of a living being, the scale of the entire individual is relevant to understand how it self-regulates. A broader scale including the critter's immediate environment is necessary if one wants to understand the adaptative strategies mobilized by the critter.

It's in this sense that there is something people call "downward causation": large scale systems must be seen as acting in a coherent manner; you cannot cut them in pieces and pretend to understand them.

A bird that decides to fly south does so with its whole body, and usually with a whole pack of other birds too. It's a social behavior. It wouldn't make any survival sense if they all flew in different directions. There's some 'group thinking' involved. So it's not like each single feather of each single bird in the pack decided to fly south on its own account.


We are talking about emergence, when a system exhibits behaviour that cannot be inferred from the behaviour of its parts.

In this way, everything is an emergence : molecules, atoms and even particles can be considered as emergent properties of fields.

It seems so, that every system we identify in nature displays behaviour or properties that cannot be directly attributed to its corresponding sub-systems. And although each such system or sub-system is coherent there is a gap in between that no-one can explain.

It's obvious that we miss something here, something fundamental.

You say :

... causal power of the emerging shape ...

I like your way of thinking, but where is this shape? in which substance is this shape persisted? where is the interaction point (interface) with physical reality?

Perhaps, after all, everything comes out of waves, as a manifestation from another reality, beyond the physical, and what we see is only what we CAN see. Perhaps physical reality is just the behavioural aspect of things.

  • "where is this shape?" I talking of the shapes that matter takes. No shape without matter, no matter without shape.
    – Olivier5
    Nov 28, 2023 at 7:12

In the discussion above there was considerable deriding of science, the question begins with: "The concept is invoked to save physicalism from its reductionist contradictions and conjure up a physicalist world view where life can sprout out of a primordial soup, and where animals can play Beethoven's 5th."

Can anyone seriously doubt that AIs will generate "acceptable" music? Or that at least once in this vast universe a micelle and a strand of RNA or DNA came together with the right constitution to start cellular life? The contention that there are things in this universe that simply could not occur as a result of physical interactions needs much more support than a simple declaration.

The examples of weak emergence, like murmurations etc., usually miss some external factor. It is like staring in wonder at spaghetti emerging from flour and water in a factory without noticing that the mix is forced through holes.

Can anyone give an example of weak emergence that is true emergence without factors such as information processing, extra degrees of freedom for movement etc. creating the "emergent" form?

To my knowledge there is not a single case of strong emergence that is not due to missing out a dimension (ie: dots to letters) or information processing (epigenetics, behaviour) or an analysis of how alternative forms or systems might fail or due to hypersensitivity to initial conditions etc. etc.

Can anyone supply a cast iron case of strong emergence where outside factors such as dimensionality (degrees of freedom for motion) or physical interactions etc. are not involved?

Most philosophers realise that our scientific knowledge of the universe is very far from complete. 95% of the material in the universe is of unknown composition and quantum theory is unconnected to an adequate interpretation. Consciousness is not even defined adequately let alone explained. Emergence is conceivable in science but it would be subsumed under a theory of retrocausality or of entanglement in quantum physics etc. and be part of the corpus of scientific knowledge. However, as yet such phenomena are theoretical.

Trawling science for missing connections is a useful exercise for scientists because it points to the need for new theories. It is a fallacious exercise for philosophers to find a missing link and declare "emergence"!

On the subject of reductionism, philosophy seems to avoid the way that science is a description of events and relations between events. Science does not have a "physical" world that differs from the world.

  • I am all for science. What I loathe is reductionism, which is bad metaphysics.
    – Olivier5
    Nov 27, 2023 at 16:53
  • On re-reading the question, I selected a a passage above that, as you say, was not fully representative of your view. I have added a bit above to address my misgivings about the validity of the concept of reductionism. Nov 30, 2023 at 19:45

I don't believe the distinction is clear or effective. Let's accept that the difference between resultants and emergence is that the former is the literal sum of its parts and the latter isn't. The mass of a cupful of sugar is the sum of the masses of the individual granules within it, so is clearly a resultant, as is the mass of a cup of flour, a cup of milk etc. A cake baked with those ingredients clearly has some properties that none of its ingredients posses, so it is more than the mathematical sum of its parts- the cake has emerged from the process.

I assume you would agree that there are clearly different degrees of emergence. The factors that determine the difference between a cake and its ingredients are relatively few compared with the unfathomable number of factors that determine the difference between, say, the behaviour of the population of Palm Springs and the atoms forming the bodies of the poor people condemned to live there.

It seems to me, at least, facile to reduce all of that complexity to weak and strong, downward and upward, particularly when the labels on those gross pigeon-holes are so poorly defined that people can take entirely different views on what they mean.

As for Bedau and his claims about microstates etc- he is ignoring the fact that information, rather than physics alone, plays a role in the evolution of processes. Suppose I have an led screen connected to a power source and some circuits. I can apply the laws of physics to determine which diodes on the screen will be emitting photons and which will not. What physics cannot tell me is whether the resulting pattern on the screen means anything. Is it a fetching picture of my niece or a 'sell' recommendation that sparks a collapse of Western economies?

Much more clarity about the various directions and types of emergent behaviour is needed before you can hope to develop a meaningful theory of it.

  • Thank you Marco. Agreed, and like the example of the cake. :-) I have tried to bring more conceptual clarity to the question in my own answer here: philosophy.stackexchange.com/a/105645/67046 Would appreciate your comments and help on it.
    – Olivier5
    Dec 1, 2023 at 7:47

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .