1 00:00:00,012 --> 00:00:05,662 Today we're going to talk about Fallacies of Vacuity. 2 00:00:05,662 --> 00:00:13,667 An argument suffers from a fallacy of vacuity when the argument doesn't make 3 00:00:13,667 --> 00:00:21,097 any progress, doesn't go anywhere. There are two general ways this can 4 00:00:21,097 --> 00:00:25,618 happen. One way an argument could suffer from a 5 00:00:25,618 --> 00:00:29,885 fallacy of vacuity is when it begs the question. 6 00:00:29,885 --> 00:00:36,618 That is to say, when, in order to believe the premises of the argument, or to 7 00:00:36,618 --> 00:00:43,432 believe that the premises imply the conclusion, we already need to believe 8 00:00:43,432 --> 00:00:47,997 the conclusion. Without already believing the conclusion, 9 00:00:47,997 --> 00:00:51,847 we're not going to believe that it's a successful argument. 10 00:00:51,847 --> 00:00:56,347 That's begging the question. That's one way an argument could suffer 11 00:00:56,347 --> 00:01:00,872 from a fallacy of acuity. Another way an argument could suffer from 12 00:01:00,872 --> 00:01:05,122 a fallacy of acuity is when the conclusion doesn't say anything 13 00:01:05,122 --> 00:01:08,547 substantive. When a conclusion just says, for 14 00:01:08,547 --> 00:01:13,567 instance, well, either it's raining or it's not, something completely 15 00:01:13,567 --> 00:01:19,467 uninformative like that, something that doesn't provide you with any information 16 00:01:19,467 --> 00:01:23,812 that you wouldn't have known independently of the argument. 17 00:01:23,812 --> 00:01:29,085 Those are the 2 general ways in which an argument can suffer from fallacy of 18 00:01:29,085 --> 00:01:32,129 acuity. We'll first talk about begging the 19 00:01:32,129 --> 00:01:35,564 question. Let me start off by giving you a really 20 00:01:35,564 --> 00:01:41,232 simple example of begging the question. It's an example that's so obvious, that 21 00:01:41,232 --> 00:01:44,983 probably none of you would be guilty of this fallacy. 22 00:01:44,983 --> 00:01:50,245 Suppose you're in a strange city, and you're walking around, trying to find 23 00:01:50,245 --> 00:01:54,214 a particular street. And so you go up to a stranger in that 24 00:01:54,214 --> 00:01:59,132 city, a normal seeming stranger. And you ask them for the directions to 25 00:01:59,132 --> 00:02:04,023 this street that you're trying to find. And they say, oh, that street. 26 00:02:04,023 --> 00:02:07,032 that street is three blocks north of here. 27 00:02:07,032 --> 00:02:13,570 And now you think, well, the stranger said that that street is three blocks 28 00:02:13,570 --> 00:02:18,003 north of here. That street is three blocks north of 29 00:02:18,003 --> 00:02:21,569 here. Maybe you believe that because the 30 00:02:21,569 --> 00:02:26,299 stranger said it. And then from those two premises you 31 00:02:26,299 --> 00:02:36,128 conclude So the stranger told the truth. Now let's look at that argument. 32 00:02:36,128 --> 00:02:42,808 That argument has something puzzling about it. 33 00:02:42,808 --> 00:02:55,463 Premise 1, premise 1, the stranger said, the street is 3 blocks north. 34 00:02:55,463 --> 00:03:07,172 [SOUND] Premise (2) The street is 3 blocks north, 35 00:03:07,172 --> 00:03:17,333 [SOUND] where premise two is something you believe, because that's what the 36 00:03:17,333 --> 00:03:26,308 stranger told you. And from those two premises, you draw the 37 00:03:26,308 --> 00:03:38,277 conclusion, the stranger was telling the truth. 38 00:03:38,277 --> 00:03:47,736 Now, notice something funny about this argument? 39 00:03:47,736 --> 00:03:53,077 This argument actually is valid. There's no possible way for the two 40 00:03:53,077 --> 00:03:59,335 premises of the argument to be true, if the conclusion, number three, is false. 41 00:03:59,335 --> 00:04:04,060 If both premises are true then the conclusion has to be true. 42 00:04:04,060 --> 00:04:09,225 So the argument is valid. Furthermore, we can imagine a situation 43 00:04:09,225 --> 00:04:13,927 where the argument is sound, because both of the premises are true. 44 00:04:13,927 --> 00:04:17,447 Right? If you really are walking around a strange city, 45 00:04:17,447 --> 00:04:21,997 and the stranger tells you that the street you're looking for is 3 blocks 46 00:04:21,997 --> 00:04:24,817 north. And, in fact, that street is 3 blocks 47 00:04:24,817 --> 00:04:27,377 north. Then, both of the premises of the 48 00:04:27,377 --> 00:04:31,227 argument are true. And so the argument, in that event, would 49 00:04:31,227 --> 00:04:33,032 be sound. Nonetheless, 50 00:04:33,032 --> 00:04:38,640 the conclusion of this argument is not one that you ought to believe on the 51 00:04:38,640 --> 00:04:43,190 basis of these premises. Now look, you could have all sorts of 52 00:04:43,190 --> 00:04:48,253 good reasons for believing this conclusion, for believing that the 53 00:04:48,253 --> 00:04:52,946 stranger told the truth. For instance, maybe a friend of yours 54 00:04:52,946 --> 00:04:56,412 could vouch for the strangers reliability. 55 00:04:56,412 --> 00:05:01,819 Maybe the stranger has an excellent track record of telling the truth, and people 56 00:05:01,819 --> 00:05:06,881 could tell you about this track record, alright? There could be all sorts of 57 00:05:06,881 --> 00:05:10,387 reasons to believe that the stranger told the truth. 58 00:05:10,387 --> 00:05:15,227 But the point I'm making right now is that these two premises can't be a good 59 00:05:15,227 --> 00:05:20,780 reason to believe that the stranger told the truth, if your reason for believing 60 00:05:20,780 --> 00:05:25,816 the second premise is just that the stranger said that the street was three 61 00:05:25,816 --> 00:05:29,721 blocks north of here. Now why is that? Why can't these two 62 00:05:29,721 --> 00:05:35,177 premises be a good reason for you to believe that the stranger told the truth? 63 00:05:35,177 --> 00:05:40,924 In the situation in which your reason for believing the second premise is just the 64 00:05:40,924 --> 00:05:43,967 truth of the first premise. Here's why. 65 00:05:43,967 --> 00:05:49,344 Suppose the stranger tells you that the street is three blocks north of there. 66 00:05:49,344 --> 00:05:54,557 Well, why should you believe that the street is really three blocks north of 67 00:05:54,557 --> 00:05:58,137 there? Well, you should believe it, just in case 68 00:05:58,137 --> 00:06:03,802 you have a good reason to believe already that the stranger told the truth. 69 00:06:03,802 --> 00:06:09,204 In other words, if you don't already have a good reason to believe that the 70 00:06:09,204 --> 00:06:14,852 stranger told the truth, then you're not going to have a reason to believe the 71 00:06:14,852 --> 00:06:20,557 second premise of this argument on the basis of the fact that the stranger said 72 00:06:20,557 --> 00:06:23,622 that the street was three blocks north of there. 73 00:06:24,644 --> 00:06:30,465 Right? The stranger might have said it, but so what? If you don't have any reason 74 00:06:30,465 --> 00:06:33,687 to believe that the stranger told the truth. 75 00:06:33,687 --> 00:06:39,564 So, if you have a good reason to believe the second premise of this argument, that 76 00:06:39,564 --> 00:06:42,811 the street really is three blocks north of there, 77 00:06:42,811 --> 00:06:48,569 and your good reason has to do with the fact that the stranger said that the 78 00:06:48,569 --> 00:06:54,104 street was three blocks north of there, then that shows that you already have 79 00:06:54,104 --> 00:06:58,421 some reason to believe that the stranger told the truth. 80 00:06:58,421 --> 00:07:03,981 So, if you go and draw the conclussion, the stranger told the truth, that 81 00:07:03,981 --> 00:07:10,308 conclusion, is something that you must of already had a reason to believe. 82 00:07:10,308 --> 00:07:16,802 So this argument can't give you anymore reason to believe it than you already 83 00:07:16,802 --> 00:07:20,483 had. So that's why this argument can't give 84 00:07:20,483 --> 00:07:27,027 you a reason to believe its conclusion even in the case, where the argument is 85 00:07:27,027 --> 00:07:30,905 sound. It might be sound but it's still 86 00:07:30,905 --> 00:07:35,035 ineffective. And this particular kind of 87 00:07:35,035 --> 00:07:42,115 ineffectiveness is one example of what I'll call begging the question. 88 00:07:42,115 --> 00:07:49,902 The argument doesn't make any progress because in order to draw the conclusion 89 00:07:49,902 --> 00:07:54,233 You already have to be justified in believing the conclusion. 90 00:07:54,233 --> 00:07:59,469 In short, you don't learn anything from the argument, you can only draw the 91 00:07:59,469 --> 00:08:04,630 conclusion if you had a good reason for believing the conclusion already. 92 00:08:04,630 --> 00:08:09,272 Now as I said, that example of begging the question is so obvious, 93 00:08:09,272 --> 00:08:13,608 I doubt any of you would be guilty of it or would fall for it. 94 00:08:13,608 --> 00:08:19,534 But let's consider an example of begging the question that's close to something I 95 00:08:19,534 --> 00:08:24,426 actually heard on American television just a couple of months ago. 96 00:08:24,426 --> 00:08:29,567 A friend of American Presidential candidate Mitt Romney said in an 97 00:08:29,567 --> 00:08:37,372 interview that Mitt Romney was going to win the American presidential election. 98 00:08:37,372 --> 00:08:43,992 And his reasoning was that since Mitt Romney never fails in any of his 99 00:08:43,992 --> 00:08:51,220 projects, and since one of his biggest projects ever was to win the American 100 00:08:51,220 --> 00:08:57,669 presidential election, Romney was going to win the American presidential 101 00:08:57,669 --> 00:09:02,304 election. Now consider that argument, that argument 102 00:09:02,304 --> 00:09:08,361 actully was offered by some prominent person on American television. 103 00:09:08,361 --> 00:09:15,608 Premise one. [SOUND] Mitt Romney [SOUND] never fails 104 00:09:15,608 --> 00:09:28,212 [SOUND] in his projects. [SOUND] Premise 2, [SOUND] Romney's 105 00:09:28,212 --> 00:09:45,319 running for President. Conclusion, 106 00:09:45,319 --> 00:09:45,319 [SOUND] 107 00:09:45,319 --> 00:10:00,996 Romney will win [SOUND] the presidency. Now, once again, notice this argument is 108 00:10:00,996 --> 00:10:07,117 valid. If both of the premises are true, then 109 00:10:07,117 --> 00:10:14,730 the conclusion has to be true. Right, if it is indeed one of Romney's 110 00:10:14,730 --> 00:10:21,722 projects to win the presidency, and if indeed he never fails in his projects, 111 00:10:21,722 --> 00:10:26,991 then he will win the presidency. So the argument is valid. 112 00:10:26,991 --> 00:10:34,082 But, is it guilty of a fallacy of acuity? Well, in this particular case, yes. 113 00:10:34,082 --> 00:10:39,472 It begs the question and the reason it begs the question is because whatever 114 00:10:39,472 --> 00:10:45,022 reason you have for believing the first premise of the argument, Romney never 115 00:10:45,022 --> 00:10:49,457 fails in his projects. Whatever reason you have for believing 116 00:10:49,457 --> 00:10:55,136 that must include some reason you have for believing the conclusion that Romney 117 00:10:55,136 --> 00:10:59,414 will win the Presidency. Unless you already have a reason for 118 00:10:59,414 --> 00:11:04,678 believing that Romney will win the Presidency, you can't have a good reason 119 00:11:04,678 --> 00:11:10,201 for believing the first premise of the argument, that Romney never fails in his 120 00:11:10,201 --> 00:11:13,867 projects. So, even though this argument is valid if 121 00:11:13,867 --> 00:11:19,217 there's no possible way for the premeses to be true and the conclusion is false, 122 00:11:19,217 --> 00:11:24,567 nonetheless, the argument does beg the question and so is guilty of a fallacy of 123 00:11:24,567 --> 00:11:27,692 acuity. We've considered a couple examples of 124 00:11:27,692 --> 00:11:31,017 begging the question, but consider yet one more. 125 00:11:31,017 --> 00:11:38,976 Suppose I tell you That God laid down all of his divine commandments in this 126 00:11:38,976 --> 00:11:45,466 pamphlet right here. And you ask me why I believe that. 127 00:11:45,466 --> 00:11:53,951 And I say, well, because the pamphlet. Says that God laid down all of his divine 128 00:11:53,951 --> 00:12:01,587 commandments in this pamphlet right here. And of course, God would not have laid 129 00:12:01,587 --> 00:12:08,043 down his divine commandments in a pamphlet that wasn't wholly true. 130 00:12:08,043 --> 00:12:15,247 So, this pamphlet right here must be wholly true and so must be true, that God 131 00:12:15,247 --> 00:12:20,502 laid down all of his divine commandments in this pamphlet right here. 132 00:12:20,502 --> 00:12:26,012 Now that's an example of begging the question, that is simultaneously an 133 00:12:26,012 --> 00:12:30,657 appeal to authority. That particular argument suffers from 134 00:12:30,657 --> 00:12:36,132 both of the two fallacies that we've described in this lecture and the last. 135 00:12:36,132 --> 00:12:42,529 It is an unjustified appeal to authority, and it begs the question, and I want you 136 00:12:42,529 --> 00:12:48,926 to consider in the exercises that follow which arguments suffer from that same 137 00:12:48,926 --> 00:12:50,737 combination of faults.