00:00 00:01 SPEAKER 1: Since arguments are at the heart of logic 00:03 and argumentation, it's natural to start with this question. 00:07 The first thing to say about arguments 00:08 is that as this term is used in logic, 00:11 it isn't intended to imply anything 00:13 like an emotional confrontation. 00:15 Like when I say that an argument broke out at a bar, 00:17 or I just had a huge argument with my parents 00:20 about my grades or something. 00:22 In logic, an argument is a technical term. 00:25 It doesn't carry any connotation about conflict 00:28 or confrontation. 00:30 So here's our definition. 00:32 It'll have the three parts. 00:34 First part, an argument is a set of claims or statements. 00:39 We'll have more to say about what a claim or statement is 00:41 later, but for now, it's enough to say 00:43 that a claim is the sort of thing that 00:45 can be true or false. 00:48 Next part, one of the claims is singled out 00:51 for special attention. 00:52 We call it a conclusion. 00:54 The remaining claims are called premises. 00:58 And finally, the premises are interpreted as offering reasons 01:03 to believe or accept the conclusion. 01:06 That's it. 01:07 That's the definition of an argument. 01:09 Now let's have a look at one. 01:13 All musicians can read music. 01:15 John is a musician. 01:16 Therefore, John can read music. 01:19 These are the premises, and this is the conclusion. 01:23 Premises one and two are being offered as reason 01:25 to accept the conclusion that John can read music. 01:29 This may not be a particularly good argument, actually, 01:31 since that first premise makes a pretty broad generalization 01:35 about all musicians that isn't very plausible, I don't think. 01:38 I'm sure there are a few great musicians out there that 01:40 don't read sheet music, but it's an argument nonetheless. 01:45 Now, notice how it's been written. 01:49 The premises are each numbered and put on separate lines, 01:51 and the conclusion is placed at the bottom 01:53 and set off from the rest by a line and flagged with the word 01:56 therefore. 01:58 This is called putting an argument in standard form, 02:02 and it could be useful when you're doing argument analysis. 02:06 In ordinary language, we almost never are this formal, 02:09 but when you're trying to analyze arguments, when you're 02:11 investigating your logical properties, 02:13 or considering whether the premises are true or not, 02:16 putting an argument in standard form 02:18 can make life a lot easier. 02:20 And just to highlight this point, 02:21 here's another way of saying the same thing. 02:25 Can John read music? 02:26 Of course. 02:26 He's a musician, isn't he? 02:29 These actually express the very same argument, 02:33 but notice how much easier it is to see 02:36 the structure of the argument when 02:38 it's written in standard form. 02:40 In the second version in yellow here, you 02:42 have to infer the conclusion John can read music 02:45 from the opening question and the of course part, 02:50 and you have to fill in an assumed premise. 02:52 What you're given is Jon is a musician, 02:56 but the conclusion only follows. 02:58 If you assume that all musicians, or most musicians, 03:02 can read music, which is not given. 03:04 It's just a background assumption. 03:07 The argument only makes sense because you're 03:08 filling in the background premise automatically, 03:11 but you can imagine that this might become 03:13 a problem for more complex arguments 03:15 where you can't always be sure that everyone is filling 03:17 in the same background premise. 03:20 So the standard form can be helpful, 03:23 and we're going to be using it a lot in this course. 03:27 Here are the takeaway points to remember from this. 03:31 First, an argument is just a set of claims 03:34 that are offered as reasons to believe or accept 03:37 another claim. 03:39 Second, we saw that the same argument can 03:41 be written in more than one way, and in general it's 03:44 true that the same argument can be written or expressed 03:47 in many different ways using different words, 03:50 different sentences, and different sentence structure. 03:54 Now, because of this, it is often 03:56 helpful to put arguments in standard form 03:59 where you can clearly identify which parts of the argument 04:02 are functioning as the premises and which 04:04 part is the conclusion. 04:06 And you make all the premises and background assumptions 04:08 explicit by writing them on separate lines. 04:12 Being able to do this is actually 04:14 an important skill in logic. 04:16