OK, let's say you're looking down at a full printout of a block universe. Every physical fact for all times specified. Then let's say you do Solomonoff induction on that printout -- find the shortest program that will print it out. Then for every physical fact in your printout, you can find the nearest register in your program it was printed out of. And then you can imagine causal surgery -- what happens to your program if cosmic rays change that register at that moment in the run. That gives you a way to construe counterfactuals, from which you can get causality.

ETA: There's still some degrees of freedom in how this gets construed though. Like, what if the printout I'm compressing has all its info time-reversed -- it starts out with details about what we'd call the future, then the present, then the past. Then I'd imagine that the shortest program that'd print that out would process everything forward, store it in an accumulator, then run a reversal on that accumulator to print it out, the problem being that the registers printed out from might be downstream from where the value was. It seems like you need some extra magic to be sure of what you mean by "pretend this fact here had gone the other way"

For instance, how would an omniscient agent decide if A causes B according Eliezer's account of Pearl?

An omniscient agent would have no reason to decide if A causes B, since causality is a tool for predicting the outcomes of interventions, and the omniscient agent already knows what's going to happen. The concept of "causality" is only useful from a perspective of limited knowledge, much like probability. And the concept of an "intervention" only makes sense in a level of abstraction where free will is apparent.

Pearl addresses this in slide 47 of this lecture. Causality disappears if you consider the entire universe as your object of investigation.

For instance, how would an omniscient agent decide if A causes B according Eliezer's account of Pearl? I don't think they would be able to, except maybe in cases where they could count frequencies as a substitute for using probabilities.

Indeed. Eliezer motivates causal graphs by pointing to limitations in the observer: It's just not feasible to gather all of the necessary frequencies to do pure Bayesian conditionalization. But that's saying something about the observer, not about the object that the observer is talking about.

We're only talking about causal networks because of our own limitations as epistemic agents. It seems a weird leap to say that reality itself is made out of this stuff (causal networks) that we wouldn't even be thinking about if it weren't for our own imperfections.

It seems to me that this is the primary thing that we should be working on. If probability is subjective, and causality reduces to probability, then isn't causality subjective, i.e., a function of background knowledge?

Thanks for succinctly articulating what was bothering me about this post. Can't upvote this enough.

This question seems decision-theory complete. If you can reify causal graphs in situations where you're in no state of uncertainty, then you should be able to reify them to questions like "what is the output of this computation here" and you can properly specify a wins-at-Newcomb's-problem decision theory.

An omniscient agent could still describe a causal structure over the universe- it would simply be deterministic (which is a special case of a probabilistic causal structure). For instance, consider a being that knew all the worldlines of all particles in the universe. It could deduce a causal structure by re-describing these worldlines as a particular solution to a local differential equation. The key difference between causal vs. acausal descriptions is whether or not they are local.

Wolfram 2002 argues that spacetime may actually be a discrete causal network and writes:

The idea that space might be defined by some sort of causal network of discrete elementary quantum events arose in various forms in work by Carl von Weizsäcker (ur-theory), John Wheeler (pregeometry), David Finkelstein (spacetime code), David Bohm (topochronology) and Roger Penrose (spin networks; see page 1055).

Later, in 10.9, he discusses using graphical causal models to fit observed data using Bayes' rule. I don't know if he ever connects the two points, though.

When you make this claim about the universe's ontology, it isn't clear whether you mean the is of identity or predication. Are you saying that the things constituting the universe are parts of a connected fabric of causes and effects or that the universe is reducible to causes and effects. The first claim is a standard part of conventional materialism (Pearl's recent contributions notwithstanding). The second claim is one that's set out in Alexander Bird's recent book Nature's Metaphysics: Laws and Properties.

This is a somewhat radical program in that it proposes reducing structural properties to dispositional. Are you or aren't you proposing that (for example) squareness can be reduced to cause and effect.

Once again speaking as the author of Eliezer's Sequences and Mainstream Academia...

Like Eliezer, I haven't seen anyone suggesting that a universe is a connected fabric of causes and effects in the Pearlian sense. Nor have I seen anyone suggest that one can only meaningfully talk about things that one can find by tracing causal links.

If some young philosopher wants to publish some great, attention-grabbing papers in Nous early in their career, I suggest they write up the philosophy-paper versions of the core ideas in The Useful Idea of Truth and The Fabric of Real Things (citing Eliezer, of course).

This seems especially difficult noting that although we can claim that things are caused by certain mathematical truths, it doesn't really make sense to include them in our Bayesian net unless we could say, for example, how anything else would be different if 2+2=3.

Physicists tell us that reality is, at the lower levels, described by differential equations. Those describing the temporal evolution of systems are generally hyperbolic differential equations. That is, they have microscopic causal structure: the properties at a point (x,t+dt) depend on the properties only in a small, finite neighbourhood of x at time t. This is what allows larger scale events to be described more abstractly in terms of causal graphs. (A known problem here is the time-symmetry of all these equations. I don't have a solution to that either.)

Some have speculated about the very finest scale being discrete, with fundamental laws of temporal evolution such as those of cellular automata or graph rewriting. That would also provide the fundamental causal structure from which causal structure on the macroscopic level emerges.

A universe whose fundamental laws were all elliptic differential equations -- those in which a change in boundary conditions in one place changes the solution everywhere at once -- would not support causal reasoning. Everything depends on everything else and none of its emergent phenomena would be describable by sparse causal graphs. I'm not sure you could have agents within such a universe, for it to look like anything to them, or any notion of time, but we can imagine such universes from outside.

Does the idea that everything is made of causes and effects meaningfully constrain experience?

A causally disconnected event would not affect our experience, so no, it does not constrain our experience. But it wasn't meant to: it was meant to constrain our maps, not our experience. To stop us from believing meaningless statements.

Can you coherently say how reality might look, if our universe did not have the kind of structure that appears in a causal model?

Every causally separated group of events would essentially be its own reality.

To answer this, I need to answer another question: What would the universe look like if it did not have the structure of causal models? If I know that then I can know whether or not that universe looks different than ours.

So we're talking about a universe where there is no A --> B causal connections. Where you can't accurately say something like "When I eat, it causes me to be less hungry," or even say anything, since "saying" something requires some sort of causal ability: the ability to push air in intensional patterns.

And that universe... really doesn't look like ours. I might want to talk about a universe where there are correlations but not causations, but then how do I explain the correlations? Are they just brute facts? That seems unlikely. But even in that event, I would expect rules to break down in chaotic ways: one day, food wouldn't make me feel nourished. And it wouldn't be because I ate the wrong foods or something like that, it'd just be because the correlation broke down. And that really doesn't look like our universe either. I may be wet because it was raining, but I don't get wet merely because some 'correlation' between 'sunnyday" and "notwet" broke down.

Yes, to a limited extent I think I can.

A universe without a completely causal structure would have to have a number of effects that have no cause. (This need not apply to all effects in this universe, merely to a subset of effects). The Steady-state universe, a now abandoned alternative to the Big-bang model, may be an example; in the steady-state universe, if I remember correctly, it was theorised that small bits of matter (hydrogen molecules) appeared out of nowhere at random times, at a very low rate. This is an example of an effect without a cause.

Alternatively; consider a universe where a man suddenly appears out of nowhere in the middle of a public area. He claims to be a time traveller, from fifty years in the future, coming back in time to prevent some terrible disaster. Though his story is unbelievable, the disaster he predicts is prevented. Fifty years pass, and the time traveller is not sent back to the past (since the disaster was, after all, prevented). This does not cause a paradox (the laws of this universe are that matter can appear at any time, in any arrangement, including a person with false memories of time time travel from a non-existant future) Such a potential universe thus has an effect (the man appears) without a cause.

At first thought. It seems that if it could be falsified, then it would fail the criteria of containing all and only those hypotheses which could in principle be falsified. Kind of like a meta-reference problem; if it does constrain experience, then there are hypotheses which are not interpretable as causal graphs that constrain experience (no matter how unlikely). This is so because the sentence says "all and only those hypothesis that can be interpreted as causal graphs are falsifiable", and for it to be falsified, means verifying that there is at least one hypothesis which cannot be interpreted as a causal graph which is falsifiable. Short answer, not if we got it right this time.

(term clarification) All and only hypotheses that constrain experience are falsifiable and verifiable, for there exists a portion of experience space which if observed falsifies them, and the rest verifies them (probabilistically).

Several possible examples come to mind for a universe with no cause or effect.

First is a universe with only one thing in it, so that there's nothing for it to be causally connected to.

Second is a universe with multiple things in it that could in principle interact but due to the set-up of the universe never actually do interact. For example, a universe of rigid particles in a void where they would interact if they struck, but the distances between all particles are too great for that to occur in the lifetime of the particles.

Third, a universe in which its entities do interact, but nothing ever changes, so there are no nontrivial correlations. Perhaps count a universe of mutually repelling particles in a void, arranged in an unchanging crystalline structure.

Fourth, more loosely, is a universe in which its entities do interact and change, but the arrangement of all the things is such that only minimal correlations arise. Perhaps a universe analogous to a closed system containing a gas at thermodynamic equilibrium.

Prescinding from those, the idea that everything in our universe is made of causes and effects constrains my expectations in that there should multiple things (check) that actually interact (check) and change (check) and have nontrivial correlations (check). Other than the continuation of such things, I can't readily think of any sense in which the idea constrains my expectations for future experiences.

Does the idea that everything is made of causes and effects meaningfully constrain experience?

No. For any set of observations O1, O2, ..., O_N, you can construct an overprecise causal model that links some central cause to nodes O1, O2, ..., O_N. [That is, our causal model is: "You observed O1 because God willed it. Then you observed O2 because God willed it..."] Thus causal models can explain any set of observations. Constraining experience requires in addition some sort of Occam's Razor that prefers simpler causal models.

How about mild violations of causality?

Does the idea that everything is made of causes and effects meaningfully constrain experience? Can you coherently say how reality might look, if our universe did not have the kind of structure that appears in a causal model?

No. I literally assign prior probability zero to the statement that the universe is not made out of causes and effects, because there is causal structure in Turing machines and in all Turing-complete models of computation which could make up the Solomonoff prior. Causal structure is a very broad thing - it's just a sparse graph of interacting entities with a lattice ordering.

I can imagine a universe in which the local ordering I observe doesn't go as far forward or back as I thought, and the true everything-is-causes-and-effects structure is pushed one layer back to something completely hidden from me. I can imagine a universe in which I've falsely inferred an ordering which isn't there, and getting confused by cycles in a graph that I thought was causal. But a universe with no causality at the lowest layer - I think causality is inherent in too many things, and that after subtracting those things there's not enough option space left to make a universe out of.

There are three alternatives I can think of:

1) The universe has a joint probability distribution such that events are not independent, but so few events are independent that limiting the description to a causal one does not materially reduce the complexity of the "true" model. In this case, There would only be the joint look-up table.

2) All events are independent.

3) The universe is not well-described by the laws of probability.

The first case would make prediction pretty much impossible (since you're never dealing with the exact same set of variables twice). "Same river" and all that. No prediction more specific than "the universe persists in some way" would be true very often on average, since there are so many possible outcomes, and no reason to believe that the next joint probability for the event you care about is similar to the last one.

In the second, you could predict roughly the proportion of events based on the proportion of past events, but there would be no discernible pattern, or result of action.

In the third, I can't tell you what you're likely to observe, for obvious reasons.

I think it is a mistake to tie the question of what reality is to the particulars of the physics of our actual universe. These questions are about what it is to have an external reality, and the answers to them should be the same whether the question is asked by us in our current universe, or by some other hapless inhabitants of a universe bearing a distinct resemblance to Minecraft.

I can imagine types of existence which don't include cause and effect - geometrical patterns are an example - there are relationships, but they are not cause and effect relationships - they are purely spatial relations. I can imagine living in a universe where part of its structure was purely such spatial relationships, and not a matter of cause and effect.

Imagine a universe that is made only of ideal billiard balls eternally bouncing around on a frictionless, pocketless billiard table. Essentially the same thing as selylindi's idea of a gas in thermodynamic equilibrium. Imagine yourself observing this universe as a timeless observer, or to aid the imagination, that it's "time" dimension is correlated to our space dimension, so we see the system as an infinite frozen solid, 11 by 6 by infinity, with the balls represented by solid streaks inside that go in straight lines except where they bounce off each other or the boundary of the solid.

Now, this system internally has a timelike dimension, except without increasing or decreasing entropy. And the physics of the system are completely reversible, so we have no basis of saying which way is the "future" and which way is the "past" in this system. We can equally well say a collision at one time is "caused" by the positions of the balls one second in the "past" or one second in the "future". There is no basis for choosing a direction of causality between two events.

In our universe, our time is microscopically reversible but macroscopically irreversible, because of the fact that the universe is proceeding from a low entropy state (we call that direction the "past") to a high entropy state (the "future"). I am curious, can anyone coherently describe a universe with nothing similar to irreversible time, but with a useful notion of causation? Or with something like irreversible time, but no causation whatsoever? I have tried (for much more than five minutes!) and not succeeded , but I am still far from sure that it's impossible to do. It might be too much to ask to imagine actually being in a universe without causation or time, but perhaps we can think of how such a universe could look from the outside.

Well, my experiences could not be readily predicted by a simple Bayesian net. Thus I would expect the joint probability distribution on all things to be really complicated unless there were some other kind of pattern to it. Heck, maybe my experiences correspond to repeated independent samples from a giant multidimensional Gaussian or something (rotated of course so that the natural observable variables have non-trivial covariance).

Asserting that a particular causal model is an accurate description of the universe certainly constrains experience to fit the causal model. Asserting that it is possible to accurately describe the universe with a causal model is tautologically true because a fully connected model fits every possible probability distribution. Asserting that it is possible to accurately describe the universe with a simple causal structure constrains experience to match a simple causal model. If you know that the universe fundamentally works by running some causal model, asserting that the universe runs this particular causal model predicts that you will never find a more accurate causal model for describing the universe. I'm not sure how asserting that the universe fundamentally works by running some causal model would constrain experience.

If the universe were not governed by cause and effect, then we could not consistently improve our predictions of the future by observing the past, even by a little bit.

I suppose I would say that reality would look as if things happened with no observable pattern related to the things that happen before them, but looking at things requires a long causal chain between photons being emitted and signals in my brain. Supposing I happened to somehow flash into existence for an instant in a noncausal world, or that causality suddenly failed, I would not expect to be able to experience anything past that point since my experiences depend on so many causal processes.

I would expect not exist in a way that suggests causality, e.i. being born and then expecting death, rather than the other way around. This is hard for me to imagine because I didn't really evolve for that world. It's possible that our universe doesn't work that way at the smallest level, but it seems might suspicious that random events lead to a largest world that operates very deterministically. Still, it is possible that this is just the manifestation of probabilistic laws at the smallest level. It's definitely paying rent so far,(for those who do the experiments) so that's we're going with, and there hasn't been a good argument or experiment against it yet.

Infintesmal "violations" of causal laws as manifestations of probabilistic laws don't seem to effect me very much. Large ones that would pay rent haven't happened on the level that would pay rent on an evolutionary or personal level, and, as I understand it (which is not terribly well) these probably won't happen unless the universe ran from the big bang to heat death a couple hundred times.

I can make models in my head where the universe (on my scale) is really chaotic, but looks deterministic because of a conspiracy by matrix gods or whatever, but that seems to violate Occam's Razor, for what that's worth when matrix gods control your life.

My first answer is that the idea of 'interventions' comes from causality- if I don't like being wet, and it's raining, I can deploy an umbrella, and that will make me not get wet(ter) from the rain. The idea that everything is made of causes and effects meaningfully constrains actions, because an agent that understands causes can manipulate reality better than an agent which doesn't understand causes.

But that's just a further elaboration of what reality looks like now. It's difficult for me to imagine a world without causality- and I don't think that's just because I (like most humans) am a deeply causal thinker. Causal models are just math, and so they can be imagined just like multiple spatial geometries can be imagined, regardless of what the universe's real shape is. I think you would need to have a universe in which no causal models could be justified by the data, which would be an incredibly strange place.

And, actually, by the definition of universe you use in the post, a universe without a causal structure would just be a single node, forever alone.

Does EY give his own answer to this elsewhere?

Meditation 3: [Hardest of the meditations, for me.] Let us observe the difference between [post-utopian]-->[colonial alienation] and a connected thing (say [I see you picked Ace]-->[You see you picked Ace] from a deck of cards): In the first case, there is no way to settle an argument about whether Ellie is post-utopian or not. We would predict that it would cause arguments between people that are not settled. Anything connected to the causal web is more likely to lead to settlable arguments, at least among people behaving more-or-less rationally. It is not a perfect test, but it does suggest that I expect to see different things from connected networks and unconnected networks, like people changing their minds.

It would be completely random, with all events being equally likely at every point in time. It would have no history, since the past has no effect on the present or future

What is the difference between constraining experience and constraining expectations? Is there one?

I think that in a universe without a cause and effect structure, we'd tend to see more chaos than we do. Casual models would tend to fail to correspond to reality; all we could do is attempt to reason over joint probability distributions, which, as was explained, is kind of hopeless.

I'm having a hard time making sense of the question. I'm sort of trying to imagine that there are no causal relations, and then opening my eyes to see what's different. Except 'seeing' and 'looking' don't make sense any more. What could it mean for something to 'appear'? I can't get a grip on even the idea of 'experience'.

At which point I conclude that either I am not imaginative enough, or the exercise is inconceivable.

(Written before reading other comments.)

Can you coherently say how reality might look, if our universe did not have the kind of structure that appears in a causal model?

Assuming our universe is causal, then no you cannot. Any universe you can imagine has laws of physics which can be modelled by the interactions of the neurons in your brain, and are therefore causal.

There might be some things that can only be experienced in an acausal universe, but it is not possible for me to imagine them.

In a universe without causal structure, I would expect an intelligent agent that uses an internal causal model of the universe to never work.

Of course you can't really have an intelligent agent with an internal causal model in a universe with no causal structure, so this might seem like a vacuous claim. But it still has the consequence that

P(intelligence is possible|causal universe)>P(intelligence|acausal universe).

This one is great - it really does have the contradictory nature of traditional koans.

Just try to picture what you would do to test whether the universe was causal, and how we would adjust our models based on such a test.

My reply (before reading other replies) is that no, such theories are not forbidden. There is a causal link with the rest of the universe; neurons are causing consciousness. Consciousness, in turn, does not need to cause anything else to be part of the universe; it is part of the universe merely by being caused.

If consciousness is epiphenomenal, then what generated your question? I assume you are positing non-conscious people who ask all the same questions about consciousness that we do.

I don't see a reason to rule out neuron-generated epiphenomena a priori - for example, the most elegant explanation of the phenomena might predict some entity that cannot be measured directly, and never affects anything measurable after its generation - but if they existed, we wouldn't notice and wouldn't ask questions about them. Therefore, whatever real thing it is you're asking about cannot be an epiphenomenon.

If true consciousness is an epiphenomenon, then your question is not motivated by experiencing true consciousness. If your question is motivated by experiencing true consciousness, then true consciousness is not an epiphenomenon.

Does your rule there forbid epiphenomenalist theories of consciousness - that consciousness is caused by neurons, but doesn't affect those neurons in turn?

A forest does not cause trees, and trees do not cause a forest; they are related, but their relation is of a different kind.

However, if you're willing to abuse definitions a little bit, you can pretend that relation is causal; if you define a forest in terms of things like tree-density, then the forest is "caused by" trees, but it's a causal dead-end which affects nothing in turn. The same holds for neurons and consciousness. However, it would be silly to talk about a bunch of trees in the same place which were not a forest, and similarly silly to talk about a working, talking brain without consciousness.

You can account for a theory where neurons cause consciousness, and where consciousness has no further effects, by drawing a causal graph like

(universe)->(consciousness)

where each bracketed bit is short-hand for a possibly large number of nodes, and likewise the -> is short for a possibly large number of arrows, and then you can certainly trace forward along causal links from "you" to "consciousness", so it's meaningful. And indeed for the same reason that "the ship doesn't disappear when it crosses the horizon" is meaningful.

We reject epiphenomenal theories of consiousness because the causal model without the (consciousness) subgraph is more simpler than the one with it, and we have no evidence for the latter to overcome this prior improbability. This is of course the exact same reason why we accept that the ship still exists after it crosses the horizon.

[Cheating, since I already read some Zombie sequences, but have not read any replies in this thread] The consciousness causes you to speak of consciousness, which is the result of neurons in your brain firing your jaw muscles (and other muscles, and so on). If it was epiphenomenal enough that none would talk about it, we wouldn't have this question in the first place.

[Has consciousness] --> [Writes books/blogs on consciousness]

Causually connects consciousness to the universe.

The rule does not rule out epiphenomenalism. It only rules out entities without causal connection in any direction with the material world, and epiphenomenalism says that there is a connection, albeit only in one direction.

Epiphenomenalism is ruled out for other reasons.

Epiphenomena can be considered in terms of causal graphs. Suppose you have two causal graphs proposed to describe some phenomenon. In one, there is a variable called X, with many arrows in and out. The second graph is identical to the first, except that X is renamed to a new variable Y, then X is added back in with a causal arrow from Y to X, and no other arrows impinging on X. Y is stipulated to be unobservable and un-intervenable on, and X to be observable but un-intervenable on in both graphs.

Given these limitations on observations and interventions, is there any experiment that can distinguish between the two graphs? I think there is not.

If not, what does it mean to say that there is such a Y, and that it is Y, not X, that is producing the apparent causal effects of X? It's almost as if at the meta-level, it is Y, not X, that is the epiphenomenon.

I would say that it isn't ruled out a prior because a causal chain does run from the observable (the neurons) to consciousness.

So if Universe A features epiphenomenal consciousness, and Universe B doesn't, and that we consider the statement that we are in universe A and not universe B, then looking back at the rule:

"For a statement to be comparable to your universe, so that it can be true or alternatively false, it must talk about stuff you can find in relation to yourself by tracing out causal links."

These "causal links" you trace out are part of the map, not part of the territory - you have to be able to deduce their existence. And in this case (unlike the spaceship scenario), there is no way anybody can deduce the existence of the neuron -> consciousness link, since by definition nothing can be observed about the consciousness.

=> so, firmly in the "meaningless" camp.

A one way causal connection cannot be observed. If neurons cause consciousness, but consciousness does absolutely not affect anything else, then there is literally no way to observe consciousness, and so you must in addition to the description of the causal universe include the fact that there are things that are affected by the universe's existence but does not affect the universe, and furthermore that consciousness is one such thing.

A strictly simpler theory is that there is a causal universe, without all that epiphenomea cruft.

Also, the viewpoint of epiphenomenal consciousness is very much triggering my pattern maching of 'human specific inbuilt stupidity'.

"For a statement to be comparable to your universe, so that it can be true or alternatively false, it must talk about stuff you can find in relation to yourself by tracing out causal links."

With the above solution, then yes epiphenomenalist theories of consciousness are meaningful. They clearly describe networks in which consciousness connected to the rest of reality that you experience. On the other hand, I think that this is because the above statement fails at its intended goal rather than that these theories are actually meaningful. In particular I think one should append to the above:

"Furthermore, it must not be possible to remove this stuff (and perhaps some other stuff) from your causal network without affecting things that you can experience."

It doesn't rule it out. Unless you're directly observing those epiphenominal nodes, Occam's razor heavily decreases the likelihood of such models though, because they make the same predictions with more nodes.

(Written without reading other comments.)

The theory does not forbid a node from having no causal effect on anything else, which is what I think an epiphenomenal consciousness would be. But such a node could not be measured. A logical positivist would say this makes the theory meaningless, and I'm inclined to agree.

Conceivably, if the universe runs on a computer, there could be a node which cannot be measured from inside the universe but could be measured from outside. Perhaps debug info is turned on, and any time neurons fire in patterns that match some regex, the word "consciousness" is printed to stderr. I would not say this is meaningless; if it is true, it gives us a way of communicating with whoever is watching stderr (but no guarantee that such a being exists or would talk back).

But it is not suitable as a theory of consciousness, unless you want to stipulate that neurons write about consciousness for reasons that are completely uncorrelated to consciousness.

Impossible, no; meaningless, yes.

Consciousness in reality causes us to emit sentences about an awareness of subjective experience, so there is a coupling between neurons and the conscious algorithm being run by those neurons.

If consciousness were merely a passive awareness with no causal influence upon anything else in reality, it would not be causally entangled with the universe. This is as close to "meaningless" as I can imagine.

As I read it, the rule does not forbid epiphenomena. Epiphenomena are caused by ordinary things that we can observe, so they are connected to us by causal links, even though we can never discover these links, since epiphenomena do not themselves cause anything we can observe.

This seems like a coherent way the universe could be, but isn't. The machine simulating the universe could constantly scan it for blue objects and populate a list of all blue objects--but without using that list for anything further. This would be an epiphenomal blue-ness tag.

Drill down on "outside the universe," as it seems to conflict with the definition of universe we're using here. Presumably, we mean something which has access to the nodes in the connected fabric of causes and effects, but is not an input to any of them- much like the proposed consciousness. If consciousness is caused by neurons, it's in the fabric, and our omniscient observer will be able to see whether or not consciousness is a node in the fabric or not. We'll avoid the infinite regress by enforcing that all observers are inside the universe / the connected causal fabric, but they are differentiated by where they are in the fabric.

From inside the fabric, we can only comment confidently on the nodes we have access to, and implicitly the nodes which are ancestors of those nodes. Agents like us are both causal ancestors and descendents of each other- we see clear feedback loops that convince everyone of the reality of other agents (barring those confused by solipsism, of course). There could be silent observers (of the consciousness variety or otherwise) that are descendents but not ancestors of the nodes we have access to- and because they're not ancestors of the nodes we have access to, we can't comment confidently on them! But by Occam's Razor, it's generally better to not put such nodes into your model of the universe, since they don't give you any additional predictive or manipulative power, but still cost cognitive resources to lug around.

(It seems to me that a principle that only relies only on the structure of the causal graph which excludes silent observers will also exclude the spaceship that has passed the horizon- and so either we need a principle from outside the model, like "my intuition says spaceships don't disappear but silent observers aren't real," or to put them in the same bin.)

"We can imagine any number of universes, that does not always lead to a good argument. In this case, the main issue with the argument is that while we can imagine that universe, it doesn't look like ours. There's no talk of consciousness, there's no self-reflection. Those are things in reality clearly caused by a link between our thoughts and our brains, one that goes in both directions.

Imagining a world in which people act exactly like people do now, but without a consciousness, strays so clearly outside the bounds of Occam's Razor that there doesn't seem to be any point in thinking about it. Adding in a mysterious 'zombie master' to make the zombies act as though they had consciousness... Well at this point, we're not talking about anything remotely resembling reality. This entire thought experiment in no way gives us any truths about reality whatsoever. It is completely meaningless."

A strict reading of the rule suggests that it doesn't; consciousness is caused by neurons, and we observe neurons.

For any precise definition of consciousness that fits epiphenomenalism, it would be meaningful. However, to my knowledge, no such precise definition has been put forward.

Well, my first thought was that it doesn't rule epiphenomenal consciousness out. It's strange that people would still talk about consciousness without it, but you can posit that people are just programmed to talk about consciousness for some reason (it's at least conceivable).

Then I looked at the next guy's answer (asparisi) and thought he had a point: Does our theory of causal links allow for causes to have probabilistic effects? (It's different to say that 'human brains sometimes cause consciousness than to say 'human brains can cause ANYTHING, like a blue goblin appearing in front of you or the universe being destroyed and replaced with another one') I'm not sure. If it does, then epiphenomena-that-sometimes-don't-happen are okay. If not, they aren't.

THEN I thought, but if consciousness is an epiphenomenon then what's strange is that people talk about it at all -- by definition, we cannot be aware of an epiphenomenon. But there could be another cause for the discussion of something we can't interact with in any way. After all, people's talk about gods is not caused by gods. There are other reasons to rule epiphenomena out, but a world with P-zombies is at least conceivable, even if it requires a lot of unlikely assumptions.

I'm not sure. And am not sure how you would you do an experiment to check. My rules aren't data typed into a computer program on which the universe runs, they're descriptions of the universe as experienced through my senses and processed through my mind be things like "inference" and colored by things like the "expectation of beauty", and "Occam's Razor."

The reason I don't believe in the epiphenomenal theory of consciousness is because of the evidence against it, starting with my awareness, the existence of all this talk about awareness, and ending with fuzzier sort of thinking like, "Animals seem awake and aware and aware that they're aware."

Oh, that and saying that consciousness doesn't cause anything you can sense seem a violation of Occam's Razor, while consciousness not effecting anything, ever, even in principle, seems to be a rejection of causality itself.

My reply, before reading other replies, is that the question is wrongly posed. The described phenomena can be part of a causal universe, because they are causal processes.

Consider the psychic cousin. I draw a card from his deck - it is (say) the three of clubs. Let us further assume that he correctly guesses the card that I have drawn, and does so in 99% of trials. In such circumstances, his statement of the card that I have drawn ('you have drawn the three of clubs!') is caused by my drawing the three of clubs. The mechanism of that causality may not be known, but it is there.

Similarly for the example of "communing on a deep level with the entire universe in order to realize that your partner truly loves you" - there's a causal link, there, and the cause is "your partner truly loves you". (Personally, I'd prefer to check the conclusion by some other means in order to prevent observer bias effects, but this becomes tricky for this example).

Purely spiritual phenomena, therefore, are firmly inside the realm of causal processes, even if they are not yet fully understood.

"Magic" just means "I don't know how it works." (Pratchett, somewhere in the Tiffany Aching novels.)

If the world is exhibiting some regularity, you can always ask how that happens. "No mechanism" is itself a prediction: that none will be found. Where did that prediction come from?

Causal diagrams don't require understanding of the links- if the content of the card influences your cousin's claim, then we would draw an arc from the card to the claim in our causal diagram, even if we don't know how he's influenced by the card.

(Privately, I would suspect the speaker's belief is not rigorous, and would not put much weight by it, but why challenge them on a factual matter when we're discussing causal networks?)

It's not clear to me that you've sufficiently expanded your belief that your partner truly loves you, or what it means to commune with the universe, or what separates physical and non-physical processes. If we define as real things which are part of reality, and acknowledge that your belief in your partner's true love exists in reality, why are we not content to find real causes for that belief?

(Of course, there are many status reasons to turn to spiritual causes. But the instrumental benefits are probably outweighed by the epistemic detriments- or, at least, I should not privately believe their claim, even if I consider it worthy of public endorsement.)

Taboo the word real for a moment. Also any related words, like 'actual.' What do you mean when you say that it can be real?

You say your cousin can tell you the name of a card before he looks at it, after a random draw of the deck. But he does it. It's an act on his part. This isn't a mere word-issue either: you don't think the same thing will happen if I try to predict a card you draw from a deck. So you are talking about a direct link between his statement and the card. Unless you think he is doing it by chance (so that there is just a correlation, and an extremely improbable one at that) you think that there is a causal link between the card drawn and the prediction. Saying you don't know what it is, is not the same thing as saying that it is not there.

Likewise, when you say that you commune with the universe, you are stating some act, "communing" and some result "finding out that your partner loves you." You don't expect this to fail the next time you do it, or you wouldn't perform the act to that effect. (You might perform it to "see if it works this time" but that would be another matter.) So I don't think you really believe what you think you believe. Why would you "commune with the universe" if it did not cause effects such as "realizing your partner truly loves you"?

I am interested in the idea that what your cousin does happens without a mechanism. Does this mean that the process does not involve your cousin at all? That it happens whether or not your cousin is around? If so, why do you say that it's your cousin who does it?

I could ask the same kind of questions about your communing with the universe, but let's take these things one at a time.

I agree that anything else is outside the realm of science, but it can still be real, you know. [Two examples with hidden mechanisms]

Mechanisms can be well hidden; if you deny that there is mechanism, you're just cheating yourself out of the chance to figure out what the mechanism was. When you "commune with the universe", you're actually putting your brain into a meditative state where it queries large volumes of remembered weak evidence that you can't recall by normal means. You can use that state for other things, too (but you'll fool yourself if you don't understand its limitations). When your cousin does card tricks, he's explicitly presenting you with a hard puzzle - figure out just how he's cheating. Answers are in books, but custom forbids giving spoilers. Figure it out, and you can fool others the same way.

If your cousin reliably names my card, it is causally correlated to my drawing the card. I never specified the nature of the casual relationship-whether it's mirrors, marked cards, or the cards whispering in his brain, you told me that my action and his statement are connected. If 'purely spiritual phenomena' have effects, they're causal processes, connected at the very least to your state of mind- if they don't have effects I'm not sure what we're arguing about.

Okay, hypothetical mystic dude.

You said: "IF you draw a card... [then] he can tell you the name of your card". Sounds causal to me! Otherwise he could tell me the name of my card whether I draw it or not!

Also, you commune with the universe TO realize that your partner loves you. If you don't believe the results of your divination are caused by your partner's love why are you doing it?

In short, you may believe you believe that these are 'non-causal processes', but on the level that determines your behavior, you believe they are causal processes. I suspect this is because either labeling these things non-scientific is important to you for some reason (love of mystery, or perhaps it's what your peer group says to believe) or you don't understand what the words 'non-causal process' mean and it's just a password.

How would you reply?

Probably I would start with "You say about your cousin that it's not something that scientists could study. That's an interesting claim. Suppose I tried to study it... say, suppose I asked him to demonstrate this ability a hundred times, and wrote down for each demonstration what card I drew, and what card he named. That's one way to start to do science, to observe the phenomenon and record my observations. Would something prevent me from doing that? Would the ability itself stop working? Something else?"

Their answer would give me more of a sense of what I was dealing with. It doesn't engage with the reality question directly, but how I engage with the reality question will depend a lot on their answer to this question.

Replying without reading any of the other answers. Apologies in advance for redundancy:

Meditation 1: The psychic cousin is indeed connected to the network of things. Let's assume that it works, for simplicity, on decks of two cards: an Ace and a King.

Probabilities: Moshe picked Ace/Cousin says Moshe picked Ace -- 0.4 Moshe picked King/Cousin says Moshe picked Ace -- 0.1 Moshe picked Ace/Cousin says Moshe picked King -- 0.1 Moshe picked King/Cousin says Moshe picked Ace -- 0.4

The True Love/Communing is more complicated: Does True Love have any discernible effect? If we assume True Love, say, changes the probability of having a fight (or some property of the fight -- for example, a fight without reconciliation inside of 24 hours), then we should have a diagram:

True Love --> Communing says True Love | | \/ No fight

and resulting joint probability distributions. Since "fighting" is something observable (by a trained psychologist, say, who puts them in the "Love Lab" http://www.gottman.com/49847/The-Love-Lab.html) we have connectedness.

My cousin is psychic - if you draw a card from his deck of cards, he can tell you the name of your card before he >looks at it. There's no mechanism for it - it's not a causal thing that scientists could study - he just does it.

I believe that your cousin can, under the right circumstances, reliably guess which card you picked. There are all sorts of card tricks that let one do exactly that if the setup is right. But I confidently predict that his guess is not causally separated from the choice of card.

To turn this into a concrete empirical prediction: Suppose that I have your cousin repeat his trick several times (say 100) for me, and each time I eliminate any causal interaction between the the deck and your cousin that I can think of. Then I predict with probability ~1 that, within several rounds, your cousin will not be able to guess which card I draw.

If this prediction turns out to be wrong, and your cousin can still reliably guess which card I drew even when we are in lead boxes on opposite sides of the planet, then I will gladly discard my model of reality, since it will have predicted a true state of affairs to be impossible.

Even this wouldn't be enough to prove your cousin's power is acausal, since there are conceivable causal influences that I couldn't eliminate easily.For example, maybe we live in a computer simulation that runs standard physics all the time, except for a high-level override which configures your cousin's visual cortex to a see a picture of every card that anyone draws from a deck. But I would certainly require evidence at least that strong before even considering the possibility that your cousin can guess cards acausally.

it's not a causal thing that scientists could study

A scientist is just a person who learns about things by looking at them (ie causally interacting with them), plus some social conventions to make up for human fallibility. Do you claim that the social conventions of science stop one from learning about this thing by looking at it, or that one cannot learn about this thing by looking at it at all. If the former, then again I confidently predict that you are wrong. If the latter, then I can only ask how you learned about the thing, if not by looking at it.

Same thing when I commune on a deep level with the entire universe in order to realize that my partner truly loves >me.

You mean to say that your confidence that your partner loves you is not a result of your direct interactions with em? How terrible!

There may or may not be intervening steps, but if your cousins predictions are accurate we can create causal models that either have predictions->card drawn or card drawn->predictions.

1: If your cousin can demonstrate that ability using somebody else's deck, under experimental conditions that I specify and he is not aware of ahead of time, I will give him a thousand dollars.

2: In the counter-factual case where he accomplishes this, that does not mean that his ability is outside the realm of science (well, probably it means the experiment was flawed, but we'll assume otherwise). There have been a wide range of inexplicable phenomena which are now understood by science. If your cousin's psychic powers are real, then science can study them, and break down the black box to find out what's inside. There are certainly causal arrows there, in any case. If there weren't, we wouldn't know about it.

3: If your strongest evidence that your partner loves you is psychic intuition, you should definitely get a prenup.

CCC and others have given most of my answer. As a practical matter, I would ask: 'Do you need to commune with the entire universe in order to realize your partner loves you? If you have no good evidence taken from your relationship, from the interactions between you, that seems like a giant warning sign.'

Note too that the part about the psychic cousin (if we falsely assume that it has a clear meaning which the character wants to state openly) seems meant to describe a graph with a "spiritual" node that connects to the cousin's card-naming behavior and to nothing else that we can observe. Which does not violate this particular rule, but does seem needlessly complicated.

Mechanism is beside the point. Mechanism is just causal nodes in between. Having no mechanism just means there is a direct connection.

(Written without reading other comments.)

Let us stipulate that your cousin is indeed psychic. This is not a purely spiritual phenomenon. Then there is certainly correlation between me drawing QH and between him saying "queen of hearts". Probably no direct causal link - I'd guess it has intermediate nodes related to patterns of neurons in his brain - but the graph certainly has a path between the two nodes.

If something does not correlate with anything, then it is not real in the sense that it does not determine your experiences.

Both cases are quite different. In the first case we have an observation. The cousin can know the name of a card without looking at the card. The observer has no explanation about how the cousin knows. The observer therefore reasons says that cousin has a property P that causes him to know the card.

The moment you call P "being psychic" you add a lot of connotations that have nothing to do with what the observer knows about the process. That added baggage is meaningless.

Case two is about metaphors. The observer engages into an acitivity A to get goal B. Goal B is about having a change in his own belief system that the oberver now believes C. C being that the partner loves her. So the person assumes that there's a clear causal relationship between A and B. Some form of meditation could feel like the observer engages in A and allow him to reach B. There are two struggles: Firstly, the semantics of naming A. Naming A can plausibly help with doing A successfully. Members of this community will probably more comfortable with naming A differently. Secondly there the issue of whether a belief change in my own mind can be "real". That category of claims didn't get yet discussed in this sequence, but I think it makes sense to speak of belief changes as real.

There another issue about this koan. If you ask a buddhist whether they belief that the universe is a connected fabric of causes and effects, they'll answer: "Of course I believe in karma". You don't need to believe in a reductionist worldview to say that the world is made up of cause and effect.

As someone with some experience dealing with this, having learned how difficult it is to fix I would reply something like "You are wrong. If you want to learn WHY you're wrong, tell me and we can work on this together. Otherwise, I'm going to go now."

Playing the game a bit: "Okay, bear with me a moment, this is going to sound a little odd.

I'm not sure what you mean by "outside the realm of causal processes". Does that mean it happens on its own, with no outside influence at all? Nothing causes it, it just... Happens? Even if it's a 'magic' skill, shouldn't he be the one to activate it? I mean, worst case scenario, it's caused by someone drawing a card from a deck. It doesn't happen completely independently of reality, it's CAUSED by something. If your cousin is the only one with this power, I'm sure he could be studied by the scientists and they could figure out what lights up in his brain as he does it.

A minor note, I was once a card magician, and there are very specific ways to either force people to choose the card you want, or to figure out what card they've chosen. I can show you a few, if you want.

Next, 'communing with the entire universe' is a pretty arrogant thing to say, isn't it? I never got any communication, anyway. Question for you - how would it feel to look deeply inwards, ask 'the universe' questions, and receive answers from your own mind? Would it feel much different from what you feel now? Usually it's better to assume that confusing or 'unexplained' things are happening in your mind, not in reality. You FEEL like the universe has told you that he loves you, but that would look exactly the same as if it was just your unconscious mind telling you. How often have people said that they were deeply, permanently in love, but then it didn't work out? Do you really think you're that much better than everyone else?"

In reality, I would deny the statement about what can be don by his cousin. But for the purpose of this exercise, I would say that if there was truly no causal mechanism, you would have no basis for saying that it was true, because you would have no evidence for it. In fact, you wouldn't even be aware of it. If your cousin can name my card, he does so through a causal mechanism of some kind.

Well first of all, we're not perfect philosophers of perfect emptiness. We get our beliefs from somewhere. So it's true that all sorts of things are true that we have no evidence of. For instance, it's very, very likely there's life outside our solar system, but I don't have any evidence of it, so I act as if it's not true because in my model of the universe, it's very unlikely that that life will affect me during my natural lifetime.

I would even go far as to say that there may be matter beyond the horizon of the matter that expanded after the big bang, or that we're all running on an alien matrix, or that God is real but he's just hiding, and I act as if it's false. Not because they're untrue, or unlikely to be true, as I have no way to tell. But because I am very, very unlikely to ever, ever get evidence about any of those things, and they probably will never, and probably could never (especially in the near future) affect me. Not so much a "Nuh uh," as a "So what?"

You know your partner loves you based on evidence. If you have no evidence (from past experience or otherwise), then you are very likely wrong. Love operates according to mechanisms, and we understand some of those mechanisms.

Similarly, just because you don't understand the mechanism by which your psychic cousin works, doesn't mean there isn't one. He could be getting unbelievably lucky, or he could be playing a trick, or there could be things we don't know yet that really truly give him psychic powers. You don't know what the mechanism is, but you haven't really investigated either, have you? Even if you never find out what the mechanism is, how much evidence is that that there is no mechanism?

Lastly, I'm not sure, "no mechanism" even makes sense. What does it mean for something to have no mechanism? What does a thing that doesn't have a mechanism look like? How would you tell?

So, from the top: A Priori, Making Beliefs Pay Rent, No One Knows What Science Doesn't Know, What is Evidence?, Fragility of Value (Why something is unlikely to be true without evidence of it), Uh what was that one about you failing the art and not the other way around?, and Not Even Wrong.

How would you reply?

In real life?
"You're a loony."
::walks away::

I suspect that's not the answer you're looking for, though. ;)

Wanna play Peek-a-boo?

False, I have never observed that objects don't spontaneously vanish when they're out of my range.

A convenient implication of the "things past the Cosmological Horizon don't exist anymore" belief occurs to me. All it takes to utterly annihilate any enemy you have is a fast ship. Fly as fast as you can away from them and poof, you've caused them to cease to exist! The "Ignore Them And They Will Go Away For Real" doomsday device.

You have observed that objects tend conserve energy. You have also observed that the cosmological horizon isn't absolute, but is in fact centered on you. You have also observed that time is symmetric (charge and parity flipped). You have observed that a model of the universe without any absolute coordinates is more likely. Thus we induce that were you put on a spaceship, you would never cross the cosmological horizon, from your own point of view. Similarly it is very likely that some other person would have the same experiences.

Q. E. D(?)