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 understands economics would have any chance of being elected.
Conclusion
Only someone who truly understands economics would have any chance of being elected.
Evidence (since, and)
Anyone who supports the new tax plan has no chance of being elected.
Anyone who truly understand economics would not support the tax plan.
Evaluate
Whenever we’re doing Flaw and we see Conditional Logic indicator words (in this case, “anyone / anyone / only”), we should be on the lookout for the author reading a conditional logic rule illegally, backwards or negated. This is the #1 famous flaw, confusing Necessary vs. Sufficient.
Here are the two premises:
Support → no chance of tax plan being elected
Support → don’t truly understand tax plan economics
They don’t chain together, since they both start from the same trigger. The conclusion is acting like they chain together, though:
don’t truly → no chance of understand econ being elected
How do we know which side of that is messed up? Well, we have “no chance of being elected” on the right of an arrow, so that one is fine. We do not have “don’t truly understand econ” on the left of an arrow, so that one is being messed up. The author is reversing that conditional. She thinks our two premises were like this:
don’t truly → Support understand econ tax plan
Support → no chance of tax plan being elected
Those two conditionals would chain together to derive the conclusion the author drew. So the author did indeed commit a Necessary vs. Sufficient error. We can say that “don’t truly understand economics” was a condition required of supporting the tax plan, but the author is acting as though it’s sufficient to prove you support the tax plan.
Conversationally, we could think,
The argument said that in order to have a chance of being elected, you have to oppose the new tax plan. But who says you need to understand econ in order to understand the new tax plan? Maybe someone could not understand economics, but they still oppose the tax plan and thus have a chance of being elected.
Goal
If this were regular ol’ Flaw, then we would look for an answer making the formal complaint that the author mixed up necessary and sufficient when it comes to the rule about “truly understand economics”, or look for the informal complaint that it’s possible that someone opposes the tax plan, even though they don’t understand economics.
But since this question stem is already pre-loaded with “fails to consider” Weaken language, we can expect the latter.