Oh, Yes: How to Diagram “No” Statements on the LSAT
- Aug 01, 2014
- Advice on Logical Reasoning, LSAT
With a scurry and dash, a dodge and a slash, the No Ninja appears on the scene. Or: There She Blows, No Torpedoes the Necessary. Maybe, I don’t know…Calamatizes the Consequent, Foils the Following, what have you.
All of these mnemonics illustrate a very simple but highly effective tool for diagramming “No” statements on the LSAT. These are common conditionals, and they can come in many forms:
· No mathletes have girlfriends.
· None of the above are correct.
· Neither of them are getting her number.
· No one who dislikes Star Wars can be my friend.
The important thing to note here is that each of these statements posit that there is no overlap between the two groups. The group of “Mathletes” does not overlap with the group of “having a girlfriend,” for example.
Thus, to diagram, we show that if you are a member of one of these groups, you are not a member of the other. Just that simple. If you are in group A, then that means you are necessarily not in group B.
A —> not B
the contrapositive, of course, is
B —> not A
Going back to picking on mathletes, we would say that
M —> no GF
and the contrapositive would be
GF —> not M
Meaning that if you are a mathlete, then you don’t have a girlfriend; if you have a girlfriend, you cannot be a mathlete.
We refer to this procedure as the “No Torpedo” and “No Ninja” to reinforce the idea that if you belong to the sufficient group then you “torpedo” or “slash” the necessary group. If you too coo’ for punny memory tricks, remember simply that because the groups do not overlap, belonging to one is sufficient to conclude that you necessarily cannot belong to the other.
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