LSAT 12 - Section 4 - Question 20

This is a Sufficient Assumption (SA) question and we know this because of the question stem: “conclusion is properly drawn from the premises given if which one of the following is true...”

Sufficient assumption questions tend to be very formal. We’re looking for a rule that would validate the conclusion, specifically by bridging the premise and conclusion through the rule. Not only are we extrapolating the rule from our argument, but we’re also using that rule to render the argument “valid.” The way to prephrase our answer choice is by tying our premises and conclusion together into a rule: “If [premise] → then [conclusion].” Sometimes, a rule is not always helpful. Recognition of what the gap is might be a more useful prephrase.

The first sentence is a comparison between the pull stroke between an S-shaped rake and a straight-handle rake. The S-shaped rake will reduce compression on the spine to 1/5 of what is it with the latter.

The next sentence starts with a “however” which makes me think there is some information that is different or runs contrary to the information presented before in some way (pivoting). Reading on, we learn that on the push stroke, the s-shaped rake exerts 5x more pressure than the straight rake.

In the next sentence, we learned that the compression in the pull/push for the straight rake is not dangerous, but it is above the danger lever for the s-shaped rake. So far all of this is just information/premises. The next sentence begins with “therefore,” and states that straight rakes are better than s-shaped rakes for minimizing the risk of spinal injury. This is our conclusion.

What is the gap here? Well, jumping from compression stress injuries on the spine to all injuries on the spine. And also, the statistics of risk are equal: X being 5 times Y and Y being 1/5 of X is equal. Why should we prefer a straight-handled rake if the risk of injury for pulling in one and pushing in the other is the same? Our rule needs to relate stress caused by pushing (because that’s the one where s-shaped rakes are worse) to factors associated with all spinal injuries when raking. Not only that, but it needs to explicitly say that the two go hand in hand, or compression related to the push (and not pull) stroke is one of the most important factors in all spinal injuries caused by raking.

Correct Answer Choice (A) This answer choice is relating compression from pushing and spinal injuries in a causal relationship by saying that compression stress from pushing rakes is the only cause of spinal injuries from raking. So, of all the injuries that happen with raking, spinal injuries are only caused by compression stress from pushing the rake, which means that we can conclude that straight rakes are better for minimizing spinal injuries in general.

Answer Choice (B) This is not the correct answer. It’s not relevant to making our conclusion valid – sure, a gardener can still get spinal injuries by using even a straight-handled rake. If we plug this back into our stimulus, it doesn’t really do anything.

Answer Choice (C) This is describing what is happening with the redesign’s flaw. If this was a principle question, this would be a great answer choice. However, this is an SA question and our conclusion has nothing to do with a redesign having no gain in efficiency. We’re making a judgment claim on which rake is better as it relates to a specific category of injuries.

Answer Choice (D) This is basically saying that some strokes have to be pull strokes, which means that there is some risk of compression injury with a straight handle. This attempts to weaken our answer choice but fails because some risk while raking is compatible with our conclusion (it’s about lowering risk, not eliminating it).

Answer Choice (E) This is pointless to our argument. We’re trying to say that one is better than the other, not introduce a third option.