WEBVTT 00:00:01.624 --> 00:00:03.790 SPEAKER 1: Since arguments are at the heart of logic 00:00:03.790 --> 00:00:07.177 and argumentation, it's natural to start with this question. 00:00:07.177 --> 00:00:08.760 The first thing to say about arguments 00:00:08.760 --> 00:00:11.000 is that as this term is used in logic, 00:00:11.000 --> 00:00:13.260 it isn't intended to imply anything 00:00:13.260 --> 00:00:15.070 like an emotional confrontation. 00:00:15.070 --> 00:00:17.700 Like when I say that an argument broke out at a bar, 00:00:17.700 --> 00:00:20.105 or I just had a huge argument with my parents 00:00:20.105 --> 00:00:22.520 about my grades or something. 00:00:22.520 --> 00:00:25.465 In logic, an argument is a technical term. 00:00:25.465 --> 00:00:28.170 It doesn't carry any connotation about conflict 00:00:28.170 --> 00:00:30.840 or confrontation. 00:00:30.840 --> 00:00:32.119 So here's our definition. 00:00:32.119 --> 00:00:34.540 It'll have the three parts. 00:00:34.540 --> 00:00:39.145 First part, an argument is a set of claims or statements. 00:00:39.145 --> 00:00:41.520 We'll have more to say about what a claim or statement is 00:00:41.520 --> 00:00:43.630 later, but for now, it's enough to say 00:00:43.630 --> 00:00:45.400 that a claim is the sort of thing that 00:00:45.400 --> 00:00:48.470 can be true or false. 00:00:48.470 --> 00:00:51.150 Next part, one of the claims is singled out 00:00:51.150 --> 00:00:52.220 for special attention. 00:00:52.220 --> 00:00:54.325 We call it a conclusion. 00:00:54.325 --> 00:00:58.090 The remaining claims are called premises. 00:00:58.090 --> 00:01:03.350 And finally, the premises are interpreted as offering reasons 00:01:03.350 --> 00:01:06.770 to believe or accept the conclusion. 00:01:06.770 --> 00:01:07.620 That's it. 00:01:07.620 --> 00:01:09.950 That's the definition of an argument. 00:01:09.950 --> 00:01:13.080 Now let's have a look at one. 00:01:13.080 --> 00:01:15.060 All musicians can read music. 00:01:15.060 --> 00:01:16.070 John is a musician. 00:01:16.070 --> 00:01:19.350 Therefore, John can read music. 00:01:19.350 --> 00:01:23.130 These are the premises, and this is the conclusion. 00:01:23.130 --> 00:01:25.130 Premises one and two are being offered as reason 00:01:25.130 --> 00:01:29.199 to accept the conclusion that John can read music. 00:01:29.199 --> 00:01:31.490 This may not be a particularly good argument, actually, 00:01:31.490 --> 00:01:35.290 since that first premise makes a pretty broad generalization 00:01:35.290 --> 00:01:38.199 about all musicians that isn't very plausible, I don't think. 00:01:38.199 --> 00:01:40.490 I'm sure there are a few great musicians out there that 00:01:40.490 --> 00:01:45.930 don't read sheet music, but it's an argument nonetheless. 00:01:45.930 --> 00:01:49.070 Now, notice how it's been written. 00:01:49.070 --> 00:01:51.550 The premises are each numbered and put on separate lines, 00:01:51.550 --> 00:01:53.300 and the conclusion is placed at the bottom 00:01:53.300 --> 00:01:56.770 and set off from the rest by a line and flagged with the word 00:01:56.770 --> 00:01:58.260 therefore. 00:01:58.260 --> 00:02:02.830 This is called putting an argument in standard form, 00:02:02.830 --> 00:02:06.500 and it could be useful when you're doing argument analysis. 00:02:06.500 --> 00:02:09.007 In ordinary language, we almost never are this formal, 00:02:09.007 --> 00:02:11.340 but when you're trying to analyze arguments, when you're 00:02:11.340 --> 00:02:13.510 investigating your logical properties, 00:02:13.510 --> 00:02:16.501 or considering whether the premises are true or not, 00:02:16.501 --> 00:02:18.000 putting an argument in standard form 00:02:18.000 --> 00:02:20.016 can make life a lot easier. 00:02:20.016 --> 00:02:21.450 And just to highlight this point, 00:02:21.450 --> 00:02:25.180 here's another way of saying the same thing. 00:02:25.180 --> 00:02:26.140 Can John read music? 00:02:26.140 --> 00:02:26.800 Of course. 00:02:26.800 --> 00:02:29.600 He's a musician, isn't he? 00:02:29.600 --> 00:02:33.850 These actually express the very same argument, 00:02:33.850 --> 00:02:36.300 but notice how much easier it is to see 00:02:36.300 --> 00:02:38.050 the structure of the argument when 00:02:38.050 --> 00:02:40.620 it's written in standard form. 00:02:40.620 --> 00:02:42.430 In the second version in yellow here, you 00:02:42.430 --> 00:02:45.840 have to infer the conclusion John can read music 00:02:45.840 --> 00:02:50.170 from the opening question and the of course part, 00:02:50.170 --> 00:02:52.240 and you have to fill in an assumed premise. 00:02:52.240 --> 00:02:56.060 What you're given is Jon is a musician, 00:02:56.060 --> 00:02:58.490 but the conclusion only follows. 00:02:58.490 --> 00:03:02.130 If you assume that all musicians, or most musicians, 00:03:02.130 --> 00:03:04.650 can read music, which is not given. 00:03:04.650 --> 00:03:07.127 It's just a background assumption. 00:03:07.127 --> 00:03:08.960 The argument only makes sense because you're 00:03:08.960 --> 00:03:11.520 filling in the background premise automatically, 00:03:11.520 --> 00:03:13.270 but you can imagine that this might become 00:03:13.270 --> 00:03:15.180 a problem for more complex arguments 00:03:15.180 --> 00:03:17.810 where you can't always be sure that everyone is filling 00:03:17.810 --> 00:03:20.540 in the same background premise. 00:03:20.540 --> 00:03:23.840 So the standard form can be helpful, 00:03:23.840 --> 00:03:27.580 and we're going to be using it a lot in this course. 00:03:27.580 --> 00:03:31.250 Here are the takeaway points to remember from this. 00:03:31.250 --> 00:03:34.640 First, an argument is just a set of claims 00:03:34.640 --> 00:03:37.090 that are offered as reasons to believe or accept 00:03:37.090 --> 00:03:39.360 another claim. 00:03:39.360 --> 00:03:41.990 Second, we saw that the same argument can 00:03:41.990 --> 00:03:44.640 be written in more than one way, and in general it's 00:03:44.640 --> 00:03:47.240 true that the same argument can be written or expressed 00:03:47.240 --> 00:03:50.370 in many different ways using different words, 00:03:50.370 --> 00:03:54.190 different sentences, and different sentence structure. 00:03:54.190 --> 00:03:56.590 Now, because of this, it is often 00:03:56.590 --> 00:03:59.620 helpful to put arguments in standard form 00:03:59.620 --> 00:04:02.420 where you can clearly identify which parts of the argument 00:04:02.420 --> 00:04:04.420 are functioning as the premises and which 00:04:04.420 --> 00:04:06.547 part is the conclusion. 00:04:06.547 --> 00:04:08.880 And you make all the premises and background assumptions 00:04:08.880 --> 00:04:12.320 explicit by writing them on separate lines. 00:04:12.320 --> 00:04:14.260 Being able to do this is actually 00:04:14.260 --> 00:04:16.730 an important skill in logic.