How to diagram conditions

[MinahK651]

I have the ebook and in PT14, S4, Q9

Since anyone who supports the new tax plan has no chance of being elected, and anyone who
truly understands economics would not support the tax plan, only someone who truly under-
stands economics would have any chance of being elected.

The last part of this question is diagrams in condition as:

Electable -> understand economics.

I do not understand why it is not
Understand economics -> electable.

How do you know which statement to put in the sufficient position?

[ohthatpatrick]

You have two main options:
1. Use a real-world example which you know to be true that uses the same keyword

2. Memorize how these recurring keywords work (whether they indicate left side or right side ideas)

"only someone who truly understands economics would have any chance of being elected."

OPTION 1
What's a real world example which uses "only"?

Only men play in the NFL.

Would that look like
MAN --> PLAY IN NFL
or
PLAY IN NFL --> MAN

It would look like the 2nd option. The first option says "if you're a man, then we're certain you play in the NFL".

So apparently in a sentence that says "Only X's are Y", we should end up with "If Y, then X"

OPTION 2
"only someone who truly understands economics would have any chance of being elected."

"only" = right side idea, so "someone who truly understand econ" goes on the right side

------------> truly understands econ

That means I put the other idea on the left side
"chance of being elected ---> truly understands econ"


===========================

I favor OPTION 2, because it's quicker and more brainless.

LEFT SIDE WORDS: any, each, every, all, if, when, whenever, the only
RIGHT SIDE WORDS: only, only if, requires, ensures, must, depends on, implies, guarantees, always leads to

"IF NOT": unless, without, until

No A's are B's = All A's are ~B = A --> ~B

[MinahK651]

that clarifies it!
thanks a lot!