The End of Cartesian Demons
Tuesday, August 9, 2011
Follow up to: Meaningfully True
In “The Origin of Truth”, I talked about how knowledge is rooted in the interpretation of experiences, such as sensory perceptions, aided by language, imagination, and logic.
In “Meaningfully True”, I elaborated by defining what it means for something to be true or false. In particular, meaningful statements are those statements which say that certain experiences will occur and certain experiences will not occur, the true statements are those where the experiences which must occur do occur and the experiences which must not occur do not.
So armed with an idea of what knowledge is, I now set out to venture into addressing some of the common philosophical problems and thought experiments regarding knowledge: the possibility of Cartesian Demons, the possibility of living in the Matrix, the possibility of Solipsism, and whether or not there is an external reality.
Of course, I also explain what these problems are, so if you’re already freaking out trying to remember what you may have learned in Philosophy 101, have no fear — I’ll hold your hand throughout this essay. You may even learn something cool.
The Cartesian Demon Under Your Bed
When a philosophical discussion comes to knowledge, the conversation almost always turns to the question of “How do you know all your experiences aren’t just some elaborate deception?” This question is also typically associated with a very common hypothetical scenario: the Cartesian Demon. In 1641, philosopher René Descartes wrote “Meditations on First Philosophy” in which he hypothesized the idea of an evil demon who is “as clever and deceitful as he is powerful” and “who has directed his entire effort to misleading me”.
In this scenario, there would be an external reality but it would be radically different than anything you know, because all your experiences would instead be fed to you by this cunning demon, who has tricked you into thinking you’re in an entirely different reality than you’re in now. Therefore the “How do you know all your experiences aren’t just some elaborate deception?” takes the form of “How do you know you’re not being deceived by a Cartesian Demon right now?”
The answer from the theory of knowledge I outlined in “The Origin of Truth” and “Meaningfully True” is rather unique and kind of stunning: it doesn’t matter.
It doesn’t matter? What do I mean? How could the idea that we could be utterly deceived about reality possibly not matter? In “Meaningfully True” I outlined four different ways we can know what is true — we can make predictions and test them, we can come up with goals and accomplish them, we can check all our beliefs for coherence, and we can use multiple methods and see if they come to the same belief. Most importantly, outside those four techniques, there is nothing we can do to see if something is true.
So given that, consider a Cartesian Demon that manipulates your sensory inputs so that whenever you hold certain beliefs, your predictions will come true, your goals will be satisfied, your beliefs will cohere, and your methods will cohere. This means that as far as we possibly can be concerned, the beliefs the Demon manipulated us into believing are beliefs that are true.
Even if you are influenced by a Cartesian Demon, you still will collect knowledge from experiences that you can use to satisfy your goals, and you still will be able to make predictions from the experiences you get and see if they come true. The methods of knowledge are no different if they come to you from an external reality than if they came to you from a Cartesian Demon.
The Difference in the Demons
Still confused? Consider this: name one difference between a world with a Cartesian Demon tricking you and a world without that Demon. There’s one catch though — that difference has to be something you could possibly/potentially know about, even if only in principle. This rules out knowing of the Demon itself, since the Demon will always trick you into not knowing the Demon.
If you’ve come up with absolutely no difference, then congratulations — there is absolutely no difference between a world with a Demon and without that you could possibly care about. Even if such a Demon existed, you would still go on exactly as before; your experiences being no less meaningful and no less worth acting upon.
Since something with no differences is the same, therefore these worlds (with a Demon and without) are, for all purposes we could possibly care about, identical.
Testable in Principle and in Practice
To make this even more clear, let me explain exactly what it means for something to be testable in principle and how this differs from something being testable in practice: Something testable in principle is something that is capable of being tested provided we had unlimited resources. Something testable in practice is something that can be tested with the resources we have. Testing is doing something to specifically see if an anticipated experience becomes an actual experience.
Consider the idea that the Earth is round, an idea with an interesting history. This is a meaningful idea, because it anticipates many experiences — the Earth will project round shadows on things like moons, it will be possible to go forward and eventually return to where you started, geometry will work a certain and consistent way, gravitation will work a certain and consistent way, and looking back at the Earth from space will reveal a ball-shaped object.
We’ve tested all those things, revealing a round Earth. Those anticipated experiences were testable in practice, and still are. However, large swaths of those experiences were once not testable in practice — those living in the time of the Egyptians certainly had no means to look at the Earth from space, let alone circumnavigate it. Those things were testable in principle, but not in practice. Though the Egyptians probably could have done some of the geometric verifications if they were dedicated; those were testable in practice, though not actually tested.
The Matrix and Other Cartesian-Like Hypotheses
What of other problems that involve our inability to be certain we are in a “real world”. How do we know we aren’t in The Matrix? How do we know we aren’t dreaming? How do we know that we aren’t a brain in a vat? How do we know the world and all the people didn’t come into existence last Thursday, complete with false memories of a past that never really happened?
I group all these together because they are all pretty much just reformulations of the Cartesian Demon problem: the suggestion that the reality as we know it is a complete illusion, and instead the truth is (we are stuck in a computer / are dreaming / are a brain in a vat / only a few days old / at the whim of a Cartesian Demon). The response is still the same: it doesn’t matter.
As we said before, these hypotheses don’t actually suggest any differences in our world. They don’t say anything at all about goals we cannot accomplish. They don’t say anything at all about predictions that will or will not come true. They don’t say anything about coherence. They don’t say anything we could ever use to tell a Matrix-world from a non-Matrix-world.
There is not one experience we would have in the Matrix simulation that we wouldn’t have if our world was outside the Matrix. There is no difference between one of these fake worlds and our real world… not even in principle. Even if you had unlimited resources and knew everything you could possibly know, and had every possible experience, you still could not tell the worlds apart.
In short, these hypotheses don’t say anything we should care about. Ideally, the conversation with someone advocating, say, the idea we are all in a computer simulation should go like this:
Simulation Arguer: It’s possible that we’re in a computer simulation right now.
Me: How do you know we’re in a simulation?
Simulation Arguer: I don’t, but you can’t rule it out.
Me: I’m pretty sure I can rule it out. Just because I’m uncertain about the existence of unicorns doesn’t mean I can’t say “unicorns don’t exist”.
Simulation Arguer: Still, don’t you think it is at least remotely possible we’re in a computer simulation?
Me: I have no idea how I could even tell. I don’t think your idea is false, I think it’s meaningless. What experience do you anticipate having that would demonstrate to you that we’re in a computer simulation?
Simulation Arguer: I don’t know, I just think it’s possible we’re in a computer simulation, and you haven’t said anything to give me certainty that we’re not.
Me: That’s a bad standard, I don’t think you’ll ever find certainty in anything. For all you know, you could even be wrong about the fundamental principles of logic. Until you can point out a difference between a simulated world and a non-simulated world, you’re not really talking about anything that can possibly matter.
What About Solipsism?
Solipsism is the idea that other people don’t exist in the same way you do — that other minds are an illusion and you’re mind is the only one you can be sure is real. Like the other Cartesian-like hypotheses, Solipsism isn’t seriously held by anyone, but is widely considered to not be something you could ever rule out.
Instead, like the other Cartesian-like hypotheses, it is also meaningless, for there is no experience solipsism predicts that wouldn’t also happen if solipsism were false. Even if you think other people are illusions, they will still act as if they aren’t illusions, will still get offended at being called illusions, and can still punch you in the face and make you hurt.
Solipsism entails nothing different about the world that you could ever know of, even in principle.
But What if it Was Meaningful?
But just because these hypotheses are currently meaningless doesn’t mean they can’t be meaningful. Any meaningless hypothesis can become meaningful really easily — suggest an experience we could anticipate having, or an experience that would be ruled out and we could anticipate never having.
For instance, the meaningful dream argument might suggest we could lucid dream, and start flying merely because we want to. The meaningful Matrix argument might suggest we could find Morpheus and take a pill and wake up. The meaningful Demon hypothesis might suggest we could find the Demon and talk to him, or have him give us a completely different set of experiences on demand. The meaningful solipsist hypothesis might suggest we could make people disappear by ceasing to believe they exist.
If we had these experiences, these Cartesian-like hypotheses would start being meaningful, and we could determine if any of them are true. But they aren’t meaningful like that, and even if they were, we could easily test them and find them false. So stop worrying.
The Idea of an External Reality
All of these Cartesian-like hypotheses may not be meaningful, but they do demonstrate something important about this theory of knowledge: experiences are the only thing that matters, regardless of where they take place. This means that it doesn’t matter whether or not we have access to an “external reality” or not.
For what does “external reality” mean? All it seems to imply is that things will be true or false regardless of what we believe. More simply, our predictions will come true or false no matter what we think of our predictions, as hard as we wish we can’t suddenly make “I am capable of faster-than-light travel” true. As long as our beliefs are independent from our experiences, there is an external reality, even if that external reality is simulated or created by a demon.
Statements are meaningful if they make predictions about what will and will not happen, regardless of whether or not that’s a prediction about the actions of a Cartesian demon or the actions of an external mind that you can’t really have knowledge of.
Scaring Away the Demons
While I just talked about the wrong way to deal with Cartesian-like hypotheses — namely, worry about them or hold them up to be a possibility we could never rule out — there is a right way. We can figure out what experiences to anticipate that would lead these hypotheses to become meaningful, and then attempt to test them like any other hypothesis. We could figure out what exactly it means to be in a computer simulation for those inside the simulation, and then attempt to verify it.
Until then, let this be the end of Cartesian Demons and all their associated worries, for we have nothing to fear from something that truly doesn’t matter in any way.
Followed up in: Knowledge: A-priori and Absolute and Clarifying the Idea of Meaning
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Peter,
I enjoyed reading this essay but I think your analysis of meaning is vitally lacking a key component. I have read “Meaningfully True” and think that it is a good criteria for truth, but not for meaning. You have assumed the two to be synonymous, but what I will argue here is that there is a second type of information that is meaningful but not true.
You state, “…Meaningful statements are those statements which say that certain experiences will occur and certain experiences will not occur, the true statements are those where the experiences which must occur do occur and the experiences which must not occur do not.” This assertion parallels your argument in “Meaningfully True” that
“any statement that is meaningful will entail some experiences must occur and some experiences must not occur”
This statement is false. There are plenty of meaningful statements that provide no prediction of future experience at all. I am for the purposes of this response calling these “motivators.” A motivator is a statement that provides rules for action. Of course truth statements are types of motivators, especially in our increasingly scientific world. There are millions of people who determine how to act based on what is “true.” However, the same millions of people also undoubtedly perform huge symphonies of action based off motivators that are not truth, but myth.
I’ll provide an example to solidify this idea a little more. Jimmy is a first year college student. He is trying to figure out what he should study and ultimately what he should do with his life. Through the various steams of information that Jimmy has taken in over the course of his 18 years he has developed the myth that “Journalism is cool, and that he would be a great journalist.” Jimmy is convinced that he would be a great journalist. Now let’s look at this conviction. Is there any truth behind it? No. Jimmy has not so much as worked for the high school newspaper, in fact he does not even read the news. Let’s say even if he had done those things, working for a high school newspapers only in the most remote of ways represents what is required in a career of journalism. To the point where even if he had had such an experience it would not help him at all navigate an actual career of journalism. I
By your criteria of meaningful statements Jimmy’s statement ” I will be a great journalist” is not meaningful at all. Thinking journalism is cool and that he is suited for it provide no knowledge of what experiences will or will not occur. And yet, Jimmy is adamant about this belief, he KNOWS that it is meaningful, and thus is unyielding in his possession of it. Fast-forward 8 years, Jimmy is now a journalist. Not the most successful, but his relentless belief in the myth of his capacity for journalism motivated him to enter new territories, with new experiences that allowed him to develop real, meaningful truths about what it takes to be a journalist.
Motivators do not need to be true. A strong enough faith in the validity of a motivator pushes the believer into situations that allow her to harvest truths that are beyond her current reality. Back to the example of Jimmy, no matter what truths he contained at the start of college, no matter what beliefs, without some motivation to pursue classes on journalism or related opportunities the chances that he would have encountered the opportunities to harvest meaningful truth about journalism are slim to none.
I argue that this is not a unique scenario. Most people exist within limited territories that are not as ample for the harvesting of truths as a college campus. To reach a certain plan of meaningful truth (and by this I do not necessarily mean higher truths, but rather truths out of the reach of immediate practice) a person needs motivators to push them towards new territories of knowledge.
Now let’s return the above essay. You make the argument that whether the demon exists or not doesn’t matter. I do not know how familiar you are with pragmatism, but from my understanding of it, this seems to take the cake. William james in his lectures on pragmatism states:
“The pragmatic method is primarily a method of settling metaphysical disputes that otherwise might be interminable…The pragmatic method in such cases is to try to interpret each notion by tracing its respective practical consequences. What difference would it practically make to anyone if this notion rather than that notion were true? If no practical difference whatever can be traced, then the alternatives mean practically the same thing, and all dispute is idle.” (James 1995 [1906]).
Correct me if I am wrong, but it seems like this is what you are arguing. Whether there is a demon or matrix either way we experience the same information and thus can rationally organize it. As a side note I would like to say that this position still does not address the potential that the demon can manipulate not just sensation external to you, but the processes of your internal cognition. But we will ignore that for now, for the brunt of my argument is not a tit-for-tat about the nature of said demon, but about motivational power of a belief in said demon’s (or matrix’s) existence. Someone who does believe in an external reality of sorts will be motivated to take monumentally different course of action than a person who does not. Because of this you cannot say the discussion does not matter. It does not matter to you because you have already made up your mind on the matter.
Seeing that you already believe that such an external reality does not exist you are not looking for one. Just as the person who does not think journalism is cool/respectable does not look for ways to be a journalist. You talk about something being testable in principle vs. practice. But what I argue is that almost EVERYTHING starts out testable only in principle. There was a point as you state where testing to see if the earth was round was unimaginable, and so many people let go of that idea. However, those who refused to let go are the ones responsible for pushing humanity in a direction that eventually positioned it to be able to test the shape of the earth in practice. Returning again to the demon/matrix the stipulation that the demon is all power, rendering any effort to contact it/ escape its artificial reality, is a ludicrous addition to the argument that reflects only the religious undertones of cartesian philosophy. For nothing in this universes short of a profound faith in the constitution of an almighty god suggests that any such infinite or eternal body exists. If there is a demon only your religious belief render him immovable (be they beliefs in a god or in the history of western philosophy). Removing these things, it is perfectly justified to assume that if there is a demon or a matrix there is a way out. Now I am not saying that there is such an external reality, or that if there was an external reality we as humans would be able to escape it. What I am saying is that no such argument can be made. Therefore to belief in the myth of an external reality would justify drastically different actions than to not. And those actions COULD lead to an escape into the “real world” such as in the matrix.
You are correct in stating that currently such a theory is testable only in the most abstract of principles, but you are false in assuming that the pursuit of more practical means of testing is futile. For to be able to say that pursing more practical means of testing the validity of this reality is futile is to posses knowledge of the constitution of reality, which is something you, nor any other human posses at this time.
To summarize, the existence of a Cartesian demon, or the matrix, or whatever is a valid concern because of its potential as a motivator of human action. It cannot tell us anything about what we are experiencing and what we will not experience; but it can shape what we have the potential to experience. It shapes where we devote our energies and other various resources, which have a real impact on our lives and our world.
If I took the matrix/demon reality seriously I would perhaps be on my way to tibet right now, working as a ghost hunter, or studying sub-atomic particles with vehement enthusiasm. It would be a different life, expose a different body of knowledge, and potentially move humanity 1 step closer to truly being able to solve this dilemma.
Now that said, to all those reading this I actually do believe that it is a waste of time to pursue the cartesian demon. But this is not my truth, it is my faith. It represents not what I know about the universe, but what I have chosen to make my ultimate concern. And I do think there is some reasoning to choosing to ignore the demon scenario over devoting your life to it. That being that I don’t see this life as demonically created, I see it as being overwhelmingly beautiful. I love my family, I love my friends, I love the journey I am undertaking, I see no need to look for an exit. I will leave the development of knowledge on the matter to those individuals who do see the world as devised by a demon and want nothing more than to escape.
– Tom Mitchell
“Solipsism is the idea that other people don’t exist in the same way you do — that other minds are an illusion and you’re mind is the only one you can be sure is real. Like the other Cartesian-like hypotheses, Solipsism isn’t seriously held by anyone, but is widely considered to not be something you could ever rule out”
Asking you, because the problem is plaguing me:
1) Can agnosticism to Solipsism be avoided?
2) Is all metaphysics you have come across such meaningless, unfalsifiable bollocks?
I’m sorry, but I don’t understand this question.
~
Sort of. I’m not sure how I go about metaphysics since I do consider myself a metaphysical naturalist, but I’m only a naturalist because there seems to be no way I’ve encountered to establish that the supernatural stuff (a) exists or (b) is even coherent. So that leaves only natural stuff.
But natural stuff could still be nearly anything: dark matter, neutrinos that might exceed the speed of light, or who knows what they’ll discover next.
So my metaphysics flows easily out of my theory here about truth: if you can’t demonstrate it, it’s not worth saying it exists.
And I thought the british slang would make 2 harder to comprehend.
I’ll try to reframe 1:
1/ Do you know if solipsism is true, or not?
My answer is you can’t (though I have a gut feeling against it) logically as it is non-falsifiable. My gut feeling could probably even be explained by solipsism. Therefore if someone asks me (logically), “do you believe in solipsism?” I feel I must reply “I don’t know, I don’t think it makes any difference”.
The point came up when over at TWIM I established that Crude, though he/she did not believe in a distinction between natural and supernatural, did not believe the “supernatural” world was open to empirical test. I replied “so you just want me to have faith in them” and he replied “you have faith in an external world, you can’t disprove solipsism, last thursday-ism empirically”. If that helps.
On point 2, yes, I operate in accordance with naturalism, but then some philosopher will always say something awkward like “define what it is to be a physical object/ a physical property necessarily entailed by a physical object”.
A dualist (whilst not sword-fighting) could as easily claim that all that they see is explained by their metaphysics, all a naturalist could argue is you can’t see these “mental” events as seperate from physical events, the dualists would just say “if you could fiind them by physical means they would be physical events, not mental events”….
I’ve watched my share of Monty Python.
~
I think this question goes away easily when one counter-asks “what testable predictions does solipsism make of the world?” or “what does solipsism say about the world that I will either experience or not experience?”
If you can’t root solipsism in that experience, and I think you cannot as I argue in the above essay, you end up with a statement that is not truth-apt and therefore meaningless (not worth discussing).
So, in a logical argument, even:
P1: Solipsism cannot be demonstrated to be true or false.
P2: You can only say something is true or false if you demonstrate it to be such.
C3: Therefore from P1 and P2, you cannot say solipsism is true or false.
P4: You can only have a belief in X if you think X is either true or false.
C5: Therefore from C3 and P4, you cannot believe in solipsism.
~
Exactly.
~
That does help, and is very damaging to Crude’s case. Crude has shown you that he actually has no reason to believe in the supernatural, because it means he is believing something he cannot demonstrate, which will be a contradiction and therefore completely unjustified.
You’re right you can’t disprove solipsism or last thursday-ism. But such things aren’t even truth-apt; no one can prove or disprove them. The only right attitude is to disregard and ignore them: a universe that came into existence last Thursday is identical to a universe which didn’t, so who cares? We live our lives the same.
If Crude thinks existence of the supernatural isn’t truth-apt, then he ought to abandon his faith. If Crude disagrees and thinks existence of the supernatural is truth-apt, then he ought to demonstrate the supernatural.
~
It is kind of awkward, but it’s a complete red herring. You aren’t ruling out anything you can define on naturalism, you are just ruling out a whole group of things that are incoherent and aren’t truth-apt.
~
I’m sympathetic to the idea that “well, if you could prove it empirically, it wouldn’t be supernatural”. That’s the whole point! That soul thing you keep telling me about? I as a naturalist will humbly believe it as soon as you demonstrate it. My brand of naturalism doesn’t rule out the existence of souls at all, as soon as we have a coherent and testable idea of what souls are.
You’ll note this has some slight contradiction with my essay “Defining the Supernatural and Supernatural”. That’s because these thoughts post-date the essay, and that essay needs revision. You can see this idea that the supernatural is incoherent stated in my other essay “The Magical Magician: A Naturalist’s Allegory”.
In summary:
1.) I have no definition of the supernatural.
2.) I don’t need one; I just need to rule out claims that aren’t truth-apt.
3.) Of the claims that are truth-apt, I weigh the evidence as much as I can and come to a belief about the likelihood of X being true, and then hold that belief.
4.) Some idea like solipsism or the soul could be ruled out by 2 or ruled out by 3, depending on how the idea is formulated.
“Therefore if someone asks me (logically), “do you believe in solipsism?” I feel I must reply “I don’t know, I don’t think it makes any difference”.
Exactly.”
Please be extremely delicate when relating this to Crude. I expressed this idea as agnosticism, and he seems to have withdrawn from conversation.
I was brought up as a Jehovah’s Witness, and was always threatened with
disfellowship/excommunication if my beliefs strayed too far from orthodox (among JW) doctrine. I never questioned the Elders to hard, but never got satisfactory answers. Now I am older, and less concerned about offending, I am still finding that my ideas warrant instant excommunicatiin among christians .
You’re ideas of “truth-apt”-ness, seem indistinguishable from falisifiabilty, not that I mean that negatively.
“you are just ruling out a whole group of things that are incoherent and aren’t truth-apt”
That seems to be what I did as a teenager, I ignored philosophy and concentrated on science. I was hoping philosophy (or perhaps the remnants of it) had something useful to say, about knowledge, perception, or the universe, I am increasingly finding the answer is “nox.
Thankyou.
I don’t know. I’ve had this discussion before, but I don’t want to talk about him without giving him an opportunity to defend himself.
~
It’s a classic defense mechanism to protect ideas that can’t be defended with legitimate reasoning that makes sense, and it’s what can distinguish religious approaches to defending ideas from scientific ones.
I qualify by saying that not all Christians shun disagreement or fail to defend their faith with reasoning, just that some do, and those some are annoying.
I’m glad you got out of the Witnesses and into thinking for yourself. It really makes life worth living to find out these things on your own.
~
It is, the words are pretty much synonymous.
Truth-apt is a word meaning “capable of being true or false”, and falsifiable is a word meaning “capable of being demonstrated false”, so anything that is truth-apt will also be falsifiable in principle.
I didn’t make up the word “truth-apt” by the way.
~
I think once you accept this dismissal of statements that aren’t truth-apt and then express a desire to focus on the empirics whenever possible and eschew armchair speculation, a lot of philosophy will become less useful to you. This is because philosophy is basically proto-science*, and probably should defer to science whenever possible.
But still, philosophy remains important in some areas if you know where to look and know how to do it well. Philosophy seems necessary to ground normative statements, however, so that makes philosophy really important to living our lives from that angle.
This makes me care a lot about the philosophy of ethics and epistemology, and a lot less about the philosophy of mind and religion.
~
*Note: Science did start out as natural philosophy, so we could say that science is really just a very effective part of philosophy that spun off from the ineffective parts. Our goal as philosophers and scientists is to turn the what is left of philosophy into science as well. A lot of people (including me) want to see this done especially with epistemological and moral statements.
“I’m glad you got out of the Witnesses and into thinking for yourself. It really makes life worth living to find out these things on your own.”
Oddly it was the belief that most people wouldn’t be saved that made me reject the idea of being saved, it didn’t seem right. It was nice to be (very gradually) freed from the shackles of Apologistic logic.
“This is because philosophy is basically proto-science*, and probably should defer to science whenever possible.”
I’m now massively biased to this viewpoint, following the realisation that metaphysics is not falsifiable/ truth apt.
Oh well, keep writing, keep questioning, keep free from a demon haunted world.
Aye, thanks man. Keep doing the same yourself, and feel free to comment here whenever you want.