Why (A) is right: necessary vs. sufficient condition
A Flaw explanation from our free library. The question below is original, written for this page. Then the full breakdown: why the right answer is right, and why each wrong answer is wrong.
The question
No one can build a successful business without taking risks. So anyone who takes a big risk will build a successful business.
Which one of the following most accurately describes the flaw in the argument?
- It treats a necessary condition for success as though it were enough to guarantee success. Correct
- It confuses two different meanings of the word 'risk.'
- It assumes that every successful business took exactly the same risks.
- It overlooks the fact that some people build successful businesses without taking any risk.
- It draws a conclusion about individuals from a claim about businesses in general.
Why (A) is correct
"No one can succeed without taking risks" means risk is required. Required is not the same as enough. Oxygen is required for a fire, but oxygen alone does not start one.
The argument needs the stronger claim that risk guarantees success, and the premise does not give it. Choice (A) states the exact error: a condition that is necessary got treated as if it were sufficient.
Why the wrong answers are wrong
(B) Out of scope
The argument uses 'risk' in one consistent sense. There is no shift in meaning to exploit, so this answer describes a flaw that is not there.
(C) Misstates the argument
The argument says nothing about which risks or how many. It only says risk is required. This answer attacks a stronger claim than the one made.
(D) Denies a premise
On the LSAT you accept the premises as true. The premise says risk is required. An answer that contradicts a premise cannot describe the flaw in the reasoning from those premises.
(E) Misses the reasoning move
The argument moves from one claim about business builders to another claim about business builders. The error is the necessary/sufficient mix-up, not a part-to-whole jump.
Last updated October 12, 2026