[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:02.56,0:00:10.66,Default,,0000,0000,0000,,It's been a long and winding road as the\NBeatles used to say, but we're finally at
Dialogue: 0,0:00:10.66,0:00:17.27,Default,,0000,0000,0000,,the last stages of reconstructing\Narguments. We've looked at stage one,
Dialogue: 0,0:00:17.27,0:00:24.24,Default,,0000,0000,0000,,which is close analysis. Stage two which\Nis get down to basics. Stage three which
Dialogue: 0,0:00:24.24,0:00:31.22,Default,,0000,0000,0000,,is sharpen edges, stage four is organize\Nparts, and we are doing stage five which
Dialogue: 0,0:00:31.22,0:00:37.65,Default,,0000,0000,0000,,is fill in gaps and we'll also get to\Nstage six which is conclude. Stage five
Dialogue: 0,0:00:37.65,0:00:42.61,Default,,0000,0000,0000,,really consists of four separate steps.\NFirst we need to assess the argument for
Dialogue: 0,0:00:42.61,0:00:47.63,Default,,0000,0000,0000,,validity. Then we need to add suppressed\Npremises. Enough of them to make it valid.
Dialogue: 0,0:00:47.63,0:00:52.69,Default,,0000,0000,0000,,Then we need to assess those suppressed\Npremises for truth or falsehood. And then
Dialogue: 0,0:00:52.69,0:00:58.39,Default,,0000,0000,0000,,we need to qualify the suppressed premises\Nin order to make them true. The whole goal
Dialogue: 0,0:00:58.39,0:01:03.75,Default,,0000,0000,0000,,is to make the suppressed premises both\Nplausible for their truth, and enough to
Dialogue: 0,0:01:03.75,0:01:09.18,Default,,0000,0000,0000,,make the argument valid. So, these steps\Nwithin the stage really do work in tandem
Dialogue: 0,0:01:09.18,0:01:14.28,Default,,0000,0000,0000,,together to try and make the argument\Ngood. We already learned how to assess
Dialogue: 0,0:01:14.28,0:01:18.87,Default,,0000,0000,0000,,validity. You simply ask, "Is it possible\Nfor the premises to be true and the
Dialogue: 0,0:01:18.87,0:01:23.72,Default,,0000,0000,0000,,conclusion false, and if so, the argument\Nis not valid and if not, the argument is
Dialogue: 0,0:01:23.72,0:01:28.68,Default,,0000,0000,0000,,valid." And the way you figure out whether\Nit's possible is you try to tell a story
Dialogue: 0,0:01:28.68,0:01:33.46,Default,,0000,0000,0000,,or describe a situation and if you can\Ndescribe a coherent situation where the
Dialogue: 0,0:01:33.46,0:01:38.42,Default,,0000,0000,0000,,premises are true and the conclusion is\Nfalse, then that show that the argument is
Dialogue: 0,0:01:38.42,0:01:43.26,Default,,0000,0000,0000,,not really valid. The main topic for today\Nis, what do you do when you assess the
Dialogue: 0,0:01:43.26,0:01:48.14,Default,,0000,0000,0000,,argument for validity and you find out\Nit's not valid?" And the answer is, you
Dialogue: 0,0:01:48.14,0:01:53.93,Default,,0000,0000,0000,,add suppressed premises, enough of them to\Nmake the argument valid. But that might
Dialogue: 0,0:01:53.93,0:01:58.87,Default,,0000,0000,0000,,seem like cheating. I mean, you start with\Nan argument that's no good, it's not
Dialogue: 0,0:01:58.87,0:02:03.82,Default,,0000,0000,0000,,valid, and then you just throw in some\Nextra premises in order to make it valid.
Dialogue: 0,0:02:03.82,0:02:08.75,Default,,0000,0000,0000,,Why is it that's just distorting the\Nargument and making up something that
Dialogue: 0,0:02:08.75,0:02:14.01,Default,,0000,0000,0000,,wasn't there? The answer is that it's not\Nreally bad. And if it were bad, we'd all
Dialogue: 0,0:02:14.01,0:02:19.21,Default,,0000,0000,0000,,be in bad shape because in everyday life,\Npeople always take things for granted.
Dialogue: 0,0:02:19.21,0:02:24.41,Default,,0000,0000,0000,,They make assumptions. We do it too, and\Nif we didn't, boy, our arguments would be
Dialogue: 0,0:02:24.41,0:02:28.81,Default,,0000,0000,0000,,really long and boring. So there's\Nsomething to be said in favor of
Dialogue: 0,0:02:28.81,0:02:33.68,Default,,0000,0000,0000,,suppressing premises, at least, the\Nobvious ones that people really do take
Dialogue: 0,0:02:33.68,0:02:39.52,Default,,0000,0000,0000,,for granted. But we can also get tricked.\NPeople can suppress premises that really
Dialogue: 0,0:02:39.52,0:02:45.16,Default,,0000,0000,0000,,are questionable, and they just don't want\Nus to see that they're making that
Dialogue: 0,0:02:45.16,0:02:50.62,Default,,0000,0000,0000,,assumption. So, it's useful to fill out\Nthe argument with suppressed premises to
Dialogue: 0,0:02:50.62,0:02:55.76,Default,,0000,0000,0000,,make sure it really is valid, because that\Nbrings those assumptions out in the open,
Dialogue: 0,0:02:55.76,0:03:00.90,Default,,0000,0000,0000,,where we can assess whether or not they're\Ntrue or false. Another reason to fill in
Dialogue: 0,0:03:00.90,0:03:05.58,Default,,0000,0000,0000,,suppressed premises is to understand the\Nargument better. Because if people
Dialogue: 0,0:03:05.58,0:03:10.80,Default,,0000,0000,0000,,suppress premises, then they're showing us\Nsome of their footprints along the path.
Dialogue: 0,0:03:10.80,0:03:15.89,Default,,0000,0000,0000,,But if we really want to know the full\Npath that their reasoning followed, we've
Dialogue: 0,0:03:15.89,0:03:20.68,Default,,0000,0000,0000,,got to see every single footprint. So, the\Ngoal of bringing up the suppressed
Dialogue: 0,0:03:20.68,0:03:25.93,Default,,0000,0000,0000,,premises is to let us trace exactly where\Nthe reasoning is from one step to another.
Dialogue: 0,0:03:25.93,0:03:30.80,Default,,0000,0000,0000,,So there are two goals: One is to trace\Nthe full path every step and the other
Dialogue: 0,0:03:30.80,0:03:36.04,Default,,0000,0000,0000,,goal is to see if there are any miss-steps\Nor they are trying to hid something from
Dialogue: 0,0:03:36.04,0:03:40.78,Default,,0000,0000,0000,,us by getting rid of one of their\Nfootsteps, so that's the point of bringing
Dialogue: 0,0:03:40.78,0:03:45.90,Default,,0000,0000,0000,,up suppressed premises. To accomplish\Nthese goals is tricky. You have to find
Dialogue: 0,0:03:45.90,0:03:51.22,Default,,0000,0000,0000,,suppressed premises that are just strong\Nenough to make the argument valid but not
Dialogue: 0,0:03:51.22,0:03:56.55,Default,,0000,0000,0000,,so strong that there gonna be implausible.\NCuz you don't wanna ascribe all kinds of
Dialogue: 0,0:03:56.55,0:04:01.36,Default,,0000,0000,0000,,suppressed premises to the person that\Nthey didn't really believe, and they
Dialogue: 0,0:04:01.36,0:04:06.75,Default,,0000,0000,0000,,didn't really need for their argument. So\Nit's kind of like Goldilocks and the Three
Dialogue: 0,0:04:06.75,0:04:11.82,Default,,0000,0000,0000,,Bears. You want suppressed premises to be\Nnot too hot and not too cold, but just
Dialogue: 0,0:04:11.82,0:04:17.75,Default,,0000,0000,0000,,right. Here's an example from a previous\Nlecture. My wife always gives me either a
Dialogue: 0,0:04:17.75,0:04:24.16,Default,,0000,0000,0000,,sweater or a board game. This box does not\Ncontain a sweater because it rattles when
Dialogue: 0,0:04:24.16,0:04:29.95,Default,,0000,0000,0000,,it's shaken so this time she must have\Ngiven me a board game. We put this in
Dialogue: 0,0:04:29.95,0:04:35.97,Default,,0000,0000,0000,,standard form this way. First premise:\NThis box rattles wh en I shake it and that
Dialogue: 0,0:04:35.97,0:04:42.85,Default,,0000,0000,0000,,shows you it doesn't contain a sweater.\NThird, she always gives me either a
Dialogue: 0,0:04:42.85,0:04:49.18,Default,,0000,0000,0000,,sweater or a board game. Conclusion, this\Ntime she must have given me a board game.
Dialogue: 0,0:04:50.22,0:04:56.58,Default,,0000,0000,0000,,Now the first step in this argument is,\Nthis box rattles when I shake it. And the
Dialogue: 0,0:04:56.58,0:05:02.65,Default,,0000,0000,0000,,conclusion there is it doesn't contain a\Nsweater. That's the part of the argument
Dialogue: 0,0:05:02.65,0:05:08.64,Default,,0000,0000,0000,,we want to focus on here and ask whether\Nthat argument is valid. The argument is
Dialogue: 0,0:05:08.64,0:05:14.48,Default,,0000,0000,0000,,not valid, because it's possible for the\Npremise to be true and the conclusion
Dialogue: 0,0:05:14.48,0:05:19.67,Default,,0000,0000,0000,,false. How can that happen? Well, my wife\Nmight be fooling me. She might know that I
Dialogue: 0,0:05:19.67,0:05:24.86,Default,,0000,0000,0000,,expect either a sweater or a board game,\Nso she puts a sweater in the box. And then
Dialogue: 0,0:05:24.86,0:05:29.92,Default,,0000,0000,0000,,she puts little rocks around the outside\Nso when I shake it, I'll hear something.
Dialogue: 0,0:05:29.92,0:05:35.04,Default,,0000,0000,0000,,So that's possible, and that shows that\Nthe argument's not valid. Well, how can we
Dialogue: 0,0:05:35.04,0:05:40.53,Default,,0000,0000,0000,,make the argument valid? The question here\Nis, can we add a suppressed premise that
Dialogue: 0,0:05:40.53,0:05:45.75,Default,,0000,0000,0000,,will turn this invalid argument into a\Nvalid argument? Here's one that will do
Dialogue: 0,0:05:45.75,0:05:51.79,Default,,0000,0000,0000,,the trick. A box that contains a sweater\Ndoesn't rattle when shaken. Now the
Dialogue: 0,0:05:51.79,0:05:57.56,Default,,0000,0000,0000,,argument looks like this. This box rattles\Nwhen I shake it. The box that contains a
Dialogue: 0,0:05:57.56,0:06:02.97,Default,,0000,0000,0000,,sweater doesn't rattle when shaken, so\Nthis box doesn't contain a sweater. The
Dialogue: 0,0:06:02.97,0:06:08.87,Default,,0000,0000,0000,,explicit premise is that this box rattles\Nwhen I shake it. The suppressed premise is
Dialogue: 0,0:06:08.87,0:06:14.78,Default,,0000,0000,0000,,that a box that contains a sweater doesn't\Nrattle when shaken and together they are
Dialogue: 0,0:06:14.78,0:06:20.61,Default,,0000,0000,0000,,suppose support the conclusion that this\Nbox doesn't contain a sweater, but do they
Dialogue: 0,0:06:20.61,0:06:26.52,Default,,0000,0000,0000,,really support that conclusion? Is the\Nargument valid? Well, it's valid only if
Dialogue: 0,0:06:26.52,0:06:31.28,Default,,0000,0000,0000,,there's no possibility that the premises\Nare true and the conclusions false.
Dialogue: 0,0:06:31.28,0:06:36.47,Default,,0000,0000,0000,,Without the suppressed premise we saw this\Nmight be possible, because my wife might
Dialogue: 0,0:06:36.47,0:06:41.10,Default,,0000,0000,0000,,be fooling me and putting rocks around the\Nsweater. So let's see if that's going to
Dialogue: 0,0:06:41.47,0:06:45.97,Default,,0000,0000,0000,,ruin the validity of this argument. No!\NBecause if the sweater has got rocks
Dialogue: 0,0:06:45.97,0:06:51.09,Default,,0000,0000,0000,,around it so it makes noise when I shake\Nit, then the premise that says a box that
Dialogue: 0,0:06:51.09,0:06:55.33,Default,,0000,0000,0000,,contains a sweater doesn't rattle when\Nshaken turns out to be fal se.
Dialogue: 0,0:06:55.34,0:07:00.64,Default,,0000,0000,0000,,So that's not a case where the premises\Nare true and the conclusions false because
Dialogue: 0,0:07:00.64,0:07:05.76,Default,,0000,0000,0000,,the premise is false in that case. So, by\Nadding this premise, we actually succeeded
Dialogue: 0,0:07:05.76,0:07:11.87,Default,,0000,0000,0000,,in making the argument valid. The problem\Nof course is that validity is not enough
Dialogue: 0,0:07:11.87,0:07:17.84,Default,,0000,0000,0000,,for a good argument, as we saw several\Nlectures ago. You can have an argument
Dialogue: 0,0:07:17.84,0:07:23.74,Default,,0000,0000,0000,,that's very bad, when the argument is not\Nsound. What we want really is soundness.
Dialogue: 0,0:07:23.74,0:07:29.35,Default,,0000,0000,0000,,So, that's why we need the next step,\Nmainly, check the supressed premises for
Dialogue: 0,0:07:29.35,0:07:34.95,Default,,0000,0000,0000,,truth. Assess whether they're true or\Nfalse. And, if they're not true, then you
Dialogue: 0,0:07:34.95,0:07:40.85,Default,,0000,0000,0000,,need to qualify them, in order to make\Nthem true. Cuz you don't want to claim
Dialogue: 0,0:07:40.85,0:07:46.75,Default,,0000,0000,0000,,that the person giving the argument was\Nassuming this falsehood, when the didn't
Dialogue: 0,0:07:46.75,0:07:52.71,Default,,0000,0000,0000,,have to. So let's see if there's some way\Nto qualify this suppressed premise in
Dialogue: 0,0:07:52.71,0:08:00.04,Default,,0000,0000,0000,,order to make it true. How can we qualify\Nthis premise to make it true? How are we
Dialogue: 0,0:08:00.04,0:08:06.83,Default,,0000,0000,0000,,going to do that? Let me think. Oh. What\Nabout that little word only. You could add
Dialogue: 0,0:08:06.83,0:08:15.02,Default,,0000,0000,0000,,that. You could say, a box that contains\Nonly a sweater doesn't rattle when shaken.
Dialogue: 0,0:08:15.62,0:08:20.92,Default,,0000,0000,0000,,But the word only, what exactly does that\Nmean? We need to clarify that. What
Dialogue: 0,0:08:20.92,0:08:26.43,Default,,0000,0000,0000,,exactly is the word only exclude? It\Nexcludes something, that's the function of
Dialogue: 0,0:08:26.43,0:08:32.68,Default,,0000,0000,0000,,the word only, but what does it exclude?\NWell. It probably excludes other things
Dialogue: 0,0:08:32.68,0:08:38.92,Default,,0000,0000,0000,,that might make the rattling sound like if\Nmy wife put rocks in the box. So we can
Dialogue: 0,0:08:38.92,0:08:45.23,Default,,0000,0000,0000,,clarify this premise by saying a box that\Ncontains only a sweater and not anything
Dialogue: 0,0:08:45.23,0:08:51.52,Default,,0000,0000,0000,,else that might make a rattling sound when\Nshaken, won't rattle when shaken. Well, is
Dialogue: 0,0:08:51.52,0:08:57.54,Default,,0000,0000,0000,,that premise true? Well, you might quibble\Nabout details but it's close enough for
Dialogue: 0,0:08:57.54,0:09:03.33,Default,,0000,0000,0000,,now. What we need to do though is to go\Nback and determine whether, when we put
Dialogue: 0,0:09:03.33,0:09:09.27,Default,,0000,0000,0000,,that suppressed premise in, the argument's\Nvalid. And the argument now looks like
Dialogue: 0,0:09:09.27,0:09:15.28,Default,,0000,0000,0000,,this. This box does rattle when shaken,\Nand a box doesn't rattle when shaken if it
Dialogue: 0,0:09:15.28,0:09:21.77,Default,,0000,0000,0000,,contains only a sweater and not anything\Nelse that makes a rattling sound. So this
Dialogue: 0,0:09:21.77,0:09:29.49,Default,,0000,0000,0000,,box doesn't contain a sweater. Is that\Nvalid? Well, no, for the same reason we s
Dialogue: 0,0:09:29.49,0:09:35.46,Default,,0000,0000,0000,,aw before, because my wife might be a\Ntrickster who puts rocks around my sweater
Dialogue: 0,0:09:35.46,0:09:41.58,Default,,0000,0000,0000,,in the birthday present box in order to\Nfool me. Then, the premises can be true,
Dialogue: 0,0:09:41.58,0:09:48.40,Default,,0000,0000,0000,,and the conclusion false. It's possible\Nthat, the first premise is true. This box
Dialogue: 0,0:09:48.40,0:09:54.91,Default,,0000,0000,0000,,rattles when I shake it. And the second\Npremise is true, a box doesn't rattle when
Dialogue: 0,0:09:54.91,0:10:00.45,Default,,0000,0000,0000,,shaken if it contains only a sweater and\Nnothing else that makes a rattling sound.
Dialogue: 0,0:10:00.45,0:10:04.80,Default,,0000,0000,0000,,But it's false that this box doesn't\Ncontain a sweater, cuz it still does
Dialogue: 0,0:10:04.80,0:10:09.45,Default,,0000,0000,0000,,contain a sweater, and it contains a\Nsweater in addition to those pesky little
Dialogue: 0,0:10:09.45,0:10:13.74,Default,,0000,0000,0000,,rocks that make all that rattling noise.\NWell, if your argument's not valid, we've
Dialogue: 0,0:10:13.74,0:10:18.04,Default,,0000,0000,0000,,got to go back to that other step and add\Nanother suppressed premise. Remember how I
Dialogue: 0,0:10:18.04,0:10:22.28,Default,,0000,0000,0000,,told you how these different steps within\Nthis stage work in tandem and what's
Dialogue: 0,0:10:22.28,0:10:25.90,Default,,0000,0000,0000,,happening is you've got to check it for\Nvalidity, add a suppressed premise,
Dialogue: 0,0:10:25.90,0:10:30.04,Default,,0000,0000,0000,,recheck for validity, maybe add another\Nsuppressed premise, and that's what we're
Dialogue: 0,0:10:30.04,0:10:35.23,Default,,0000,0000,0000,,doing now. So what kind of suppressed\Npremised can we add. Well, we could add my
Dialogue: 0,0:10:35.23,0:10:40.87,Default,,0000,0000,0000,,wife is not a trickster but basically that\Namounts to she wouldn't put rocks in a
Dialogue: 0,0:10:40.87,0:10:46.57,Default,,0000,0000,0000,,birthday present with a sweater in order\Nto fool me. So we could make that a little
Dialogue: 0,0:10:46.57,0:10:52.00,Default,,0000,0000,0000,,more explicit by making the suppressed\Npremise something like this. If this box
Dialogue: 0,0:10:52.00,0:10:57.70,Default,,0000,0000,0000,,contains a sweater, then it only contains\Na sweater and it doesn't include anything
Dialogue: 0,0:10:57.70,0:11:03.38,Default,,0000,0000,0000,,else that would make a rattling sound when\Nshaken. And now we can stick that as an
Dialogue: 0,0:11:03.38,0:11:08.37,Default,,0000,0000,0000,,extra suppressed premise into the\Nargument. Now the argument looks like
Dialogue: 0,0:11:08.37,0:11:14.85,Default,,0000,0000,0000,,this. This box rattles when I shake it. A\Nbox doesn't rattle when shaken, if it
Dialogue: 0,0:11:14.85,0:11:20.98,Default,,0000,0000,0000,,contains only a sweater and not anything\Nelse that makes a rattling noise when
Dialogue: 0,0:11:20.98,0:11:27.63,Default,,0000,0000,0000,,shaken. If this box contains a sweater,\Nthen it contains only a sweater and
Dialogue: 0,0:11:27.63,0:11:34.38,Default,,0000,0000,0000,,doesn't contain anything that rattles when\Nshaken. So this box does not contain a
Dialogue: 0,0:11:34.38,0:11:39.78,Default,,0000,0000,0000,,sweater. Now we have an argument that's\Nvalid. And the suppressed premises are
Dialogue: 0,0:11:39.78,0:11:44.98,Default,,0000,0000,0000,,true, at least given our life's not a\Ntrickster, which she's not, I assure you.
Dialogue: 0,0:11:44.98,0:11:51.00,Default,,0000,0000,0000,,And it looks like we have a sound rec\Nonstruction, just what we were looking
Dialogue: 0,0:11:51.00,0:11:56.35,Default,,0000,0000,0000,,for. Admittedly, this argument is a lot\Nlonger and more convoluted than the
Dialogue: 0,0:11:56.35,0:12:01.68,Default,,0000,0000,0000,,original, and that shows why people\Nsuppress premises instead of talking the
Dialogue: 0,0:12:01.68,0:12:06.77,Default,,0000,0000,0000,,way this argument goes. And of course,\Nmany people would be perfectly well
Dialogue: 0,0:12:06.77,0:12:12.75,Default,,0000,0000,0000,,convinced by the original argument because\Nthey share the assumptions that are in the
Dialogue: 0,0:12:12.75,0:12:18.24,Default,,0000,0000,0000,,suppressed premises. So why do we go\Nthrough all the trouble to go through this
Dialogue: 0,0:12:18.24,0:12:22.90,Default,,0000,0000,0000,,process and add the suppressed premises?\NRemember, the reason is that we want to
Dialogue: 0,0:12:23.31,0:12:27.62,Default,,0000,0000,0000,,understand the pathway between the\Npremises and conclusion. We want to
Dialogue: 0,0:12:28.04,0:12:33.23,Default,,0000,0000,0000,,understand how the reasoning works step by\Nstep by step. And we want to do that
Dialogue: 0,0:12:33.23,0:12:37.63,Default,,0000,0000,0000,,because sometimes people are going to\Ninclude suppressed premises that aren't
Dialogue: 0,0:12:37.63,0:12:42.26,Default,,0000,0000,0000,,true, and we want to bring them out and\Nmake those assumptions explicit so that we
Dialogue: 0,0:12:42.26,0:12:46.88,Default,,0000,0000,0000,,can assess them for truth and falsehood.\NAnd when you're talking to somebody you
Dialogue: 0,0:12:46.88,0:12:51.60,Default,,0000,0000,0000,,trust, you might not have to do that and\Nit's okay to suppress premises. But when
Dialogue: 0,0:12:51.60,0:12:56.15,Default,,0000,0000,0000,,you really want to know whether the\Nargument's any good, that's when you want
Dialogue: 0,0:12:56.15,0:13:00.58,Default,,0000,0000,0000,,to fill it out with the suppressed\Npremises. The point of going into detail
Dialogue: 0,0:13:00.58,0:13:04.99,Default,,0000,0000,0000,,on this example is to illustrate this\Nstage of reconstruction. You want to
Dialogue: 0,0:13:04.99,0:13:09.76,Default,,0000,0000,0000,,assess the argument for validity, add\Nsuppressed premises that make it valid.
Dialogue: 0,0:13:09.76,0:13:14.71,Default,,0000,0000,0000,,Check them for truth. If they're not true,\Nyou qualify them, and then you go back and
Dialogue: 0,0:13:14.71,0:13:19.60,Default,,0000,0000,0000,,see whether that qualification made the\Nargument not valid anymore. And you go
Dialogue: 0,0:13:19.60,0:13:24.51,Default,,0000,0000,0000,,back and forth and back and forth until\Nyou've got a sound reconstruction. The
Dialogue: 0,0:13:24.51,0:13:29.81,Default,,0000,0000,0000,,same steps are going to apply to all kinds\Nof suppressed premises. And sure enough,
Dialogue: 0,0:13:29.81,0:13:34.44,Default,,0000,0000,0000,,there are all kinds of suppressed\Npremises. So let's go through a few
Dialogue: 0,0:13:34.44,0:13:39.80,Default,,0000,0000,0000,,examples a lot more quickly in order to\Nshow the variety of suppressed premises
Dialogue: 0,0:13:39.80,0:13:46.78,Default,,0000,0000,0000,,that are assumed in arguments. Here's one\Nexample. Abraham Lincoln turned 40. On
Dialogue: 0,0:13:46.78,0:13:57.96,Default,,0000,0000,0000,,February twelfth, 1849. Therefore, Charles\NDarwin also turned 40 on February twelfth,
Dialogue: 0,0:13:57.96,0:14:04.11,Default,,0000,0000,0000,,1849. Now, is that argument valid? No\Nchance. Of course it's possible for the
Dialogue: 0,0:14:04.11,0:14:09.58,Default,,0000,0000,0000,,premise to be true and the conclus ion\Nfalse. So we have to add a suppressed
Dialogue: 0,0:14:09.58,0:14:15.31,Default,,0000,0000,0000,,premise. The suppressed premise is, that\NAbraham Lincoln and Charles Darwin were
Dialogue: 0,0:14:15.31,0:14:20.64,Default,,0000,0000,0000,,born on the same day. And they were, it\Nhappened to be February twelfth, 1809. So
Dialogue: 0,0:14:20.64,0:14:27.13,Default,,0000,0000,0000,,now, we've filled out the argument.\NAbraham Lincoln turned 40 on February
Dialogue: 0,0:14:27.13,0:14:33.45,Default,,0000,0000,0000,,twelfth, 1849. Abraham Lincoln and Charles\NDarwin were born on the same day,
Dialogue: 0,0:14:33.45,0:14:39.54,Default,,0000,0000,0000,,therefore Charles Darwin also turned 40 on\NFebruary twelfth, 1849. Now is the
Dialogue: 0,0:14:39.54,0:14:46.68,Default,,0000,0000,0000,,argument valid? No. It's still not valid.\NCuz Darwin might have died before 1849. So
Dialogue: 0,0:14:46.68,0:14:53.02,Default,,0000,0000,0000,,we have to add another suppressed premise.\NMainly, that both Abraham Lincoln and
Dialogue: 0,0:14:53.02,0:14:59.66,Default,,0000,0000,0000,,Charles Darwin lived beyond 40. So now we\Nhave a fuller argument. Abraham Lincoln
Dialogue: 0,0:14:59.66,0:15:07.03,Default,,0000,0000,0000,,turned 40 on February twelfth, 1849.\NAbraham Lincoln and Charles Darwin were
Dialogue: 0,0:15:07.03,0:15:14.41,Default,,0000,0000,0000,,born on the same day. Both of them lived\Nbeyond the age of 40. Therefore, Charles
Dialogue: 0,0:15:14.41,0:15:20.100,Default,,0000,0000,0000,,Darwin also turned 40 on February twelve,\N1849. Now the argument looks pretty good.
Dialogue: 0,0:15:20.100,0:15:26.58,Default,,0000,0000,0000,,We had to have two suppressed premises but\Nwe finally have a valid argument. And what
Dialogue: 0,0:15:26.58,0:15:31.30,Default,,0000,0000,0000,,this shows is that sometimes the\Nsuppressed premises are purely factual
Dialogue: 0,0:15:31.30,0:15:36.68,Default,,0000,0000,0000,,matters. In this case that they were born\Non the same day and that they both lived
Dialogue: 0,0:15:36.68,0:15:42.08,Default,,0000,0000,0000,,beyond 40. So sometimes we have factual\Nsuppressed premises. Here's another quick
Dialogue: 0,0:15:42.08,0:15:46.95,Default,,0000,0000,0000,,example. You ought to obey her because\Nshe's your mother. Here, the premise is
Dialogue: 0,0:15:46.95,0:15:52.44,Default,,0000,0000,0000,,that she's your mother and the conclusion\Nis that you ought to obey her. Well, is
Dialogue: 0,0:15:52.44,0:15:57.87,Default,,0000,0000,0000,,that argument valid? No way cause it's\Npossible that she's your mother but it's
Dialogue: 0,0:15:57.87,0:16:03.02,Default,,0000,0000,0000,,false that you ought to obey her. When\Ncould that happen? Maybe, she was like
Dialogue: 0,0:16:03.02,0:16:08.93,Default,,0000,0000,0000,,abusive or stupid or whatever. Then maybe\Nyou ought not to obey her even though she
Dialogue: 0,0:16:08.93,0:16:14.24,Default,,0000,0000,0000,,is your mother. So we have to add a\Npremise, namely, you ought to obey your
Dialogue: 0,0:16:14.24,0:16:19.24,Default,,0000,0000,0000,,mother. Now we can say she's your mother,\Nyou ought to obey your mother therefore
Dialogue: 0,0:16:19.24,0:16:24.54,Default,,0000,0000,0000,,you ought to obey her, but of course that\Na supressed premise you ought to obey your
Dialogue: 0,0:16:24.54,0:16:29.22,Default,,0000,0000,0000,,mother is questionable because maybe she\Nwas abusive or stupid. So let's add
Dialogue: 0,0:16:29.22,0:16:34.27,Default,,0000,0000,0000,,another supressed premise that your mother\Nwas not abusive or stupid, of course we a
Dialogue: 0,0:16:34.27,0:16:39.07,Default,,0000,0000,0000,,lso have to qualify that moral premise\Nthat you ought to obey your mother if
Dialogue: 0,0:16:39.07,0:16:43.81,Default,,0000,0000,0000,,she's not abusive or stupid. And now the\Nargument looks like this - she's your
Dialogue: 0,0:16:43.81,0:16:48.90,Default,,0000,0000,0000,,mother, you ought to obey your mother if\Nshe's not abusive or stupid. Your mother
Dialogue: 0,0:16:48.90,0:16:54.88,Default,,0000,0000,0000,,was not abusive or stupid. Therefore, you\Nought to obey her. An notice that here, we
Dialogue: 0,0:16:54.88,0:17:00.41,Default,,0000,0000,0000,,added a moral premise about the fact that\Nyou ought to obey your mother under
Dialogue: 0,0:17:00.41,0:17:05.87,Default,,0000,0000,0000,,certain conditions. Namely, she's not\Nabusive or stupid. And the second premise
Dialogue: 0,0:17:05.87,0:17:11.04,Default,,0000,0000,0000,,is she was not abusive or stupid. So, we\Nhave a moral premise and a factual
Dialogue: 0,0:17:11.04,0:17:16.22,Default,,0000,0000,0000,,premise, both being suppressed in the\Nargument that you ought to obey her
Dialogue: 0,0:17:16.22,0:17:22.63,Default,,0000,0000,0000,,because she's your mother. Here's another\N. It's the Sabbath, so you ought to go to
Dialogue: 0,0:17:22.63,0:17:28.52,Default,,0000,0000,0000,,synagogue. Well, that's clearly not valid.\NOne suppressed premise is that you're
Dialogue: 0,0:17:28.52,0:17:34.29,Default,,0000,0000,0000,,Jewish. The other suppressed premise is\Nyou haven't been to synagogue already
Dialogue: 0,0:17:34.29,0:17:39.91,Default,,0000,0000,0000,,today, on this Sabbath. And the third\Nsuppressed premise is a religious norm,
Dialogue: 0,0:17:39.91,0:17:45.74,Default,,0000,0000,0000,,mainly Jews ought to go to the synagogue\Non the Sabbath. And you need that whole
Dialogue: 0,0:17:45.74,0:17:50.91,Default,,0000,0000,0000,,bunch of suppressed premises in order to\Nget from the premise, that it's the
Dialogue: 0,0:17:50.91,0:17:56.34,Default,,0000,0000,0000,,Sabbath, to the conclusion, that you ought\Nto go to synagogue. And of course all of
Dialogue: 0,0:17:56.34,0:18:01.50,Default,,0000,0000,0000,,those premises might be questionable. Some\Npeople would question them. Some people
Dialogue: 0,0:18:01.50,0:18:06.91,Default,,0000,0000,0000,,would deny them, but the point here is to\Nfigure out what's being assumed by someone
Dialogue: 0,0:18:06.91,0:18:11.81,Default,,0000,0000,0000,,who gave the original argument. And\Nanybody who says it's the Sabbath, so you
Dialogue: 0,0:18:11.81,0:18:16.20,Default,,0000,0000,0000,,ought to go to synagogue, seems to be\Nassuming you're Jewish, you haven't been
Dialogue: 0,0:18:16.20,0:18:21.15,Default,,0000,0000,0000,,already, and Jews ought to go to the\Nsynagogue on the Sabbath. So what these
Dialogue: 0,0:18:21.15,0:18:26.94,Default,,0000,0000,0000,,suppressed premises do is they bring out\Nthe assumptions that somebody who gave
Dialogue: 0,0:18:26.94,0:18:32.87,Default,,0000,0000,0000,,that argument must have had in mind. The\Nlast case is a little bit trickier. It has
Dialogue: 0,0:18:32.87,0:18:38.80,Default,,0000,0000,0000,,to do with linguistic suppressed premises.\NJen and Bob are first cousins, therefore
Dialogue: 0,0:18:38.80,0:18:47.47,Default,,0000,0000,0000,,they share a grandparent. Now, in order to\Nunderstand that argument, you have to know
Dialogue: 0,0:18:47.47,0:18:52.16,Default,,0000,0000,0000,,that first cousins always share a\Ngrandparent. That just follows from the
Dialogue: 0,0:18:52.16,0:18:58.85,Default,,0000,0000,0000,,definition of what a first cousin is. But\Ni t's not quite so obvious, is that
Dialogue: 0,0:18:58.85,0:19:04.00,Default,,0000,0000,0000,,biological sisters are female. And so,\Nthere's even more need to bring out that
Dialogue: 0,0:19:04.00,0:19:09.36,Default,,0000,0000,0000,,linguistics suppressed premise in this\Ncase. But it's still not necessary to make
Dialogue: 0,0:19:09.36,0:19:14.84,Default,,0000,0000,0000,,the argument valid. It's just not possible\Nthat Janet and Bob are first cousins, and
Dialogue: 0,0:19:14.84,0:19:19.60,Default,,0000,0000,0000,,they don't share a grandparent. Because\Nthe suppressed premise is purely
Dialogue: 0,0:19:19.60,0:19:24.66,Default,,0000,0000,0000,,linguistic, so it's necessarily true, so\Nyou can't possibly be first cousins
Dialogue: 0,0:19:24.66,0:19:29.70,Default,,0000,0000,0000,,without sharing a grandparent. Still, the\Npoint of bringing out linguistic
Dialogue: 0,0:19:29.70,0:19:34.94,Default,,0000,0000,0000,,suppressed premises is to show every\Nlittle step along the way. The argument
Dialogue: 0,0:19:34.94,0:19:39.95,Default,,0000,0000,0000,,might be valid without those suppressed\Nlinguistic premises, but we won't
Dialogue: 0,0:19:39.95,0:19:45.15,Default,,0000,0000,0000,,understand why it's valid and why the\Nreasoning goes through unless we add the
Dialogue: 0,0:19:45.15,0:19:51.41,Default,,0000,0000,0000,,linguistics suppressed premise. So it's\Nworth doing that. Shh. Here's a trick.
Dialogue: 0,0:19:51.41,0:20:00.40,Default,,0000,0000,0000,,Don't tell anybody. Okay? It's just\Nbetween me and you. You can always make
Dialogue: 0,0:20:00.40,0:20:06.92,Default,,0000,0000,0000,,any argument valid just by adding a\Nsuppressed premise that says if the
Dialogue: 0,0:20:06.92,0:20:14.07,Default,,0000,0000,0000,,premises are true, then the conclusion is\Ntrue. But don't tell anybody, because if
Dialogue: 0,0:20:14.07,0:20:19.99,Default,,0000,0000,0000,,people start doing that, and they start\Nmaking the argument valid that way, with
Dialogue: 0,0:20:19.99,0:20:26.27,Default,,0000,0000,0000,,that suppressed premise, we're never going\Nto understand the pathway of reasoning. It
Dialogue: 0,0:20:26.27,0:20:31.10,Default,,0000,0000,0000,,makes the argument valid, but it doesn't\Nserve the real purpose of adding
Dialogue: 0,0:20:31.58,0:20:37.23,Default,,0000,0000,0000,,suppressed premises which is to understand\Nthe pathway of reasoning. So you can do
Dialogue: 0,0:20:37.23,0:20:42.68,Default,,0000,0000,0000,,that. It's a trick. It makes that argument\Nvalid but it doesn't achieve our goal
Dialogue: 0,0:20:42.68,0:20:48.33,Default,,0000,0000,0000,,because our goal is not just to make the\Nargument valid, it's to make the argument
Dialogue: 0,0:20:48.33,0:20:54.60,Default,,0000,0000,0000,,valid so that we can understand the\Npathway of reasoning. So it's important to
Dialogue: 0,0:20:54.60,0:21:02.34,Default,,0000,0000,0000,,know that trick, but don't use it unless\Nyou have to. The examples so far have been
Dialogue: 0,0:21:02.34,0:21:07.85,Default,,0000,0000,0000,,pretty trivial, I admit it. But the same\Npoints apply in very important context
Dialogue: 0,0:21:07.85,0:21:13.57,Default,,0000,0000,0000,,such as politic debates, politician can\Nsuppress premises in perfectly legitimate
Dialogue: 0,0:21:13.57,0:21:19.51,Default,,0000,0000,0000,,ways. They're just trying to save time and\Nmake their arguments more efficient, maybe
Dialogue: 0,0:21:19.51,0:21:25.62,Default,,0000,0000,0000,,even sometimes clearer because you don't\Nhave to add all those little details. But
Dialogue: 0,0:21:25.62,0:21:31.68,Default,,0000,0000,0000,,sometimes politicia ns abuse suppressed\Npremises. They take things for granted
Dialogue: 0,0:21:31.68,0:21:37.91,Default,,0000,0000,0000,,that they shouldn't be taking for granted.\NHere's an example. A politician might
Dialogue: 0,0:21:37.91,0:21:43.98,Default,,0000,0000,0000,,argue, my opponent is soft on crime\Nbecause he's opposed to the death penalty.
Dialogue: 0,0:21:44.30,0:21:50.02,Default,,0000,0000,0000,,Well, that assumes, as a suppressed\Npremise, that anyone who's opposed to the
Dialogue: 0,0:21:50.02,0:21:56.14,Default,,0000,0000,0000,,death penalty must be soft on crime. And\Nif the politician were to come out and say
Dialogue: 0,0:21:56.14,0:22:01.46,Default,,0000,0000,0000,,that, it would seem pretty questionable,\Nand that's probably why he suppresses it.
Dialogue: 0,0:22:01.72,0:22:07.45,Default,,0000,0000,0000,,And then another politician might say, my\Nopponent is in favor of the death penalty,
Dialogue: 0,0:22:07.45,0:22:13.03,Default,,0000,0000,0000,,so he must not have read all the recent\Nstudies that show that the death penalty
Dialogue: 0,0:22:13.03,0:22:18.98,Default,,0000,0000,0000,,doesn't deter. Well that argument assumes\Nthe suppressed premise that if you've read
Dialogue: 0,0:22:18.98,0:22:23.56,Default,,0000,0000,0000,,those studies you'ld be convinced by them,\Nand that the only point of the death
Dialogue: 0,0:22:23.56,0:22:29.64,Default,,0000,0000,0000,,penalty is deterrence. But the point is\Nthat politicians talking about extremely
Dialogue: 0,0:22:29.64,0:22:34.05,Default,,0000,0000,0000,,important issues can take things for\Ngranted, that if they were brought into
Dialogue: 0,0:22:34.05,0:22:38.86,Default,,0000,0000,0000,,the light of day will be questionable, and\Nthat's why they hide them. So when you're
Dialogue: 0,0:22:38.86,0:22:43.50,Default,,0000,0000,0000,,listening to people give arguments on\Nimportant issues in your life, then you
Dialogue: 0,0:22:43.50,0:22:49.80,Default,,0000,0000,0000,,ought to be looking for these suppressed\Npremises and asking yourself whether or
Dialogue: 0,0:22:49.80,0:22:55.95,Default,,0000,0000,0000,,not you really ought to be agreeing with\Nthem about that assumption. Finally, we
Dialogue: 0,0:22:55.95,0:23:01.63,Default,,0000,0000,0000,,finished reconstruction. Yipee, right? Oh,\Nno, not quite, because there's one more
Dialogue: 0,0:23:01.63,0:23:06.95,Default,,0000,0000,0000,,stage, and that stage is drawing a\Nconclusion. Of course, if we've come up
Dialogue: 0,0:23:06.95,0:23:12.35,Default,,0000,0000,0000,,with a sound reconstruction, then we know\Nthat the argument is sound, and we know
Dialogue: 0,0:23:12.35,0:23:18.82,Default,,0000,0000,0000,,that the conclusion is true, because every\Nsound argument has a true conclusion. But
Dialogue: 0,0:23:18.82,0:23:23.52,Default,,0000,0000,0000,,if we don't come up with a sound\Nreconstruction, then what do we say? Well,
Dialogue: 0,0:23:23.52,0:23:28.42,Default,,0000,0000,0000,,you've got to ask, whose fault is it? It\Nmight be the fault of the argument. Maybe
Dialogue: 0,0:23:28.42,0:23:33.12,Default,,0000,0000,0000,,we couldn't come up with a sound\Nreconstruction because there just is no
Dialogue: 0,0:23:33.12,0:23:37.24,Default,,0000,0000,0000,,sound reconstruction. But maybe we\Ncouldn't come up with a sound
Dialogue: 0,0:23:37.24,0:23:42.20,Default,,0000,0000,0000,,reconstruction because we just weren't\Nimaginative enough, or try hard enough.
Dialogue: 0,0:23:42.20,0:23:47.59,Default,,0000,0000,0000,,Still, if we try really long an hard, and\Ncharitably interpret the a rgument as best
Dialogue: 0,0:23:47.59,0:23:52.92,Default,,0000,0000,0000,,we can to make it, look as good as we can,\Nand we still can't make it sound. Then,
Dialogue: 0,0:23:52.92,0:23:58.31,Default,,0000,0000,0000,,we've at least got reason to believe that\Nthe argument's not sound. Of course, that
Dialogue: 0,0:23:58.31,0:24:03.57,Default,,0000,0000,0000,,doesn't mean that the conclusion's not\Ntrue, because unsound arguments can still
Dialogue: 0,0:24:03.57,0:24:09.11,Default,,0000,0000,0000,,have true conclusions. But at least we\Nknow that this argument doesn't prove that
Dialogue: 0,0:24:09.11,0:24:14.09,Default,,0000,0000,0000,,the conclusion is true. And so, this\Nmethod of reconstruction can lead us
Dialogue: 0,0:24:14.09,0:24:19.29,Default,,0000,0000,0000,,either to the belief that the argument is\Nsound, because we found the sound
Dialogue: 0,0:24:19.29,0:24:24.83,Default,,0000,0000,0000,,reconstruction, or to the conclusion is\Nnot sound, because we tried long and hard
Dialogue: 0,0:24:24.83,0:24:30.23,Default,,0000,0000,0000,,to find a sound reconstruction that\Ndidn't, but that's still not going to show
Dialogue: 0,0:24:30.23,0:24:36.55,Default,,0000,0000,0000,,us that the conclusion of the argument is\Nfalse. The point of reconstruction then is
Dialogue: 0,0:24:36.55,0:24:42.35,Default,,0000,0000,0000,,to reach a conclusion on this issue of is\Nthe argument sound or not. And if we try
Dialogue: 0,0:24:42.35,0:24:48.01,Default,,0000,0000,0000,,our best and do it as well as we can and\Ncharitably, then we can be justified in
Dialogue: 0,0:24:48.01,0:24:51.12,Default,,0000,0000,0000,,believing that the argument is sound or\Nnot.