1 00:00:00,360 --> 00:00:02,600 Here is an argument about a chemist. 2 00:00:03,280 --> 00:00:06,560 Four of the five answer choices are also about chemists. 3 00:00:07,320 --> 00:00:11,420 The credited answer is about a chess tournament, and those four chemistry answers 4 00:00:11,720 --> 00:00:12,280 are the trap. 5 00:00:13,244 --> 00:00:13,692 Hold on. 6 00:00:14,212 --> 00:00:18,713 The answer that's on the same topic as the question is the wrong one? 7 00:00:19,986 --> 00:00:23,506 On the family we're doing today, almost always. 8 00:00:24,206 --> 00:00:29,266 By the end you'll know why same topic is a warning light, not a comfort. 9 00:00:30,306 --> 00:00:32,806 But first, reach back one episode. 10 00:00:33,753 --> 00:00:35,672 Quick retrieval from Episode 1. 11 00:00:36,342 --> 00:00:39,342 What were the three parts of every argument skeleton? 12 00:00:40,062 --> 00:00:42,362 Take a beat, try to name them before I do. 13 00:00:43,326 --> 00:00:46,595 Conclusion, premises, and the assumption. 14 00:00:47,216 --> 00:00:49,106 The bridge across the gap. 15 00:00:50,496 --> 00:00:55,406 That skeleton is the whole engine today, because both of today's question families 16 00:00:55,426 --> 00:00:57,566 are pure shape questions. 17 00:00:57,646 --> 00:01:00,246 They don't care whether the argument is true. 18 00:01:00,306 --> 00:01:04,986 They care about its structure, which is exactly the skeleton lens from Episode 1. 19 00:01:05,806 --> 00:01:07,116 So here's the one objective. 20 00:01:07,646 --> 00:01:13,086 By the end, you'll strip the topic off any argument and name its logical shape in 21 00:01:13,206 --> 00:01:17,626 one sentence, fast enough to match two arguments about totally different subjects. 22 00:01:18,506 --> 00:01:19,106 Three moves. 23 00:01:19,766 --> 00:01:22,886 Move one, principle questions, both directions. 24 00:01:23,566 --> 00:01:26,866 Move two, parallel reasoning, matching the shape. 25 00:01:27,566 --> 00:01:31,946 Move three, parallel flaw, matching the shape and the mistake. 26 00:01:32,807 --> 00:01:36,147 And the handle for all three is what, abstract to the shape? 27 00:01:37,105 --> 00:01:38,734 Abstract to the shape. 28 00:01:39,374 --> 00:01:41,814 Strip the topic, keep the structure. 29 00:01:42,514 --> 00:01:46,574 Lock that phrase down now, because we lean on it the entire episode. 30 00:01:47,594 --> 00:01:50,334 Picture a house rule on a fridge magnet. 31 00:01:50,934 --> 00:01:55,674 A principle is just that, a general, transferable rule. 32 00:01:55,704 --> 00:01:58,534 A case is one specific instance of it. 33 00:01:59,274 --> 00:02:00,714 Here's the move people miss. 34 00:02:01,514 --> 00:02:06,654 Principle questions run in two directions, and the stem tells you which one you're 35 00:02:06,754 --> 00:02:06,904 in. 36 00:02:07,751 --> 00:02:11,310 Two directions meaning which side I'm handed and which side I'm hunting for? 37 00:02:12,496 --> 00:02:13,376 That's the split. 38 00:02:14,096 --> 00:02:16,856 Direction A, identify the principle. 39 00:02:17,696 --> 00:02:22,236 The stimulus hands you a specific judgment, and the answers are broad rules. 40 00:02:22,836 --> 00:02:27,085 You ask, what general rule is this one judgment an instance of? 41 00:02:28,196 --> 00:02:31,376 Direction B, apply the principle. 42 00:02:31,436 --> 00:02:36,336 The stimulus hands you the broad rule, and the answers are specific cases. 43 00:02:36,365 --> 00:02:40,756 You ask, which situation does this rule actually cover? 44 00:02:41,151 --> 00:02:46,021 So a principle is a rule, a case is one example of the rule, 45 00:02:46,601 --> 00:02:50,081 and the stem just tells me which one I'm holding and which one to go find. 46 00:02:50,761 --> 00:02:51,501 That's the whole frame? 47 00:02:52,868 --> 00:02:53,418 That's the frame. 48 00:02:54,018 --> 00:02:58,917 Now the part naive courses get wrong, and this is the key point. 49 00:02:58,948 --> 00:03:02,378 The word principle is not its own question type. 50 00:03:02,938 --> 00:03:06,298 It rides on top of types you already know. 51 00:03:06,338 --> 00:03:11,918 When you read a principle out of a case, that's just Must Be True or Most Strongly 52 00:03:11,938 --> 00:03:12,408 Supported. 53 00:03:13,218 --> 00:03:18,518 When the principle is used to justify a conclusion, that's Strengthen or Sufficient 54 00:03:18,558 --> 00:03:19,078 Assumption. 55 00:03:19,858 --> 00:03:23,258 When a principle is misapplied, that's a Flaw question. 56 00:03:24,098 --> 00:03:29,138 The word principle only tells you a general rule connects to a specific case. 57 00:03:29,718 --> 00:03:31,238 It doesn't tell you the task. 58 00:03:32,248 --> 00:03:37,508 So if I invent a special principle technique, I'm building a tool for a question 59 00:03:37,538 --> 00:03:38,638 that doesn't exist. 60 00:03:39,491 --> 00:03:42,021 A tool for a phantom. 61 00:03:42,081 --> 00:03:44,001 So here's the discipline. 62 00:03:44,121 --> 00:03:48,981 Read the rest of the stem to learn the real task, then solve it with that type's 63 00:03:49,061 --> 00:03:49,361 method. 64 00:03:50,261 --> 00:03:52,721 Principle is a flavor, not a recipe. 65 00:03:53,680 --> 00:03:56,209 Let's apply a principle, fully worked. 66 00:03:56,869 --> 00:03:57,289 The rule. 67 00:03:57,989 --> 00:04:02,089 You may skip chores only if you've finished all your homework. 68 00:04:02,749 --> 00:04:05,269 Hear those two words, only if. 69 00:04:05,899 --> 00:04:08,899 They mark finishing homework as the necessary condition. 70 00:04:09,549 --> 00:04:12,009 So translate it into plain if-then. 71 00:04:12,929 --> 00:04:16,469 If you skipped chores, then you must have finished your homework. 72 00:04:17,079 --> 00:04:19,139 That's the only direction the rule runs. 73 00:04:20,192 --> 00:04:20,732 Wait. 74 00:04:20,872 --> 00:04:25,672 I want to read it as, if you finished your homework, then you're allowed to skip 75 00:04:25,732 --> 00:04:26,132 chores. 76 00:04:26,872 --> 00:04:28,172 Isn't that the same rule? 77 00:04:29,378 --> 00:04:30,367 Defend it. 78 00:04:30,507 --> 00:04:31,687 Walk me through why. 79 00:04:32,912 --> 00:04:35,632 The rule links homework and skipping chores. 80 00:04:36,062 --> 00:04:39,082 So finishing homework should buy you the right to skip. 81 00:04:39,702 --> 00:04:42,042 Finished homework, therefore skip allowed. 82 00:04:42,522 --> 00:04:43,552 That feels airtight to me. 83 00:04:44,668 --> 00:04:50,968 It feels airtight, and it's wrong, and this is the single most tested error on the 84 00:04:50,988 --> 00:04:51,378 section. 85 00:04:52,388 --> 00:04:57,328 Only if marks a necessary condition, not a sufficient one. 86 00:04:57,388 --> 00:05:01,128 Finishing homework is required in order to skip chores. 87 00:05:01,188 --> 00:05:03,888 It does not, by itself, grant permission. 88 00:05:04,588 --> 00:05:09,228 A parent can say, yes you finished everything, now do the dishes anyway, 89 00:05:09,748 --> 00:05:11,428 and the rule is not broken. 90 00:05:12,348 --> 00:05:15,878 You treated a necessary condition as if it were sufficient. 91 00:05:16,840 --> 00:05:19,380 So the rule only fires one way. 92 00:05:19,820 --> 00:05:25,140 It tells me what must have been true if someone skipped, not what someone gets to do 93 00:05:25,150 --> 00:05:26,170 once homework's done. 94 00:05:27,338 --> 00:05:31,458 Now you own it, and it sticks harder because you were certain a second ago. 95 00:05:32,258 --> 00:05:34,898 So test two cases against the rule. 96 00:05:34,978 --> 00:05:38,598 Case one, a kid finished homework but did chores anyway. 97 00:05:39,358 --> 00:05:40,278 Does the rule judge her? 98 00:05:41,178 --> 00:05:41,718 No. 99 00:05:41,758 --> 00:05:46,098 The rule only restricts skipping, and doing chores is never a violation. 100 00:05:47,018 --> 00:05:50,678 Case two, a kid skipped chores without finishing homework. 101 00:05:51,318 --> 00:05:53,158 There's your one true violation. 102 00:05:53,598 --> 00:05:56,258 That's the only situation the rule actually governs. 103 00:05:57,358 --> 00:06:01,638 On the test, the trap answer will share the topic, chores and homework, 104 00:06:01,658 --> 00:06:03,898 but never actually trip the trigger. 105 00:06:03,978 --> 00:06:07,898 Or it'll flip sufficiency and necessity, exactly the way you just did. 106 00:06:08,976 --> 00:06:10,485 Now parallel reasoning. 107 00:06:11,025 --> 00:06:11,625 The task. 108 00:06:12,165 --> 00:06:16,405 Find the answer whose argument has the same logical shape as the stimulus, 109 00:06:16,745 --> 00:06:17,705 no matter the subject. 110 00:06:18,485 --> 00:06:19,345 So what is a shape? 111 00:06:20,045 --> 00:06:21,445 Picture four molds. 112 00:06:22,065 --> 00:06:25,685 A conditional chain, A leads to B leads to C. 113 00:06:26,445 --> 00:06:28,945 A causal claim, X caused Y. 114 00:06:29,725 --> 00:06:34,575 An analogy, these two things are alike, so what's true of one is true of the other. 115 00:06:35,385 --> 00:06:39,525 And a generalization, these samples, therefore the whole. 116 00:06:40,245 --> 00:06:41,565 The topic is irrelevant. 117 00:06:42,145 --> 00:06:43,305 Only the mold counts. 118 00:06:44,211 --> 00:06:47,511 Give me two on different topics so I can hear them rhyme. 119 00:06:48,538 --> 00:06:49,538 Here's the stimulus. 120 00:06:50,318 --> 00:06:54,158 If the cafe is out of oat milk, I get tea. 121 00:06:54,238 --> 00:06:56,618 If I get tea, I skip the pastry. 122 00:06:57,588 --> 00:07:00,898 The cafe is out of oat milk, so I'll skip the pastry. 123 00:07:02,158 --> 00:07:02,748 Abstract it. 124 00:07:03,658 --> 00:07:09,558 A leads to B, B leads to C, A is true, therefore C. 125 00:07:10,658 --> 00:07:12,978 A clean, valid conditional chain. 126 00:07:13,955 --> 00:07:18,875 And a correct parallel can be about anything, as long as it's that same chain? 127 00:07:19,908 --> 00:07:20,968 Anything. 128 00:07:21,028 --> 00:07:21,328 Watch. 129 00:07:22,108 --> 00:07:26,358 If the thermostat reads above seventy, the fan switches on. 130 00:07:26,388 --> 00:07:29,288 If the fan switches on, the vent opens. 131 00:07:29,328 --> 00:07:32,638 The thermostat reads above seventy, so the vent opens. 132 00:07:33,488 --> 00:07:37,147 Different world entirely, oat milk versus a vent. 133 00:07:37,208 --> 00:07:38,808 Your turn, say why it matches. 134 00:07:39,923 --> 00:07:41,703 Because it's the same chain. 135 00:07:42,203 --> 00:07:46,883 A leads to B, B leads to C, we're told A, so we land on C. 136 00:07:47,603 --> 00:07:49,363 Identical skeleton. 137 00:07:49,423 --> 00:07:51,203 The topic is just paint. 138 00:07:52,131 --> 00:07:53,980 The topic is just paint. 139 00:07:54,680 --> 00:07:58,340 Now here's the checklist, and the order matters because it buys you time. 140 00:07:59,120 --> 00:08:03,880 Move one, match the conclusion first, its strength and its quantifier. 141 00:08:04,540 --> 00:08:07,820 Must versus probably versus should versus most. 142 00:08:08,490 --> 00:08:11,120 That's your fastest filter, so be ruthless with it. 143 00:08:12,060 --> 00:08:16,040 Move two, match the premises, how many and how they combine. 144 00:08:16,940 --> 00:08:18,820 Move three, match validity. 145 00:08:19,310 --> 00:08:24,340 A valid stimulus needs a valid answer, and an invalid one needs an equally invalid 146 00:08:24,420 --> 00:08:24,670 answer. 147 00:08:25,920 --> 00:08:27,530 Run the conclusion filter on me. 148 00:08:27,930 --> 00:08:32,030 Say the oat milk argument ended in, so I'll probably skip the pastry, 149 00:08:32,400 --> 00:08:35,390 and an answer ends in, so the vent must open. 150 00:08:35,919 --> 00:08:36,080 Dead? 151 00:08:37,371 --> 00:08:38,200 Dead on sight. 152 00:08:39,020 --> 00:08:40,900 Probably is not must. 153 00:08:41,780 --> 00:08:45,360 You eliminate that answer without reading a single one of its premises. 154 00:08:46,300 --> 00:08:49,260 That's the whole payoff of matching conclusions first. 155 00:08:49,960 --> 00:08:54,340 You kill answers in seconds instead of diagramming all five. 156 00:08:54,414 --> 00:08:58,294 Parallel flaw is parallel reasoning plus a named error. 157 00:08:58,994 --> 00:09:00,874 One difference, and it's everything. 158 00:09:01,544 --> 00:09:03,993 The stimulus is always broken. 159 00:09:04,034 --> 00:09:08,534 The right answer has to reproduce both the same structure and the same specific 160 00:09:08,594 --> 00:09:09,014 mistake. 161 00:09:09,694 --> 00:09:12,154 So step one is the Episode 1 instinct. 162 00:09:12,654 --> 00:09:14,694 Where's the gap, and what kind of gap? 163 00:09:15,214 --> 00:09:16,394 Name it in the abstract. 164 00:09:17,334 --> 00:09:21,794 Step two, find the answer that makes that exact error on a different topic. 165 00:09:22,753 --> 00:09:26,153 Before you solve it, make me do the interleaving move. 166 00:09:26,753 --> 00:09:29,903 Which question type is this even, so I pick the right method? 167 00:09:30,900 --> 00:09:34,840 That discrimination is the real skill, so do it. 168 00:09:34,880 --> 00:09:36,540 Here's the stimulus. 169 00:09:36,600 --> 00:09:41,640 Everyone I know who drinks green smoothies is energetic, so green smoothies must 170 00:09:41,760 --> 00:09:42,500 cause energy. 171 00:09:43,340 --> 00:09:45,520 First, name the type and the flaw. 172 00:09:46,493 --> 00:09:51,682 It's a parallel flaw, and the flaw is the correlation-to-causation jump we hit a 173 00:09:51,722 --> 00:09:52,702 couple episodes back. 174 00:09:53,222 --> 00:09:57,472 They saw two things show up together and decided one causes the other. 175 00:09:58,092 --> 00:10:01,842 Maybe energetic people just happen to like green smoothies. 176 00:10:02,772 --> 00:10:07,392 Stated abstractly, concludes a causal claim from mere correlation. 177 00:10:08,272 --> 00:10:11,172 Now two answers, and pause to pick before I tell you. 178 00:10:12,032 --> 00:10:13,972 Answer one, same health topic. 179 00:10:14,812 --> 00:10:19,052 People who eat more fiber report better digestion, and the study controlled for 180 00:10:19,092 --> 00:10:23,112 other factors, so fiber likely improves digestion. 181 00:10:23,232 --> 00:10:25,182 Answer two, totally unrelated. 182 00:10:26,192 --> 00:10:30,502 Everyone I know who owns running shoes has run a marathon, so running shoes must 183 00:10:30,512 --> 00:10:31,892 cause people to run marathons. 184 00:10:32,882 --> 00:10:34,712 Pick one, then I'll talk. 185 00:10:35,106 --> 00:10:36,686 I'll take answer one. 186 00:10:36,746 --> 00:10:42,006 It's food and health, same lane as smoothies, and it's making a causal claim too. 187 00:10:42,466 --> 00:10:43,206 Feels like the match. 188 00:10:44,160 --> 00:10:46,280 And that's the trap closing on you. 189 00:10:46,910 --> 00:10:50,000 Answer one shares the topic, but look at the shape. 190 00:10:50,520 --> 00:10:54,150 It controlled for other factors, and it only says likely. 191 00:10:54,820 --> 00:10:57,290 That's a careful, basically valid argument. 192 00:10:58,060 --> 00:11:02,720 On a parallel flaw question, a valid answer is automatically wrong, 193 00:11:02,740 --> 00:11:05,340 because it doesn't reproduce the mistake. 194 00:11:05,440 --> 00:11:10,020 You quietly fixed the stimulus in your head and went hunting for a clean argument to 195 00:11:10,060 --> 00:11:11,280 match it. 196 00:11:11,486 --> 00:11:16,775 So it's answer two, the running shoes, even though it sounds nothing like smoothies. 197 00:11:17,741 --> 00:11:18,401 Answer two. 198 00:11:19,041 --> 00:11:24,381 It saw a correlation, owning shoes and running marathons, and leapt straight to 199 00:11:24,441 --> 00:11:25,071 causation. 200 00:11:25,821 --> 00:11:27,621 Same broken shape, new paint. 201 00:11:28,351 --> 00:11:31,871 The topic flipped completely, and that flip is the tell. 202 00:11:32,681 --> 00:11:34,561 Same topic is the decoy. 203 00:11:34,571 --> 00:11:38,121 The unrelated topic is usually where the credited answer hides. 204 00:11:39,141 --> 00:11:42,181 So back to your chemist and the chess tournament from the top. 205 00:11:42,801 --> 00:11:47,541 The four chemistry answers were paint, and the chess answer had the matching shape. 206 00:11:48,814 --> 00:11:50,803 That's the entire con. 207 00:11:50,863 --> 00:11:56,363 The test writer dresses a wrong shape in the right topic and bets you grab it on 208 00:11:56,403 --> 00:11:57,943 familiarity. 209 00:11:58,003 --> 00:12:02,003 So here's the heuristic, and I want it to be the last thing you carry out. 210 00:12:03,023 --> 00:12:04,463 Abstract to the shape. 211 00:12:05,363 --> 00:12:07,923 Strip the topic, keep the structure. 212 00:12:08,783 --> 00:12:09,343 One more time. 213 00:12:10,163 --> 00:12:12,803 Strip the topic, keep the structure. 214 00:12:13,883 --> 00:12:17,603 When two arguments wear different clothes but make the same moves, 215 00:12:18,043 --> 00:12:19,903 they are the same argument. 216 00:12:20,853 --> 00:12:25,902 And for principle, I read the rest of the stem so I solve it as the type it actually 217 00:12:25,983 --> 00:12:26,203 is. 218 00:12:27,066 --> 00:12:30,126 Because principle is a flavor, not a recipe. 219 00:12:31,606 --> 00:12:33,386 One piece of triage before we go. 220 00:12:34,146 --> 00:12:39,026 These questions are accurate but slow, since you have to read five full arguments. 221 00:12:39,686 --> 00:12:43,346 So abstract into plain words instead of diagramming everything, 222 00:12:43,946 --> 00:12:47,386 run the conclusion-match pass first, and when time's tight, 223 00:12:47,866 --> 00:12:48,926 flag and return. 224 00:12:49,536 --> 00:12:51,656 They're prime skip-and-come-back candidates. 225 00:12:52,906 --> 00:12:57,586 Between now and next time, open the practice bank, do five parallel questions, 226 00:12:58,046 --> 00:13:02,866 and force yourself to write the shape of each stimulus in one sentence before you 227 00:13:02,906 --> 00:13:04,086 even look at the answers. 228 00:13:05,253 --> 00:13:09,993 Next episode, we stop matching arguments and start describing them. 229 00:13:10,613 --> 00:13:12,673 The describe-the-argument family. 230 00:13:13,533 --> 00:13:17,413 Method of reasoning, role of a claim, and point at issue. 231 00:13:18,193 --> 00:13:23,553 Three questions that ask not whether the argument works, but what job each sentence 232 00:13:23,613 --> 00:13:24,793 is doing inside it. 233 00:13:25,553 --> 00:13:26,433 Bring the skeleton. 234 00:13:26,793 --> 00:13:28,492 We're going to label every bone.