April 28, 2011
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Can you prove the external world exists?
Intro:
This series is an atheist's review of an important skeptical anthology aimed at Christian beliefs called, "The Christian Delusion: Why Faith Fails" (TCD), that is likely to be popularly discussed across the web. I'll be reviewing the book in light of just about every other response to TCD on the web (pros and cons) and responding to new Christian objections as I find them. I think this will be the best that I personally can contribute to improving the online dialogue between Christians and non-believers on popular battleground issues.
It seems that in order to deflect away from the primary skeptical charge of special pleading that atheist John Loftus' "Outsider Test for Faith" represents, Christian reviewers seemed to unanimously reach for any and all philosophical obstacles to throw in the way. "Why are we just being critical of Christian beliefs?" so many of them asked. Why not ALL beliefs? To the extent this isn't a disingenuous diversion from basic critical thinking in regards to the Christian faith, we'll explore one often used example that many Christian reviewers made use of.
Jayman777 objects:
Reppert notes that most Westerners are raised to believe in an external world whereas someone born in India may believe that the external world is just an illusion. Should we not subject our Western beliefs to the OTF ["outsider test for faith"]? Loftus begs the question when he asserts that the existence of the external world is experienced every moment we are alive. He tries to rely on the consensus of scientists but scientists merely assume the existence of the external word, they do not demonstrate it. This issue is a philosophical issue and Loftus cannot skirt it with appeals to probability (how could you calculate a probability in this case?).Paul Manata raises the same objection:
Or, more troublesome, the counter example shows that we should have the same level of skepticism towards, say, the philosophical belief that the world is maya as we should have towards the philosophical belief that the external world exists and is mind independent.David Marshall didn't even seem to formulate his coverage of this issue into an actual argument against Loftus' position:
I think Loftus is confusing a particular movie with the scenario it illustrates. It is certainly the case that some intelligent people DO take the scenario that the world is some sort of simulation seriously. One atheist philosopher, another told me, put the odds of the world being unreal at about one in five. (Don't ask me how he calculated this -- taking the rationality of his own brain for granted, still!) I believe in the reality of the external world -- that's why I'm blogging. But Keller and Craig are right to say we can't prove it -- nor do Loftus' arguments manage the trick.
So he pokes fun at one atheist for pulling ratios out of his/her existential arse, notes two Christians can't prove it, and then notes that Loftus can't either. So what? Is this where superstitious Christians are "just supposed to know" that magically their belief in a god gets them around this problem? I want my "get out of philosophical problem free" card, too, please!
After John Loftus confronts jayman777's review, jayman777 replies:
I am not denying that there is an external, material world. I am saying that your defense for the existence of an external world fails. That we perceive a world in front of us is no surprise to the Indian in Reppert’s example and thus gains your position no advantage in the debate. Unless you can provide a better argument, Reppert has shown that your own beliefs fail to pass the OTB ["outsider test for beliefs"]. If you are going to muster a better argument, I think it will have to be a philosophical argument.Yup. And this isn't hard to do. I let Loftus' somewhat lame answer slide as I read through the chapter, but atheist Richard Carrier addresses this more directly in his book, Sense and Goodness without God (page 52):
On the other hand, if the [Cartesian] demon were really this consistent in giving us results, through which we satisfy our every goal and desire, there would hardly be any intelligible difference between what we call “reality” and the world the demon is inventing for us [or in this case an illusionary world]. As noted in II.2.1.2 (“Meaning, Reality, and Illusion”), such a construct would be reality, in every sense of the word we normally use. And since we observe some methods to work better than others, and indeed some work best of all, a Cartesian Demon would have to be arranging it this way, constructing reality for us solely in accord with a fixed plan it has chosen. In that case we have just as much reason to pursue the relevant methods for discovering that plan, and to abandon the bad ones, so we can gain the reward of a successful life experience from this mischievous demon. In other words, there is no reason to trust that any Cartesian Demon theory is true, and even if it is, nothing significant changes for us regarding method.That passes the Indian OTB since the persistent distinctions in our collective illusion are common ground.
I noticed one commenter on Loftus' blog said:
I don't think it is possible for us to know if we are brains in a vat or in the Matrix. How could we possibly know? That is also the consensus of contemporary philosophers. See David Chalmers.
I'd like to see the references on that just out of curiosity.
Into the Matrix:
Manata says:
In response to the claim that Loftus needs to take the outsider test for his belief that the external world is an illusion, Loftus says that before he takes that test the challenger must show him that his belief in a mind-independent external world is "probably false" (95-96). Loftus holds the position that the response to the person who claims that your belief could be false is, "So what? Give me good reason to believe that it is false" (96).For this thought experiment, we'll call one party Thomas Anderson and we'll call the other party Trinity. Now, Trin and Tom both have something in common. As Carrier pointed out above, they share the pattern
of what Tom calls "reality" and Trinity calls "the Matrix." So they are both insiders as far as that pattern goes as I'm sure they would agree. However Tom is an outsider to what Trinity calls "the real world." Even if Trinity is completely confident that what she calls the real world is in fact the real world, it may not seem to make much sense for her to take an OTF (Or in this case, it would be an OTB). We're not dealing with faith here, just her holistic past experiences of actually being unplugged and discovering an apocalyptic world that is hosting a computer simulation for most humans. However, she can still take the test. She doesn't need to get all indignant about it like Manata does. It's just the fact she's going to pass so easily because she'd be using all the same standards of evidence that Tom uses for calling the Matrix real applied to her very obvious experiences from outside of the Matrix. This is a technicality, but the point is, she can do it. There's nothing logically impossible about it. And more importantly, for Tom's sake, if she wants to make a more convincing argument without just unplugging him, she should be prepared to expose him to really good reasons for believing they are currently in a simulated world. She needs to be able to look at things from his perspective and not just pretend like her assertions are going to be credible based on Tom's background knowledge. Her reasons would need to be based on reasonable standards of evidence in that context. Why is that? Well, incidentally there's another example from the animated anthology The Animatrix. Specifically, in "A Kid's Story," we find a young man named Michael Popper who doesn't seem to have very credible reasons for thinking
he needs to wake up from the Matrix. Is a vague mystical notion that reality isn't as it should be, having bizarre existential conversations with a random person online, and being chased through school by some government agents a good enough reason to throw yourself off of a building believing you will wake up in the real world? Would Mike, the day before the story takes place, have a convincing case that passes an OTF if he were trying to convince another student that the Matrix is real? Probably not. As far as epistemology goes, being correct about the Matrix was an accident (which is what makes this segment of the movie kind of disturbing, since this is cultish thinking). He probably shouldn't have believed it himself. Plenty of people have all sorts of mystical notions and convoluted escapist intuitions. And there are plenty of people online who are willing to feed your choice delusion. Getting mixed up with the authorities for some reason or another could happen by chance. If the Matrix is anything like the world we know, then there would be all sorts of people who believe all sorts of crazy things that go well beyond what is immediately evident to all. Responsible people know that and are willing to re-think their grasp on reality accordingly.People like Manata can pretend like their convictions about Christianity are based on personal evidence that is much more like Trinity's situation than Mike's. It's doubtful that's actually the case. On the other hand, if I'm mistaken about that, it seems they could easily get into some convincing detail and they'd never bother appealing to anything like faith. They would also more readily respect how outsiders should view what they say and construct meaningful ways to bridge the gap of credibility to the best of their ability. And if for some inconvenient reason this simply can't be done, they would respect those unfortunate circumstances like rational caring people do and they wouldn't waste everyone's time arguing with assertions. Rational, caring people conclude, "You know what? I wouldn't believe me either if I were you."
The point is, the OTF still applies in either event. Neither a Trinity, nor a Mike should have much to fear from it. Especially, to mince analogies, if they are backed up by a loving god who likely wouldn't put them in inconsiderate epistemic circumstances to begin with. Then again, that's why Christians have the problem of "divine hiddeness." Maybe they should fear the OTF since they have everything to lose in the world of intellectual credibility.
Outro:
In ordinary life, the less people can verify my own claims, and the more it would cost them if they believed me, the less I naturally expect them to take my claims seriously. I may still have to believe my own experiences (since the real world example I'm thinking of would be unverifiable mental/emotional states that impact interpersonal conflicts) since I personally can't deny it, but I respect the fact I would be asking others to potentially go out on a limb. That can be a struggle, but that's just how it is. Welcome to what we call reality.
Ben
Comments (8)
While it is true that most Western thought is realist at some level, (1) antirealist thought would never support theism, and (2) skepticism of realism can support the notion that certain methodologies are insufficient to account for certain phenomena, the burden still rests on the theist to show how their phenomena exceeds our capacity for measure. Nothing is gained by simply saying one just needs to take a different metaphysical position tout court. David Chalmers is popular for a number of things, including his philosophical zombie argument. I forget from which literature it originated, but I couldn't stand the argument (compared to, say, John Searle's philosophy of mind). Nevertheless, Chalmers is not mainstream. He is a dualist. He hasn't written anything specifically on the brain-in-a-vat, but he has written a matrix paper.
There is a fundamental problem with saying that we lack the necessary tools to evaluate the truths of or about our reality. This reminds me of Godel's Incompleteness theorems for logic. The idea is simple. A formal system is complete if it is "big enough" to include all its truths, for a formal system can only prove things (theorems) from the formal apparatus it provides. Proof is a syntactic property. But truth is semantic and the formal system is used to represent things like, say, the system of natural numbers. So suppose we have a finitary system (i.e., one with a countable number of symbols, countable size of premises to its rules of inference ... everything is at most countable). Then every theorem must be a well-formed formula of this system (wff), and since every such wff is countable, the possible theorems are all going to be of countable size. However, one can show that the truths of the natural numbers is uncountable. So if someone says this system expresses the truths of the natural numbers it must be incomplete. It is impossible for a countable system to contain an uncountable many truths. It is not "big enough" in that sense. Therefore, Godel used this fact to show that such systems expressing arithmetic will have arithmetic truths that are unprovable (not theorems) of the system.
How does that apply here? We are not so limited as formal systems. Reality is much more complex than our abstract representations, and one would have to pull an amazing argument out of their ass to say that it is inconceivable for us, within a possible Matrix, to use the apparatus of that system to derive truths about the system. To say as much would require saying that there are properties of reality (or the Matrix) that exceed our limited ability to conceive of them with the tools at hand. Not so much that we're ignorant and haven't accessed those properties, yet. It is the stronger claim to saying that in principle our ability can only capture things of a certain size of which the properties of this system exceed that size. Our knowledge cup, in effect, is smaller than the pitcher of reality that pours into it. I'm not saying one position may be more plausible than another, but we have no way of really justifying it.
The fact is that this argument against the external world amounts to saying "we have nothing to say." It's the sort of skepticism that leads to sophistry. Even the antirealiist doesn't say "we've got nothing." That's a false dilemma. Instead, the skeptic should be saying "I don't think that world is what you think it is." Moreover, they can add, "your reasons for thinking it is the way you think it is are not unproblematic." For instance, the antirealist (for which there are two: antirealism against the entities and their existence, and antirealism against the theories about the world so described) can point out that the realist tries to claim their theories give us the best picture of reality because their theories are true. The realist, in this sense, is like a Biblical realist. The book of the world so manifest to the scientist should be taken as literal as possible. The antirealist is basically the non-literalist, but they usually just give a more liberal interpretation, maybe they are agnostic. The form of sophist skeptic I mentioned earlier would basically be the staunch atheist: "there is nothing we can say about reality, done." That, however, would be a bad argument.
I was reading Wesley Salmon's Causality and Explanation a few months ago. He is definitely a realist, and he said something in one of his essays that I found so profound. It is, by far, the best argument for realism that I've heard. It basically was the point that certain physical constants (such as Avagadro's number) have been confirmed, not by some tentatively confirming instances, but through unrelated experiments decades apart with entirely different intents; experiments that aimed to solve one thing while still producing a result that coincided with other unrelated theories and results. In effect, there are times where we see a convergence due to causal relations that pinpoint certain almost invariant properties. Now, I'm not saying they're invariant. Constants change, at least with respect to their significance (we adjust them to our technological precision). Salmon demonstrated three entirely different experiments that all generated Avagadro's number, for instance. All three had nothing to do with each other nor were in the same time period. They all used different methodologies and underlying theories. Yet, the causal apparatus of the experiment produced the same causal reality. That is powerful stuff, and I lean toward antirealism! It's not an argument for realism, but it certainly does suggest "there's something out there that can be latched onto." The naive realist, however, tries to just posit it absolutely and suggest we access it. In fact, we access it rather directly with correspondence between our ideas and what we perceive. Thus, what we perceive is true. That's a horrible account for realism, and Salmon's account at least provides a correspondence; not one of truth and perception, or one of manifestation and theorizing. Salmon suggests that there is a causal nature to the things we perceive that we have access to. Even antirealists would agree to that, and while we can be skeptical of our theories and the entities they posit, one cannot argue against experiment that causally tweaks one thing that causally produces another result. It is only through causality that we can, as philosophers say, "cut nature at the joints." If there is a nature, it has causal capacities we can understand. The skeptic that throws all that away is left with nothing.
Yea, I can.
@tjordanm - Cool! I'll let everyone know!
@WAR_ON_ERROR - Perhaps there isn't an external world, though, independent of the mind. The experience which we encounter is still caused by God.
@bryangoodrich - I'm not sure why the consistent measure of physical constants would be compelling since a Matrix or a Cartesian demon could account for the consistency and one is still in the same impossible bind. You can't prove it and there's really no reason to prove it. Practically there's no good reason to not take the world at face value unless given some specific reason to doubt it. But if someone wants you to prove positively that you aren't in a perfect reality scam, there's by definition no way to do it. It's just a natural and unavoidable weakness of any conscious being.
As you noted, this issue doesn't do anything for theism one way or the other. It's just something critics of the book threw in the way as distraction. The point is that we are all in the same boat...and we can still critically evaluate our other candidates for delusion.
@WAR_ON_ERROR - The problem with invoking that level of skepticism is that we're left with no basis to claim anything. Descartes invoked God to rid his mind of demons and Neo needed something outside the Matrix to reveal such truth. The fact remains, if all we have is Matrix-truth, then that seems to be truth-enough. If all we discovery does justify a sort of realism and it turns out to only be the Matrix, then we have the best we can obtain: Matrix-realism. We could not even say what is real beyond the fact that all that is consists of the Matrix. If we have means to achieve more, then we could say more. If we could travel to the "real world" then we could make real-world-claims. But it would never shed doubt on the fact that we have obtained justification of an external world, at least in context to ourselves, whatever "ourselves" consists, which may only be matrix entities grasping at the Matrix itself.
@bryangoodrich - I'm not sure why you perceive what I'm saying as overly skeptical and yours as less so. I don't know what we are saying that is different.
"Neo needed something outside the Matrix to reveal such truth."
This was true at first in the movies, but eventually no one was there to help Neo on the final leg of his journey at the end of Revolutions. He had transcended many corrupt paradigms and finally had to step out unguided into completely unknown territory (where even the Architect and the Oracle were grasping at straws) and submit to the consequences of his choices. It's the only reason I really like the third movie.
@WAR_ON_ERROR - My point was that if we're skeptical about everything, then we're left with nothing. If for everything we assert can be challenged by "but that was just fed to you by a demon," then no one can assert anything. There is a clear difference between that staunch skepticism that can only lead to solipsism and the sort of skepticism in science where we say "our conclusions are tentative at best and we should always examine our assumptions, methodologies, and conclusions." The latter at least admits of "whatever it is we're identifying, we can say it stands external to us." So even if it is all just us discovering the Matrix, we're still justifying the existence of an external world to which we belong. It just isn't the external-external world that could possibly exist. So raising the question if we can prove the external world exists hinges on what we mean by "external."