Why I Reject the Correspondence Theory of Truth

I think I may be a little confused about your exact reason to reject the correspondence theory of truth. From my reading, it seems to me that you reject it because it cannot justify any truth claim, since any attempt to do so is simply comparing one model to another - since we have no unmediated access to 'reality'. Instead, you seem to claim that pragmatism is more justified when claiming that something is true, using something along the lines of "it's true if it works in helping me achieve my goals".

There are two things that confuse me: 1) I don't see why the inability to justify a truth statement based on the correspondence theory would cause you to reject that theory as a valid definition of truth. In your post, you seem to accept that there IS a world which exists independently of us, in some way or other. If I say, "I believe that 'this snow is white' is true, which is to say, I believe that there exists a reality independent from my model of it where such objects in some way exist and are behaving in a manner corresponding to my statement"... That is what I understand by the correspondence theory of truth, so even if I cannot ever prove it (this could all be hallucinations for all I know), it still is a meaningful statement, surely? At least philosophically speaking? To me, there is a difference between 'if the statement that snow is white is true, it is because I am successful in my actions if I act as if snow is white' and 'if the statement that snow is white is true, it is because there exists an actual reality (which I have no unmediated access to), independent of my thoughts and senses, which has corresponding objects acting in corresponding ways to the statement, which somehow affect my observations'. When people argue about what truth really means, I don't see how it is only meaningful to advocate for the former definition over the latter, even if the latter is admittedly not particularly useful in a non-philosophical way. 2) Isn't acting on the world to achieve your goals a type of experiment, establishing correspondence between one model (if I do this, I will achieve my goal) and another model (my model of reality as relayed by the success or failure of my actions)? I don't see how, just because there is a goal other than finding out about an underlying reality, it would be any more correct or meaningful to say that this experiment reveals more truth than experiments whose only goal is to try to get the least mediated view of reality possible.

As far as I can see, if we assume even the smallest probability that our actions (whether they be pragmatic-goal-achieving or pure observation) are affected by some underlying, unmediated reality which we have no direct access to, then the more such actions we take, the more is revealed about this thing which actually affects our model.

Huh, I did not realize how close our views are. Thank you for posting this. Did you have problems reading the Sequences where the Correspondence Dualism (reality vs models) is implicit and relied upon?

I would add a couple of points.

One is AIXI-like: the "naive" Correspondence Theory of Truth presumes (an?) external reality which we strive to understand and therefore affect, like a perturbation theory. Sort of like in Special Relativity we postulate that the spacetime is flat and unchanging. However, in many situations "reality" is determined by how we model it, like the market sentiment determines market behavior, what Eliezer called the anti-inductive property. This reminds me of General Relativity (or at least its Initial Value formulation), where there is no spacetime until you build it out of matter. Sometimes, when the interaction between spacetime and matter is weak, you can use the background calculations, such as the parametric post-Newtonian expansion, or Quantum Field Theory on a curved spacetime background. But this approach breaks down when the interactions are strong and the perturbations do not converge, resulting in non-nonsensical results, such as the Hawking radiation blowing up at the black hole horizon. But, as long as you stay away from the highly nonlinear cases, it makes sense to use the concept of External Reality and the Correspondence Theory of Truth.

Another is the question "what are you predicting, if there is no reality?" Where do the inputs you use to build your models and estimate their success come from? You call it

a brute, basic constraint on effective action.

But this is just a poetic way of saying the same thing: there are stimuli coming from outside of our hierarchy of models, at least down at the bottom level. These are definitely affected by our actions, which are mostly interactions within the hierarchy of models, but at some point leak outside of it and steer future stimuli in the desired direction (if the model hierarchy is successful in its goals). So, either you assume this invisible feedback loop and call it reality, or you bite another bullet and assume that there are models all the way down. Given that we have not yet found any barrier to building our hierarchy of models, I tend toward the latter, but I am not super-convinced that this is a better meta-model than the former.

Your position seems to entail that comparing one model of the world with another cannot produce a model that corresponds to reality. I don't see why that should be the case. If you have a transitive correspondence relationship of the form R => M(R) => M'(M) with R standing for reality and M, M' for models, that may well establish a limit on the accuracy of M'(R) but it doesn't make it impossible. Indeed if it did there could be no pragmatic basis for a model since you could never expect your model to correspond with reality in any context.

Moreover I don't think your characterization of sense data in the visual field as a "visual model" is warranted. Sense data is primitve, which is to say yellow is nothing but yellow. It models nothing else. The relationships between posited to exist between different bits of yellow, red, orange etc. and the postulated range of possible changes those relationships could undergo constitute the model. If there were no such thing as primitive sense data, then what could the relation between the position of the corner of a square and its center be but a relation between yet more relations? How would you be able to form any models at all without becoming trapped in an infinitely descending hierarchy?

If the deliverances of my scientific models match up with the deliverances of my perceptual models perfectly, I can say they are true. But there is something very unsatisfactory about this stance. The world has just disappeared. Truth, if it is anything at all, involves both our models and the world. However, the world doesn't feature in the coherence conception of truth. I could be floating in a void, hallucinating various models that happen to cohere with one another perfectly, and I would have attained the truth. That can't be right.

You don't have to subscribe to the idea that coherence is truth if you just treat this as a description of how human beings practically function. The world goes nowhere, nothing is true just because a coherent model exists that shows it to be true. We just assume it does in the absence of better evidence (or the absence of any need for a better model). All we've done is removed the ability to know that we know something, the ability to know it remains intact. In other words, M'(R) may hold even if we can't know that M(R) does, and hence know that M'(R) does.

You can meaningfully say "That's a good representation" or "That's a bad representation". There is no analog with causation. There's no sense in which some particular putatively causal relation ends up being a "bad" causal relation.

Again I perceive an insistence on knowing that you know something which is in my view unwarranted. To know anything at all, by such reasoning, you have to know it, and know that you know it, and know that you know that you know it, ad infinitum.

The correspondence theory of truth, however, describes truth as a correspondence relation between a model and the world itself. Not another model of the world, the world. And that, I contend, is impossible. We do not have direct access to the world.

What do you mean by "direct access to the world"? It seems natural to describe looking at something in the world as "access", reading of world's state, communicating information about its state to my mind. Just as information can be read from a hard drive and communicated to the state of a register in a CPU, similarly it can be read from the state of a tree outside my window and communicated to the state of my brain, or that of a camera taking a photo.

We may form a model of correspondence between the state of the tree and the state of a camera (between the tree and its photo). Such correspondence may result from camera's observation of the tree, the act of accessing the tree, that communicated information about the tree into the form of state of the camera. The model that describes the correspondence between the tree and the camera is not the same thing as the photo itself, perhaps a person may form that model.

The same situation occurs when instead of a photo in a camera there is knowledge in a mind. I may consider whether your knowledge of a tree corresponds to the tree. Or I may consider whether my own knowledge of a tree corresponds to the tree. The two models, the model of the tree and the model of the first model's correspondence to the tree, don't need to be represented by the same mind, but nothing changes when they are.

We may then further consider whether the second model (of the correspondence between the photo and the tree) corresponds to the actual correspondence between them, by considering how it formed in the mind etc. This third model may also be located in someone else's mind. For example, I may have looked at a photo and thought that it's accurate, but you may consider my judgement of photo's accuracy and decide that the judgement is wrong, that the photo does not represent what I thought it represented, that instead it represents something else.

There are just these strange artifacts of knowledge in people's heads that may be understood as relating all kinds of things in the world, including representations of knowledge, and the act of understanding them as relating things constitutes production of another artifact of that kind. Given that the parts of the world that hold these artifacts are in principle understood very well (building blocks like atoms etc.), pragmatically it doesn't matter whether "models are fundamental" or "reality is fundamental", in the sense that the structure of how representations of knowledge relate to things in the world (including other representations of knowledge) would be the same even if all mentions of reality are rewritten in a different language.

My only objection is to your use of the word "we". Who is this "we"?

I exist; and my models of other minds exist; but I never have direct, unmediated access to another mind. What would it even mean to say that there are 'other people', as opposed to models of other people inside my mind? How could I possibly be justified in thinking there are any experiences had by someone, that aren't had by me? Or any models employed by agents, other than the models I myself am employing?

The "Correspondence Can't Be Causal" section was unconvincing. The Ptolemaic model made advance predictions about astronomy that were experimentally falsified, leading to general acceptance of the Copernican system a millennium later. Models correspond to reality when the predictions they make are experimentally verified.

Regarding multi-model pragmatism, I get the feeling that you are not really arguing in the spirit of the original request for steel-manning. Due to my physics- and chemistry-laboratory training I have direct personally observed evidence that quantum mechanics and Einsteinium relativity are better descriptions of reality -- correspond more accurately -- than Newtonian mechanics and Galilean relativity. Yet I pragmatically choose to use classical models on a day to day basis. Because if one model corresponds better than another, it does not replace the old model. The old model still corresponds with reality, just perhaps not as precisely as once thought. The decision of what model to choose when making predictions depends on how accurately those models reflect reality within the problem domain, how efficient the model is to compute, and how much error can be tolerated. Pragmatism and correspondence are related but different issues.

The correspondence theory of truth is mainly a claim about what truth means....not about what you should use. There are various arguments to the effect that you can't confirm correspondence,but that doesn't directly affect the semantic argument. The inaccessibility of correspondence would mean there is no justification for correspondence truth, but truth can exist without justification.

Pragmatism, similarly, is the claim that truth is... means...usefulness. It's not a claim about reality.

Ultimately, it seems to me the only clear criterion the correspondence theorist can establish for correlating the model with the world is actual empirical success.

Again, the correspondence theorist could have reasons to think that truth is correspondence, whilst still using success as a justificational criterion.

But I don’t think this maneuver can save the correspondence theory. The correspondence theory bases truth on a representational relationship between models/beliefs and the world. A model is true if it accurately represents its domain. Representation is a normative relationship. Causation is not

Causation can be. A causal relation isn't necessarily normative, for some version of normativity, but it could be...but it takes extra information to determine that it is. This can easily be seen from computing: computers can perform normatively correct computations, but can have bugs.

Always glad to see pragmatism represented on LW. I feel like rationalist types instinctively lean towards a correspondence theory of truth, but I feel like as a group, they are actually (or at least, could be) more sympathetic to the pragmatist view of truth than they realized.

This post follows pretty closely the argument I was going to make in a LW-targeted defence of pragmatism of my own which I had been half-heartedly planning to post for a long time. Thanks for doing a good job of it.

Representation is a normative relationship. Causation is not. What I mean by this is that representation has correctness conditions. You can meaningfully say "That's a good representation" or "That's a bad representation". There is no analog with causation. There's no sense in which some particular putatively causal relation ends up being a "bad" causal relation.

This is an important point, and if I agreed, I think I would join you in rejecting the correspondence theory of truth. (In my case, I'd just go to quietism - a polite refusal to have a "theory of truth" beyond Tarski's formula - rather than pragmatism.)

But here's the thing. There can be a bad causal relation, with semantic significance. If "horse" utterances are sometimes caused by cows, but usually by horses, and the cow-to-"horse" causation relation is asymmetrically dependent on the horse-to-"horse" causation relation, then the cow-to-"horse" causal route is a bad one. The asymmetric dependence is a sign that "horse" means horse, and not cow. (H/t Jerry Fodor.)

My comment in the other thread

If this were true we ought to be blind to what is not of potential use to us. We are also sometimes unclear on what we want but our understanding doesn't collapse under it's own weight in this situation.

Pure sense data could argued to be model free. Sense data is also the model that is simultanoeusly in territority. Therefore anything that is coherent with sense data has atleast something to do with the actual world. Now given we don't usually process it as such but make goal-oriented low-level representations. But also if we did not any level to fall back on when our needs change we would be held prisoner by our early needs as it would be impossible to see the world as anything else.

This reads like the more correct title would be "Why I Reject Correspondence Theory Of Utility". You could argue that we don't test beliefs for truth but for utility but all that could achieve is to say that the seeking a theory of truth is useless.

I've got feeling that the implicit LessWrong'ish rationalist theory of truth is, in fact, some kind of epistemic (Bayesian) pragmatism, i.e. "true is that what is knowable using probability theory". May also throw in "..for a perfect computational agent".

My speculation is that the declared LW's sympathy towards the correspondence theory of truth stems from political / social reasons. We don't want to be confused with the uncritically thinking masses - the apologists of homoeopathy or astrology justifying their views by "yeah, I don't know how it works either, but it's useful!"; the middle-school teachers who are ready to threat scientific results as epistemological equals of their favourite theories coming from folk-psychology, religious dogmas, or "common sense knowledge", because, you known, "they all are true in some sense". Pragmatic theories of truth are dangerous if they come into the wrong hands.