The story so far: cl wrote a post that really piqued me (in the good way), so I responded and then things got hairy. Today I will be addressing what are, to me, the three most interesting things about cl's last salvo - knowability, a response to his argument from probability, and rhetorical gamesmanship. I'll close with a bit on truth, which I offer up as another direction in which the discussion might proceed.
First, a bit about knowability, which will touch on epistemology, the study of the nature and content of knowledge. cl posted an interesting logical argument involving this, and then clarified his meaning in a comment at my request (thanks for that, cl!). From what I can gather, cl and I agree in at least a vague way that the "awesomeness" of a claim has something to do with its grounding in experience: in his own words, "That which can be verified by experience is knowable; that which cannot be verified by experience is not." Or, as I say, "Knowledge must be grounded in empirical observation." However, cl then goes on to say,
We can make inferences about that which cannot be verified by direct experience - for example the claim that life exists in some other corner of the universe, or that George Washington was the first president of the United States - but that's it. Does this mean we can't "know" the planets revolve around the sun? In a sense, yes...Well, I actually agree with this as stated. However, we must also infer that our direct experiences as we remember them are valid in any way at all - and they in fact might not be. For instance, I may hear a voice and believe it is God, but it might also be the Goddamned Devil, or a person in another room, or my own internal narrator, or butt-puckering insanity - and at first blush, it seems awful hard to tell how some of these possibilities might be sorted out. This puts us in an interesting position with respect to truth (see below), but for now I shall simply say that not even direct experiences are immune to the leap of inference at which cl so precisely gestures, so long as those experiences are in the past (since all experiences not currently being had are in fact remembered - or misremembered, sometimes). It is self-evident, after all, that we do in fact have experiences, and anyone may verify this with the briefest of introspection - however, the content of those experiences, and their bearing on reality, are always subject to question. This is because, in short, we cannot directly perceive causality itself and may only infer it from the constant conjunction we perceive between suspected causes and their alleged effects (thanks, Hume!).
There is no getting around this. Thinkers of all stripes have tried, and failed, and whined about it (even me!); but we must all live with this doubt as our constant companion. As I said earlier, echoing Descartes: de omnibus dubitandum. So, if even direct experience is subject to question, what are we left with? I go with testability, which moves the goalposts for knowability quite a bit.
I realize that when I encounter an argument, or even a proposition, I do not decide whether to endorse it as logical or dismiss it as ridiculous right away - I first perceive either agreement or disagreement. It took me a while to get over this, but the instantaneous reaction I have of either "OK" or "No way" is itself a matterer of perception, at least in my own mind. Hell, others might be different. At any rate, if I have trouble determining whether I am perceiving thoughts of "OK" or thoughts of "No way," that's when I start to think about the claim itself. And I have agreed too readily to a great many things which I have later gone on to regret, ranging from trivial mathematical mistakes to the embarrassing thought that my mother must hate me for feeding me vegetables (I love vegetables now, and feel like an absolute twat for ever being a child, pretty much). But if, when I think about a proposition and then have difficulty trying to sort out just why I am perceiving agreement or disagreement with it, I then feel an urge to check. In the past, I felt the urge merely to decide.
Checking is important because then I can tell whether I am remembering something correctly or incorrectly. After all, I have mis-remembered in the past. So if I have trouble justifying a particular belief I hold, and can't remember what it was that made me think that in the first place, I then go see what I can check. And if I can't check to my satisfaction, I tend to withhold belief and write it off as unimportant - after all, that which leaves no effects to check is mighty difficult to call "relevant" on several well-respected definitions. This is more or less how I live my life, with respect to epistemology, anyway - more on this when we get to truth.
Whether or not you agree with cl's argument that it is more reasonable to believe that consciousness persists after death, I see a real gem of wisdom in there, which is a matter of perspective: cl's argument shows that, depending on how we define our terms, we can get to some surprisingly different conclusions about how we ought to form our beliefs. A great many people seem to form their beliefs - or at least a great many of them - in something resembling a binary truth table: X is true, Y is false, Z is true if A is not, B is true if and only if C is also true, and so on. Whether or not any particular person does, I cannot say, but this is in keeping with the overwhelming majority of my experience among humanity. When we say, "I don't know," most people usually mean, "I haven't thought about it," or, "I haven't decided."
Not me. My truth table has "true," "false," "not applicable," "I don't know," and "it depends." Other people might include "maybe," "probably," and "not if I have anything to say about it!" When I drop my hackey-sack, it falls to the ground: true. Two plus two equals five, for extremely large values of two: false (but funny!). This statement is a lie: not applicable (or "nonsense"). There is non-Earthly life in the solar system: I don't know. The Earth goes around the Sun: it depends on your frame of reference - if we define Earth's core as the center of our solar system, then of course the Sun goes around it, but then the rest of the planets and other stuff get a bunch of weird epicycles which we can rather handily avoid by adopting a heliocentric perspective instead. God exists: I don't know. God doesn't exist: I don't know.
Buh? Yeah. I don't know whether any sort of supernatural critter exists. I really don't. However, if some kind of supernatural critter did exist, then it would be this-or-that way, and not thus-and-such. In other words, it might be Thor-like, or Yahweh-like, or leprechaun-like, or FSM-like, or unicorn-like; and if it's one of those, then I sure don't want to pick the wrong one! But what if it's none of the ones that humans have come up with, and something totally different? What if it's aggravated by people believing in false gods, but has no "actual" religion of its own for followers to believe? What if it wrote no holy text, but instead tricked people into writing false ones? What if Richard Carrier's End of Pascal's Wager actually is the case?
I don't know.
I don't know, and so I withhold belief. In all of them, and in consciousness after death, and in live on other planets, and in parallel universes, and in any particular version of the maybe-even-not-approaching Singularity, and in a great many other things. Even if there is a supernatural critter, which there may well be, I do not believe in any particular one - and so I am not a theist. Since I am not a theist, that makes me an atheist. I am also an agnostic, because I don't know either way for sure, and so in that way I am an agnostic atheist; moreover, I'm skeptical of anyone who does think they have "all the answers" (or even a great many of them!), and so I am a skeptical agnostic atheist; and I'm a humanist, and a homo sapiens, and a house-renting-type person, and all sorts of other designations. But I am not a theist, for lack of evidence alone. I just don't know which way to go, so I don't go any way on that question. As for ethics, relationships, economics, and so on, well, my views get more complex and my "titles" keep on stacking up. But I am only an atheist because I am not a theist, I am not an atheist because I think I've "disproved God." Nobody can, that's just silly. I just won't believe until I can poke my fingers through some holes like the apostle Thomas.
A quick note on rhetorical gamesmanship before we get to truth. First, some may have noticed that I called cl a rhetorician and described his blogger's statement as platitudinous. I did each of these things for exactly one reason each: I called him a rhetorician because I thought I had discovered that the central motivating factor in his internet activity was honing his argumentative skill, and I called his blogger's statement "platitudinous" because some of his most interesting sentences sounded like platitudes to me. In the first place, I did not mean "rhetorician" as an insult, as I explained to cl in an e-mail; I think it is no bad thing to be concerned with how persuasive one is as a first priority, I think it is only bad if one then does bad things with such a skill. I mean, I want to be persuasive, for cryin' out loud, and so I too am a rhetorician. And in the second place, I was mistaken on the meaning of platitude! I thought "platitudes" were just simple-sounding phrases, more or less, some of which are trite and meaningless and some of which lend quite easily to deep wisdom. But I actually checked just now, and as it turns out, "platitude" only means the former thing (trite and meaningless), whereas I had honestly meant to indicate the latter thing (lending quite easily to deep wisdom). So yeah, foot-in-mouth for the win. Mea culpa!
So yeah, finally, on truth: there are two prevailing theories of truth in philosophical circles, the correspondence theory of truth and the coherence theory of truth. To steal Scotlyn's turn of phrase and boil a whole lot of argy-bargy down to one sentence, "correspondence" means "is the case in reality," and "coherence" means "is consistent with the greater body of true propositions." I couldn't tell you why this is a serious debate if you put a gun to my head, because both are important to me: true things ought to correspond to reality, I think, and true things also ought to cohere with one another. I think if either one of those is lacking, then you don't have truth; and if you can only get one but not both, then any claims to truth are suspect. So when I check to see if something is or is not the case, I'm satisfying the correspondence quotient; when I integrate that bit of knowledge with the rest of my knowledge, I'm roughly checking for coherence. They both matter.
So when I define "knowledge" as "justified true belief," understand that "true" means both "corresponds to reality" and "coheres with other true propositions." So for a claim to be "knowable," to me, means that I have to be able to get a justified true belief out of it. If I don't believe it, I can't be said to know it; if it's not true, then I can think I know it without actually knowing it (and even justify that thought process); and if it's not justified, then I merely believe a true thing without knowing it. That last one's sketchy, so here's a quick example: I've believed that the Earth is round as long as I can remember, but I also remember that I was told so by my teachers and parents. As I began to question my teachers and parents, I found that they were not always right on things (such as math teachers insisting that the French word macabre is pronounced "MACK-uh-bray" and not "muh-KAHB," despite the correction of a seventh-grader such as I was at the time). Yet I never stopped believing that the world was round, even after losing my justification; instead, I learned how Eratosthenes calculated the Earth's circumference while trying to check whether it was round or flat, and so found a better justification.
Sometimes I have had to revise my beliefs based on observations so that they cohere with others, as alluded to above on why "checking" is important. As an easy (and real) example, I used to have many fears and superstitions as a child, some of them based on things I was told by others. I heard from my mom that ending microwave oven cook times in zero (such as 1:30, 2:00, etc.) would result in your food getting burned, so you needed to end cook times in non-zeroes. I don't know why I ever listened, but one day I actually checked by seeing how long cookies took to burn in a microwave, and I found two interesting facts: first, that cookies burn within a few seconds of the same general time, no matter what digit is last when the machine starts cooking; second, that my mom was wrong on this matter. So I wrote off what I thought was a whole bunch of superstitious hogwash along with that, and now we fast-forward to last year when my then-roommate, Amy, tells me that cool water boils faster than warm water, and warm water freezes faster than cool water. I called bullshit, because I had tested many of the superstitious claims I'd gotten from my mom, but then I went and checked: turns out, the Mpemba effect is real!
Sometimes, bullshit-sounding claims are actually true. But you can never know for sure until you check, and you shouldn't believe if you can't check yet.