I’ve been thinking lately about presuppositional apologetics, following (among other things) this post on Aron Ra’s blog. I’ve got the beginnings of an approach to addressing presuppositionalism, and just for fun I thought I’d throw out what I’ve got and see what kind of comments it gets. My approach is a bit Pascalesque [EDIT: Cartesian?]: I start with the premise that there is one presupposition we all share (necessarily so) and at least one fact about which we are each absolutely infallible. From these I believe we can build a rational system which will allow us to examine any other presuppositions we might make, and evaluate which of these, if any, are more likely to be correct than the others.
The presupposition we all necessarily share is that truth is consistent with itself. This means two things: first of all, negatively, truth does not contradict truth, i.e. that which contradicts truth is by definition false. Secondly and more positively, truth implies truth, i.e. discovering one truth opens up opportunities to discover more truth. Truth does not exist in isolation from other truth, but is interconnected and cohesive, enabling us to reason from a set of facts we already know to a set of conclusions we did not yet know or were not yet sure about.
The self-consistency of truth is a presupposition we all must necessarily share, or our attempt to discover the truth will be futile: we’ll be unable to distinguish what’s true from what is not, and unable to reason from any evidence to any reliable conclusion. If a believer wishes to deny that truth is consistent with itself, they’re certainly free to do so, however they must recognize that in so doing, they’re effectively conceding that atheism may be the truth after all. Sure, you may think the Bible contradicts atheism, and you may believe that the Bible is the truth, but without the principle that truth can’t contradict truth, you have no reasonable basis for rejecting atheism, even if it does contradict what you say is true.
As for personal infallibility, the one thing about which we cannot be mistaken is the fact that we exist. (Yes, Pascal René, I see you waving over there.) I know that I exist, and there is no way my knowledge could be a mistake, because if I did not, in fact, exist, then who is making the mistake? If we suppose that the giant Pokemon Snorlax is fast asleep, and is dreaming that I exist when I really don’t, then yes, that mistake could be made. But that’s not Snorlax being mistaken about his own existence, that’s a mistake regarding the existence of a third party—me. But in the first person, we cannot make that mistake. Each of us can know infallibly that we do exist, and that’s important, because truth is consistent with itself, which means that we can proceed from one truth that we do possess to the discovery of additional aspects of truth that we do not (yet) possess.
That’s as far as I’m ready to go at this point, but I think it’s an approach with some interesting possibilities, and with particular applicability to presuppositional apologetics. Your comments and discussion are welcome.
But how do you KNOW you exist?
That’s my prediction for the first presup comment here.
Or, “La, la, la, I’m not LISTENing!!” which is really the same thought expressed in different words. If I believe that I exist, and that belief cannot be mistaken, then I know that I exist. The only way to deny that is to refuse to give the argument any honest consideration in the first place.
Surely quantum physics contradicts your first presupposition that truth cannot contradict truth? QP shows that electron ‘A’is at position ‘x’ this is truth. However, electron ‘A’ is also at position ‘y’ which is also truth. By your presupposition, one of those statements must be false, when it can be shown experimentally to be true.
Chrissetti,
Only if you hold the (mistaken, in quantum-land) axiom that something can’t be in two places at once.
You skipped that step.
The presupposition does not require one of those statements to be false, nor does it require any of them to be true.
It simply requires that, should we find a rule that says something can be in only 1 place at a time, any other truth about reality we find should be consistent with that rule. If we can show that reality contradicts that rule (as QP experimentally does) then that rule is false, it might be useful when talking about bowling balls but when talking about electrons that rule can’t be applied.
So, not to pry, but what is the highest-level QM course you’ve taken? And did it cause you to switch majors? Because you are very confused about how it works. If you experimentally show that your electron is at x, you have just shown that it is not at y. No contradiction at all.
Also, if I’m a Pokemon dream, I’m fair certain it’s Jigglypuff doing the dreaming. Now hand me that microphone.
Oh, no formal QM education at all, just an interested amateur willing to learn!
Thanks to everyone else who commented to clarify ‘delocalisation’ My understanding was that until a waveform collapses in observation, a particle is simultaneously at both points ‘x’ and ‘y’ (and every other point in the universe until the observation of the particle’s history collapses all the improbable outcomes to leave one outcome)
Only for a very confused definition of “truth” under QM. It’s what happens when physical reality on certain scales doesn’t work in easy-to-imagine ways: we can describe a particle as being in a superposition of position eigenstates, for instance, but then we can’t really say that a particle “has” a position, and we particularly can’t say that the position described by a single eigenstate represents an independent “truth”. The contradictions show up when we overstep “truth” and project incompatible intuitions onto systems that operate in a weird-ass manner.
Seems to me the proposition that is contradicted by quantum physics is that nothing can simultaneously exist in two places. However, I don’t believe it contradicts the presumption that truth cannot contradict itself. It just shows that the reality of the pysical world is more complex than previously thought, and the earlier supposition needs to be refined.
Isn’t “I think therefore I am” what Descartes said, not Pascal? Or did Pascal say something similar?
Doh, I knew I was going to screw that one up, but then I forgot to go back to it.
So Rene Descartes sits down at an outdoor cafe and the waiter comes up and says, “Would monsieur care for a glass of wine?” and Decartes replies “I think not,” and promptly vanishes.
@2: no, because quantum physics doesn’t say that. Quantum physics says that the electron is typically delocalised and doesn’t have a unique spatial position at all.
You’re correct, but “delocalized” is an unnecessarily complicated way of putting it, in my opinion. Makes it sound like “quantum magic,” though I’m sure that wasn’t your intent.
An electron is a wave. Suppose you have, say, a violin string, vibrating with the note E, and someone asked you where on that string is the note E. Is it on leftmost end, or the right? Is it in the middle?
Well, that’s a silly question, you’d say. The note E is a wave, and it’s on the whole string at once. (And in the wood of the violin, and in the air, and in the ears of the listeners…) Waves don’t have pinpoint locations like that, it’s just not an idea that applies.
…though even “wave” is an analogy. Because reality on the very fine scale is under no obligation to act in ways that we can make sense of easily.
No, “wave” is exact. Schrodinger’s equation is a wave equation – i.e. it has exactly those mathematical properties that control the dynamics of waves. You’re quite correct that reality on its fundamental scale has no reason to conform to our macroscopic experience and intuitions, but as it turns out, in this one particular way it does. Now if you start asking what this wave is made of, or what its medium is, or the physical significance of its amplitude and phase, you start getting into wildly counter-intuitive stuff really damn quick.
Have you never bumped into a logic paradox?
Well, not to put too fine a point on it, but isn’t the point of logical paradoxes that they make impossible assumptions, and then the paradox comes along to demonstrate that your assumptions are impossible? So the thing that you accepted as true in the first place isn’t actually true?
Perceived truths can conflict, when you’re wrong about at least one of them. No actual conflicting truth there.
Would it disprove my point if I did? A paradox might contradict my point, but if truth does contradict truth, then the existence of paradox would not make my point untrue.
😉
Personally I think paradoxes are an artifact of the inability of language and linguistic-based concepts to fully represent the reality they describe. It would be interesting to put that informal hypothesis to the test, however.
Let’s get logical about this. Two identical statements must have the same truth value.
The other statement in this paragraph is false. The other statement in this paragraph is false.
Therefore … [get ready for it you doomed to Hell atheists] … Jesus. “I am the … truth ….” It’s simple logic. Sure faith helps, but with logic one can know with mathematical certainty. /poe
Pish, it’s easy to pick out the false statement. It’s the one that goes “Two identical statements must have the same truth value.” 🙂
Seriously, though, my proposition is that truth does not contradict truth. In order to serve as a counter-example to my proposition, you must first establish that the two identical statements you cite are (a) both true, and (b) contradictions of one another. I suppose (b) is easy enough, but I don’t see how you could establish (a). Since each statement requires assessing the truth value of the other statement before its own truth value can be assessed, neither statement is capable of possessing a truth value, and cannot therefore be either true or false.
Plus of course they’re not actually identical statements, in context, since each one is referring to a different sentence when it uses the words “the other statement.”
I think all you really need to presuppose is that reality (at least the bit we can experience) can be understood, therefore reason and logic. This seems obvious to me, but I’m not a philosopher.
The Christian presuppositional argument seems to be that since you atheists presuppose logic and reason to understand reality, it’s equally valid to presuppose that my imaginary friend/s is/are real.
It’s more like, since we presuppose logic and reason to understand reality, we already are presupposing god. Because god is truth and without him logic and reason wouldn’t work.
It’s kind of the philosophical equivalent of licking someone’s food when they’re not looking.
The catch is that in that case the god we are presupposing is Alethea, not Jehovah.
@2, Chrissetti:
No, QP shows that they’re both false, which doesn’t hurt Deacon’s point at all.
More specifically, QP shows that discussions of location, as applied to electrons, require a bit of nuance and probably math, to accurately reflect reality.
Frankly I think discussions of truth carry a lot of baggage, and prefer discussions of consistency. And I think it makes more sense to say “reality is consistent with itself” than to say “truth is consistent with itself”, because then your words actually refer to what you’re actually talking about.
In my opinion, the idea of “truth” unnecessarily (and harmfully) reifies that which is really just “a set of measurements”.
Can’t say I disagree with that. No matter how “true” something may be to someone subjectively, if it does not correspond to what actually exists in the real world, it is worthless, or at least worthless to anyone else. So if we try and force it on someone else, we’re guilty of promoting worthless “truths,” and are a burden on society. And that’s especially true if we succeed in getting other people to to buy into our worthless baggage.
Want to destroy a presup? Use their weapons against them. Right at the start say that logic reason etc. are “brute facts of reality,” throw their arrogance and their assumption that the opponent is borderline insane at them before they do it, and so on.
Basically, since it’s all bluster, learn their script and use it against them. It’s hilarious if nothing else.