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A Necessary Skill for Acing the LSAT

  • by Robert Seaney
  • Aug 09, 2014
  • Advice on Logical Reasoning, LSAT

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In case you hadn’t already noticed, understanding and manipulating conditional statements is key to success on Logical Reasoning questions. If you don’t master this skill, then your target score will elude you (ya see what I did there?). 

In our ongoing series we’ve covered many of the trickier types of conditional statements, but today we’re going to bring it back to basics with identifying the necessary condition through what we at Blueprint call “indicator words.” 

This skill is fundamental in the sense that it’s necessary (dry puns abound) in order to get your diagramming off the ground. If the necessary and sufficient conditions are misinterpreted and thus diagrammed incorrectly, transitive chains will be missed, sufficient stacks will go unnoticed, etc., etc. Most common, perhaps, is confusing which of two statements in a sentence is the sufficient and which is the necessary. For example:

“If you clap your hands, Spot will bark.”

This is pretty straightforward. As many of you will have noticed, we have a sufficient condition followed by a necessary, and our diagram looks like this:

CH —> SB (Clap Hands —> Spot Barks)

But what about when the structure is not so clear? Consider the following:

“Spot will bark if you clap your hands.”

Some students are inclined to think that this is also a sufficient condition followed by a necessary, and diagram it as such:



SB —> CH (Spot Barks —> Clap Hands)

This is, of course, incorrect. This diagram is actually the converse of the sentence given, and means, quite absurdly, that “If Spot barks, then you clap your hands.” Spot barks at lots of things — shadows, mailmen, that fine poodle down the street — so we know that this is not a proper representation of the original conditional statement. This sort of confusion can throw a question off track entirely, so to avoid it we look for indicator words.


“Then” is the canon of necessary indicators, to which we compare all others and below which all others are situated. Lucky for us, it comes up quite often on the LSAT as “If the iron is hot, then don’t touch it,” or “if you lose your dentures then you must eat soup.” Other common terms include “requires,” “necessitates,” and “must.”

While there are some relatively obscure terms that have the same meaning (“precipitates” and “yields,” for example), the LSAC’s goal is to beat you with logic, not with vocabulary. Thus, rarely will you see a question lexiconically obfuscated so as to be inimical. Focus instead on finding the referent of the necessary indicator, and thereby accurately identifying and diagramming the conditional.

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