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Sufficient assumptions | Video lesson

Watch one way to approach a question that asks you to identify a sufficient assumption on the logical reasoning section of the LSAT.

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  • blobby green style avatar for user abilyninodyssey
    How can you distinguish between a Necessary Assumption and a Sufficient Assumption? What key words should we look for?
    (5 votes)
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  • blobby green style avatar for user Niamh Moran
    How is the answer in this question different from a necessary assumption?
    (4 votes)
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  • blobby green style avatar for user ajfbb02
    I misunderstood the word "inappreciable." I thought it would mean too "large to appreciate" in this context, similar to how people say inconceivable. For that reason I answered C initially (I was incorrect of course, but I don't know how to improve my score with this information).
    (2 votes)
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  • blobby green style avatar for user zamantha7799
    would theses types of question strengthen ?
    (1 vote)
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    • blobby green style avatar for user cassiekh11
      Technically yes. Sufficient assumption questions are a type of strength. The difference is that SAQ makes the relationship between the support and conclusion a guarantee with no room to poke holes in the relationship vs a 'strengthen question' makes the relationship more robust but it doesn't necessarily always have to guarantee the conclusion. In order from least to most strengthening questions on the last, you have to strengthen questions, pseudo sufficient assumptions then sufficient assumptions. Hope this helps!
      (2 votes)
  • blobby green style avatar for user Kathleen Anne
    it is not clear to me why this couldn't also be an example of a necessary assumption.
    (1 vote)
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Video transcript

- [Instructor] To determine what kind of question this is, let's jump below the passage to the question itself. The conclusion of Morris's argument follows logically if which one of the following is assumed? This idea of an assumption guaranteeing a conclusion to follow from its evidence means that we are dealing with a sufficient assumption question. The answer will be a claim that ensures a connection from evidence to conclusion and the other four choices, the wrong choices, will be claims that don't allow the conclusion to follow from its support, either because they're not relevant or maybe they're a necessary assumption, but not a sufficient one, some reason like that. Pause your video now if you'd like to try this question on your own, otherwise, let's move on the the explanation. Okay, let's read the stimulus together. When reading for a sufficient assumption, concentrate on the main conclusion and main evidence of each speaker's argument. A lot of the times, you'll be able to detect a gap between the conclusion and evidence, and then the answer will close that gap. Okay, Morris says, "Computers, despite some people's expectations, "will have an inappreciable impact on education. "To be sure, computers are useful "for drills promoting memorization, though only a small part "of education can be accomplished through drills. "But machines cannot help students with any "of the higher intellectual functions we call understanding; "for that, human teachers are indispensable." Okay, first, let's mark our conclusion. We don't have any clear conclusion signal words that jump out at us right away, so let's decide what the entire argument is meant to try to prove. Morris opens up by predicting that computers, despite some people's expectations, will have an inappreciable impact on education. So, we ask ourselves, does the rest of the passage serve to support that idea? And the answer's yes. A good clue is also that Morris is rebutting what some people expect to happen. That's a very common conclusion structure. And then the rest of the passage explains Morris's thinking as to why computers won't really have a big impact on education. It's because even though computers are useful for drills promoting memorization, machines can't help students with any of the higher intellectual functions we call understanding, and there's our argument. In a nutshell, Morris is saying, computers can do some good things, but they won't have a big impact on education because they can't help students with higher intellectual functions. This last part of the passage here is sort of a parenthetical about teachers. It doesn't add anything material to the argument, so we can consider it background or context. Now, to find a gap in an argument, it can be extremely helpful to look for an idea or concept that kind of comes out of nowhere. So, look at our progression here. On the conclusion side, we're talking about how computers can't have a big impact on education. What's the star player of the evidence, though? The spotlight of the evidence is how computers can't help students with higher intellectual functioning, so we need to bridge these two concepts. In other words, what is Morris assuming? Well, Morris is assuming that if something can't help students with higher intellectual functioning, then that something can't have a big impact on education. If we assumed this to be true, then Morris's argument would be ironclad. The evidence would flow directly to the conclusion via this assumption and that is exactly what a sufficient assumption does. So, we have a super strong prediction and that's a great goal to have for sufficient assumption questions. If you have a really strong prediction, you are much less likely to get lost in all the choices. You might be able to quickly scan and just find your match on test day within seconds, and that would be ideal. For completion's sake, though, let's go through each choice, one-by-one, in full. A, whatever memorization is necessary can be accomplished as easily without computers as with them. This choice doesn't connect the gap in the argument. The part of the argument dealing with memorization isn't even part of the main argument. It's just a side note, like a concession about one thing that computers are good for. We need to connect the ideas of higher intellectual functions and having an impact on education. B, requiring memorization in appreciable amounts tends to thwart development of higher intellectual functions in students. This is like A in that it focuses on requiring memorization, but we don't care about memorization. We could seriously cut that entire sentence about memorization from the passage and it wouldn't change the argument's main structure, so this choice is irrelevant and we can cut it. C, successful memorization of relevant facts is a necessary precondition for the development of higher intellectual functions in students. Once again, I am so glad we have a strong prediction because our prediction has nothing to do with memorization and so far, three of the choices have opened with memorization. It may be true that memorization is necessary for development of higher intellectual functions in students, but we're still told in the passage that computers can't help students with higher intellectual functions. And if they can't help, they can't help, so choice C doesn't give us anything that ties the argument together. D, many students become familiar with computers before encountering them at school. This choice doesn't do anything for us in terms of guaranteeing that the conclusion will follow from its support. If many students are familiar with computers before encountering them at school, but computers can't help students with higher intellectual functions, which is what we're told, then maybe computers can have an impact on education and maybe they can't. Familiarity with computers isn't relevant to this argument, we need to tie in higher intellectual functions. E, having an appreciable impact on education involves affecting the higher intellectual functions of students. This is a match for our prediction. You might've been surprised by the way it was worded. We said our prediction was that if something can't help students with higher intellectual functioning, then that something can't have a big impact on education. Choice C is actually the logically equivalent statement. If something does have a big impact on education, then that something must involve affecting the higher intellectual functions of students. That is a match, and just in case you can't see it, logically equivalent statements are like this. If I'm at the beach, then I must have found my sunscreen is logically equivalent to, if I didn't find my sunscreen, then I'm not at the beach. To test choice E, try adding it to the evidence from the passage and see if it leads to the same conclusion. This choice tells us that appreciable impact on education involves affecting higher intellectual functions and then the support from the passage told us that machines can't help students with higher intellectual functions. If we combine these two statements, what could we definitely conclude? Machines can't have an appreciable impact on education and that is the conclusion from the passage. That means that we have found the assumption that guarantees the conclusion to follow from its evidence. So, to recap, for sufficient assumption questions, it's very, very helpful if you can phrase the conclusion and the evidence simply and accurately on test day. Then you can look for the gap between the evidence and the conclusion and make a prediction for what connects the gap, and that connection is what ensures that the conclusion follows logically. If you wanna test the choice, you can add it to the passage evidence and ask yourself what the implication is when you add the choice to the evidence. If that implication matches the passage's conclusion, then you have the answer. Watch out for choices that aren't relevant to the main argument. In this example, we saw three choices that dealt with memorization and that was part of the passage that didn't even contribute to the main structure. So, it's really important to stay sharp with identifying your main conclusion and the main evidence and look for the gap that the answer will close.