tag:blogger.com,1999:blog-3891434218564545511.post4449865896773370574..comments2024-03-28T19:56:42.305-05:00Comments on Alexander Pruss's Blog: The a priori and the a posterioriAlexander R Prusshttp://www.blogger.com/profile/05989277655934827117noreply@blogger.comBlogger11125tag:blogger.com,1999:blog-3891434218564545511.post-6648850770214090542014-03-19T16:31:13.607-05:002014-03-19T16:31:13.607-05:00Right: I am willing to say that unrevisability is ...Right: I am willing to say that unrevisability is incremental evidence of apriority. But I do not see that it raises the probability of apriority over 1/2.<br /><br />I think the propositions taught by the Magisterium have sufficient evidence to hold them, but holding them irrevisably might be thought to go beyond the evidence. (Or not. For there is the testimony of the Holy Spirit to be considered.)Alexander R Prusshttps://www.blogger.com/profile/05989277655934827117noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-1686713910303441492014-03-19T16:18:05.206-05:002014-03-19T16:18:05.206-05:00Suppose I learn that the card drawn from a fair de...Suppose I learn that the card drawn from a fair deck is even, E. The probability that it's a deuce given E is greater than the probability it's a deuce. But E is evidence for lots of other things. It's evidence that it's a 4 of spades or 6 of diamonds, for instance. So what if R is evidence for a proposition p being other things (like a proposition in the Magisterium, for instance), it might also be evidence that p is a priori. <br /><br />For what its worth, I had in mind propositions which we hold on the basis of evidence. I don't think you hold the propositions in the Magisterium on the basis of evidence. Further, I think it would be rational to hold that some propositions in the Magisterium are false, at least in their details. Probably, the fullness of divine truth is not quite, not exactly, what you find there, even if it approximates it.Mike Almeidahttps://www.blogger.com/profile/12001511002085064198noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-53857745939352815762014-03-19T13:30:48.003-05:002014-03-19T13:30:48.003-05:00I don't see why unwillingness to revise is evi...I don't see why unwillingness to revise is evidence of aprioricity. There are a handful of propositions I am unwilling to revise:<br />- some basic tautologies<br />- that I think<br />- the truths of the Catholic faith.<br /><br />Since the last category is full of a posteriori truths, I don't see how my unwillingness to revise is evidence of aprioricity.Alexander R Prusshttps://www.blogger.com/profile/05989277655934827117noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-85774150020292346412014-03-19T12:12:18.418-05:002014-03-19T12:12:18.418-05:00I think rational intuition is a sort of perception...I think rational intuition is a sort of perception. I think it is fallible. But I'd deny that all perceptual/quasi-perceptual knowledge is <i>thereby</i> a posteriori. Why would anyone think that? Is it apriori true? <br /><br />On your unwillingness to revise your beliefs concerning the validity of p --> p, I was not suggesting that you identify the unrevisable with the a priori. I was suggesting that the fact that you won't revise is evidence (under any evidential conditions) is evidence that you do not know p --> p a posteriori. Mike Almeidahttps://www.blogger.com/profile/12001511002085064198noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-8365417317395287352014-03-19T11:47:27.713-05:002014-03-19T11:47:27.713-05:00It's plausible that empirical knowledge is kno...It's plausible that empirical knowledge is knowledge by observation. If rational intuition is a kind of observation, then knowledge by rational intuition is empirical knowledge. <br /><br />Now, I suppose, one can distinguish the modes of observation. We have the usual eight senses: sight, hearing, smell, taste, pressure, temperature, proprioception and introspection, and then we have rational intuition. But why should the first eight all go in one category while the last goes in a separate category? One might think that the difference between rational intuition and sight is like the difference between sight and introspection, or between smell and proprioception. If so, then instead of dividing knowledge into the a priori and a posteriori, we should divide knowledge into the rationally intuitive, proprioceptive, olfactory, visual, etc.<br /><br /><br />I certainly don't think we should align the a priori with the unrevisable. It's not clear to me that my knowledge that I think is a priori (it seems to depend on introspection), but I see no way to giving it up. So there may well be unrevisable a posteriori claims. And there are plenty of very revisable claims from rational intuition.Alexander R Prusshttps://www.blogger.com/profile/05989277655934827117noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-53063116241629171002014-03-19T11:33:56.601-05:002014-03-19T11:33:56.601-05:00This comment has been removed by the author.Mike Almeidahttps://www.blogger.com/profile/12001511002085064198noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-52618388716116013582014-03-19T11:33:20.633-05:002014-03-19T11:33:20.633-05:00I think knowledge of the a priori do have somethin...I think knowledge of the a priori do have something like a perceptual basis. I don't know how 'rational intuition' became a weasel word, but it is roughly what I'd suggest is the basis. But it's too much to ask (isn't it?) that anyone offer an account of how exactly we know a priori truths? That's too hard. There's a lot of empirical evidence that we do not know them merely empirically. For instance, you would be unwilling to reject that p --> p no matter what empirical difficulties would be thereby solved (pace Quine). Mike Almeidahttps://www.blogger.com/profile/12001511002085064198noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-7486392386260575112014-03-19T08:34:30.986-05:002014-03-19T08:34:30.986-05:00Mike:
Sure, but do I have any other kind reason t...Mike:<br /><br />Sure, but do I have any <em>other</em> kind reason to think these things? For all we know, all our mathematical knowledge ultimately depends on principles we know only in this kind of way.Alexander R Prusshttps://www.blogger.com/profile/05989277655934827117noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-44950304728806556662014-03-19T08:33:23.768-05:002014-03-19T08:33:23.768-05:00Brian:
One can call this perception with a weasel...Brian:<br /><br />One can call this perception with a weasel-term like "apprehension" or "rational intuition", but it is just perception by another name. :-) Which is basically what you say. But I'll adopt the wording for convenience.<br /><br />Regarding your last point, it seems that once we draw the line between the necessary and the contingent as you suggest, then presumably any necessary state of affairs that can be apprehended will count as <em>a priori</em>. But, plausibly, <em>every</em> necessary state of affairs, or at least every necessary state of affairs solely about necessary entities, can be apprehended. But it seems that wateriness = H2O-ness seems a necessary state of affairs solely about necessary entities.<br /><br />And on the abstract/contingent approach, again identity between two abstract entities seems something apprehendable.<br /><br />(One might try to restrict apprehension to a priori states of affairs, but of course then we get circularity.)<br /><br />Maybe one could say that "H2O-ness = wateriness" is partly about the water in our lakes and rivers, and not just about abstracta / necessary beings, since the sense of "wateriness" includes something about lakes and rivers. But this explains aprioricity in terms of senses, and that's the opposite direction of the one Chalmers wants to take. Still, maybe there is something to it.Alexander R Prusshttps://www.blogger.com/profile/05989277655934827117noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-76750124202302951512014-03-18T23:51:14.254-05:002014-03-18T23:51:14.254-05:00These are great points. I might raise a small quib...These are great points. I might raise a small quibble about the word "perception" in the proposal, though. Suppose we say instead that there is a fairly natural epistemic relation, to which we might give the neutral label "apprehension" (or "quasi-perception"-- Russell uses "intuition"), which we bear to objects and states of affairs on both sides of the concrete/abstract divide. When we bear this relation to a concrete object or state of affairs, we call this "perception," and we call the knowledge based on it "a posteriori," "empirical," or "observational." When we bear it to an abstract object or state of affairs, we typically use a different word, e.g. "rational intuition," and we call the knowledge that results from it "a priori." This is mostly a verbal change, but when we make it, we will not be tempted to worry that "on this story knowledge of abstracta is observational and hence empirical," because "observational" and "empirical," like "perception" and "a posteriori" are, on this proposal, only to be applied when the objects in question are concrete.<br /><br />(An alternative way to draw the distinction is in terms of the distinction between necessary and contingent beings/state of affairs rather than concrete and abstract beings/states of affairs. This would result in similar classifications, with one major exception: Direct apprehension of God would count as perceptual/observational/a posteriori on the former proposal, and intuitive/a priori on the latter. I'm inclined to think that the question of which of these is correct is, in Sider's sense, not a substantive question, because this whole way of looking at things makes the a priori/a posteriori distinction shallower, less "joint-carving" than one might have thought. The more important distinction, I think, is probably that between knowledge directly based in apprehension and inferential knowledge.)<br /><br />Lastly: It's not clear that your proposal would make trouble for two-dimensionalism. Chalmers agrees that we know facts about abstracta a priori, but only provided we have non-twin-earthable terms/concepts for the abstracta, which we don't in the example "wateriness = H2O-ness." (I suppose he would insist on qualifying your proposal, saying that a priori knowledge is [quasi]perceptual knowledge of abstracta grasped under non-twin-earthable concepts.) An analogous case: Suppose I introduce the name "A," stipulating that it is to rigidly designate the Tim's favorite number, whatever it is. Supposing that number is 12, then "A = 12" is a fact about abstracta, but it's not a problem for 2D because "A" is twin-earthable and so "A = 12" is not a strong necessity. Brian Cutterhttps://www.blogger.com/profile/17059155559949747916noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-60540529283118484512014-03-18T17:05:07.272-05:002014-03-18T17:05:07.272-05:00It now looks like Two and Snake are on par: either...<i> It now looks like Two and Snake are on par: either both beliefs are a priori or both beliefs are a posteriori.</i><br /><br />It's really hard to see why. The fact that there is an a posteriori reason to believe p does not make p a posteriori. We all have some a posteriori reasons to believe mathematical propositions (our teachers told us they're true, for instance), but that does nothing to show that the propositions are a posteriori true. What makes them a priori is that there is evidence (not necessarily all evidence) justifying the propositions that is (in some sense) not derived from experience. So the fact that I have some reason from evolutionary history to believe p does not make p a posteriori.Mike Almeidahttps://www.blogger.com/profile/12001511002085064198noreply@blogger.com