"All" introduces a sufficient condition, so we would diagram this sentence as follows:
C ==> V not V ==> not C
Premise: "X is a carrot."
P: C
Conclusion: "X is a vegetable."
C: V
This is a valid argument because we are invoking the sufficient condition, i.e. carrot, to conclude the necessary condition, i.e. vegetable.
Now let's compare with Example 2:
Principle: "Anyone name Sue is a girl."
"Anyone" also introduces a sufficient condition, so we would diagram this sentence as follows:
S ==> G not G ==> not S
Premise: "X is named Sue."
P: S
Conclusion: "X is a girl."
C: G
Logically, the structure of this argument is identical to Example 1, i.e. invoking sufficient to conclude necessary.
This issue with Example 2 is the Johnny Cash song we start playing while discussing this example, i.e. "A Boy Named Sue."
So the issue with Example 2 is that the principle, i.e. anyone named Sue is a girl, is not true.
These concepts are discussed in more detail when you get to our Weaken lesson, but for now just remember, there are two ways to weaken an argument:
(1) show that a premise is false (Example 2)
OR
(2) show that the conclusion does not follow from the premises even if those premises are true (Example 3)
Hope that helps! Please let us know if you have any other questions.
kluedtke5on October 5, 2017
Hey! I'm still stuck on the Johnny Cash song being a true premise. It's just a song... how can we assume a song to be true? There are lots of songs about fictitious things and I believe the majority of people named Sue are girls, leading me to assume it's true.
Mehranon October 7, 2017
The point of this example is to show how to attack an argument by taking issue with a premise.
While you are probably correct that the majority of people named Sue are girls, the premise we are taking issue with is that "anyone named Sue is a girl."
All that would be required to disprove this absolute statement is one counterexample, i.e. a single man in the history of the world named Sue.
Hope that helps! Please let us know if you have any other questions.
P.S. While the song "A Boy Named Sue" was made hugely popular by Johnny Cash in 1969, the song was actually written by none other than Shel Silverstein. Silverstein's inspiration for the song's title came from a man named Sue K. Hicks, who was a judge in the state of Tennessee.
kluedtke5on November 18, 2017
Thank you for the clear response. This was really helpful and I love the PS!! Thank you so much and I'm loving this course!
Alec-Juliánon June 19, 2018
Are we expected to know musical trivia for the LSAT? I don't understand how a song by Johnny Cash from the 60's makes this premise untrue. The song was not meant to be taken seriously, it is fictional
Christopheron June 21, 2018
No, you won't need to know musical trivia. It's a joke. As to how it would make a premise untrue, that type of thing can come up. The issue there is that if there is an exception to a rule that the argument relies upon, then you can weaken the argument. In fact, you're essentially doing the same thing by pointing out that the song is fictional. The thing to keep in mind on the LSAT is that only the information that is written on the page matters. It requires no outside knowledge.
Alec-Juliánon June 25, 2018
"The thing to keep in mind on the LSAT is that only the information that is written on the page matters. It requires no outside knowledge."
Thank you for proving my point for me. So why introduce the song at all then?
arid14on June 27, 2018
I've completed all the flashcards and the video yet it still says I'm only 89% complete-- what am I missing because nothing is showing up incomplete?
Christopheron June 28, 2018
Introducing the song does two things. It makes a joke (forgive us the levity), and it illustrates how to attack an argument. On any question on the LSAT, you'll only need to take the information on the page into account. However, if a question gives you a series of premises and then evidence suggesting that one of those premises could be false (if there is there's even the possibility of there being a man named Sue, then the premise COULD be false), then it weakens the argument. It's important to be able to recognize how premises and their truth or falsehood affect arguments.
Does that make sense?
lillieroney7on July 10, 2018
Can you please send me the PDF so I can take notes? I don't have it in my email inbox. Thanks!
erospenceron July 11, 2018
Could you email me a copy of the lesson notes? Thank you.
VictoriaCarloneon July 17, 2018
Could you please email me a copy of the lesson notes as well? Thank you.
Mehranon July 19, 2018
@VictoriaCarlone please direct any support related issues to our support staff by tapping "support" from the left menu or by calling 855.483.7862 ext. 2 Monday-Friday 9am-6pm PT.
Please use these message boards for content-related questions only. Thank you.
Mehranon July 19, 2018
@VictoriaCarlone also make sure you are checking your spam folder.
Edenon October 23, 2018
on p.12 of the PDF, question #4, you wrote that "all of the following statements must be false EXCEPT": correct: CBT and incorrect: MBF. Why wouldn't you write correct: MBT (which includes CBT)?
theonlybykon November 28, 2018
Hi. Did u send out the Success kit and book The Road to 180? I have yet to receive either.
Jacob-Ron December 1, 2018
@theonlybyk I’ve forwarded your question, but in the future please use these message boards only for content-related questions.
Please direct any support related issues to our support staff by tapping “support†from the left menu or by calling 855.483.7862 ext. 2 Monday - Friday 9am-6pm PST.
Thank you!
corysteinleon December 18, 2018
Hi! Quick question - I'm not at weakening arguments yet, so this may make sense later. For the 'Sue' example - should we assume all premises provided on the LSAT are true unless presented other evidence directly questioning/attacking the premises? I don't want to get into the trap of 'overthinking' and trying to question premises I don't need to (wastes time). Thank you!
Ravion December 18, 2018
Great question! Yes, that is correct. Assume all premises provided on the LSAT are true unless presented evidence that suggests otherwise. Mehran's 'Sue' example was used to illustrate one way in which you can attack an argument (directly attack the premises). However, as he notes in the video, for our purposes on the LSAT, we're focusing on seeing whether or not the conclusion follows logically from the stated premises.
In day-to-day life, many arguments you'll here will be two or more parties disputing each other's premises. However, on the LSAT, the test writers are looking to see if you can examine an argument and show how even when the premises are accepted as true, the conclusion doesn't necessarily follow.
Hope that helps. Let us know if you have more questions!
lillieroney7on January 2, 2019
I am needing help with the Missing Premise and Argument Completion Drills under the Sufficient and Necessary Conditions lesson. I do not understand how to solve them at all. Any assistance is greatly appreciated. Thank you.
Ravion January 2, 2019
Hey, I would first recommend rewatching the video lesson to internalize the information Mehran is providing on how to solve these questions. Often, watching the instructional videos once isn't enough to retain all of the information in them.
After watching the videos again that cover sufficient and necessary conditions, try going over more of the explanations that Mehran goes through in the videos as he does them. This will give you a more natural feel for the questions.
Solving these types of questions can be challenging, but the key is always making sure that you have a clear understanding of everything that's in the stimulus.
If you could, please provide some specific examples of problems you're having so that we can walk you through the solutions. This will also help us to know exactly where in these problems you're having the most difficulty. When you have a chance, send over some of the ones that you're currently not able to solve, and we'll go over it with you.
In the meantime, if you have any additional questions, let us know!
Marianaon January 10, 2019
Is there another way of thinking about logical equivalents of questions (yin and yang)? I'm finding the yin/yang process shown to be confusing me even further. (I get that it isn't about yin and yang, but rather the process of reframing the question to make finding the correct answer easier.)
Thanks!
Marianaon January 10, 2019
Also, I am going through logical reasoning question types, and bizarro argument exchange and bizarro illustration have both come up. Neither of these were introduced in the video. Can someone explain the concept of bizarro to me?
connormackbrockon May 10, 2019
I never received an email with a .pdf of the lesson notes. Is there anywhere I may be able to access them?
Ravion May 10, 2019
@Mariana,
Great question. Could you provide me with an example of what you're describing? It'll be easier for us to take a look if you can provide a specific problem where this is coming up for you.
Regarding "Bizarro," bizarro just means “EXCEPTâ€.
So for example, “Each of the following must be true EXCEPTâ€.
That is a must be true bizarro question.
The four incorrect answer choices must be true while the correct answer choice is not necessarily true.
Hope that helps! Please let us know if you have any other questions.
@Noname,
Please direct any support related issues to our support staff by tapping "support" from the left menu or by calling 855.483.7862 ext. 2 Monday-Friday 9am-6pm PT.
Our support channels are a much faster way to resolve these type of issues.
Please use these message boards for content-related questions only.
Thanks, and let us know if you have any questions!
Amber-Loweryon May 20, 2019
How can I tell the conclusion follows logically from the conclusion?
Ravion May 20, 2019
@Amber-Lowery,
Great question.
The question type you're referring to is a strengthen with a sufficient premise. These question types typically say things like
Which one of the following, if assumed, enables the psychologist's conclusion to be properly drawn?
The ethicist's conclusion follows logically if which one of the following is assumed?
The argument's conclusion follows logically if which one of the following is assumed?
Which one of the following, if assumed, enables the essayist's conclusion to be properly drawn?
The conclusion of the criminologist's argument is properly inferred if which one of the following is assumed?
The key giveaway in these question stems that tell us they're strengthen with a sufficient premise questions is that they all contain language that tells us that we're looking for an assumption that, if true, ENABLES THE CONCLUSION TO BE DRAWN/JUSTIFIES THE ARGUMENT, etc. In other words, we're looking for an assumption that, if true, makes the argument valid.
Sufficient premises are premises that, if we add them to the argument, automatically make the argument valid.
Does this help? Let us know if you have any more questions!
abaldeck2018on May 27, 2019
Hi,
Where do I find the PDFs for the lesson videos?
Thanks!
Ravion May 27, 2019
Hey there,
Feel free to direct any support related issues to our support staff by tapping "support" from the left menu or by calling 855.483.7862 ext. 2 Monday-Friday 9am-6pm PT.
Please save the boards for content-related questions. Thanks!
sigmajonez14on May 28, 2019
@ mehran How do I know what we the main variables when I extract the logic from the paragraph
Ravion May 28, 2019
@sigmajonez14, the wording of the paragraph will guide you to know which variables/terms go in the sufficient condition of your diagram, and which go in the necessary condition. Reviewing the video lessons on sufficient and necessary conditions (and quantifiers) will help immensely.
Hope this helps. Let us know if you have any more questions!
romeodelta4366on May 30, 2019
I was under the impression that we are supposed to assume the premises are true, regardless of our outside knowledge. How are we to decipher whether or not the LSAT is testing our ability to make a logical conclusion about a set of premises if we're questioning the premises. I thought the name of the game is to find the flaw in the conclusion or a gap in the premises, not a specific premise itself. As a matter of fact, every other resource that I have used has specifically said that if the LSAT says an orange is green, then it is green for the sake of that question.
Ravion May 31, 2019
@romeodelta4366, you're 100% correct in that you're supposed to assume the premises are true, regardless of our outside knowledge. The purpose of the video lesson that attacks a premise (with the "Sue" reference) is merely to show one manner in which arguments can be attacked. As you probably know from your day-to-day life, people often attack the arguments of others by attacking their premises. This is the easiest and cheapest form of argumentation. However, it's not what the LSAT tests. We assume the premises are true and look for the flaw in either the conclusion or a gap between the premises and conclusion. Keep on approaching the test like this, and keep assuming the premises are true.
on September 23, 2020
Just for clarification on the valid arguments section, if we were not taking the Johnny Cash song into consideration, the argument would be valid right. Because we are supposed to accept all premises as true as we arrive to the conclusion right? You including the song was you taking it a step further to weaken the argument??
ZackSaltmanon December 4, 2020
Hi, I did not understand how the main point and argument structure ques are also must be true questions. Additionally, what is the diff between strengthen questions that are necessary premise and sufficient premise. Also, I wasn't clear what an argument evaluation is?
Karlitaon May 25, 2021
Hi, I'm having trouble understanding questions 3 & 4, the ones that use the word "EXCEPT", on the True Vs. false section.
I had the answers switched for both of these.
i.e. question 3. my correct answer was - not nec. true. My incorrect answer was must be true.
