Logical Reasoning Chapter 3

What are the most important words in an argument called?

Power Players — MUST, CANNOT, COULD, NOT NECESSARILY, and their synonyms.

What are the Certainty Power Players?

Must and Cannot.

What are the Possibility Power Players?

Could and Not Necessarily.

Why are Power Players important?

Power players are very important because of the difference in how hard it is to prove conclusions with each of the power players.

How hard is it to prove a Must conclusion?

Must is tough to prove and easy to attack. To prove Must, you need some powerful premises to back you up. Must has a huge burden of proof.

How hard is it to prove a Cannot conclusion?

Cannot is difficult to prove and easy to attack. To prove cannot, you need powerful premises. Cannot has a massive burden of proof as well.

How hard is it to prove a Could conclusion?

Could is much easier to prove and harder to attack. To prove Could, you just need premises that allow the could conclusions to be a possibility.

How hard is it to prove a Not Necessarily conclusion?

Not Necessarily is also easy to prove and harder to attack. Loopholes are going to have to be very strong to invalidate this conclusion.

What happens if changing one word makes the conclusion easier or harder to prove?

You’re dealing with strong or loaded language — a Power Player.

What is the difference between content and Power Players?

Content is replaceable and topic-specific; Power Players control reasoning strength.

Why shouldn't you focus only on content in an argument?

Because the reasoning strength comes from Power Players, not the story.

What are the strongest and most straightforward Power Players?

Must and Cannot.

How do you treat a sentence without words showing certainty or uncertainty?

Treat it as a statement of certainty.

What does 'Must' mean on the LSAT?

100% certain — no exceptions, completely true as stated.

What does 'Cannot' mean on the LSAT?

0% possible — totally impossible, not even a small chance.

What makes Possibility Power Players different from Certainty ones?

They cover a range of likelihoods, not a fixed level.

Why do 'Could' and 'Not Necessarily' often cause confusion?

Because they both allow for uncertainty. "Could" means something might happen but isn’t required to, and "Not Necessarily" means something isn’t guaranteed to happen. They differ at the extremes.

How do 'Could' and 'Not Necessarily' differ?

Could includes everything from 1% to 100%, but not 0%. Not necessarily includes everything from 0% to 99%, but not 100%.

What does 'Could' mean in argument terms?

Not impossible — as long as there's any chance, it's valid.

What does 'Not Necessarily' mean in argument terms?

Not 100% — might or might not be true.

When is 'Not Necessarily' often used in arguments?

It’s often used to challenge or weaken someone else argument, especially when that person is making a Must claim. You are claiming that whatever someone else says has to be true isn't actually proven.

How does 'Not Necessarily' appear in LSAT stimuli?

Not necessary often appears in stimuli that begin with phrases like “some scientists,” “some critics” or “some people believe...” When the author disagrees with these views, they may respond by saying the argument is not necessarily true. This shows the author is pushing back without making a strong or absolute claim.

What are Certainty Premises?

Must and Cannot Premises — strong evidence.

What are Certainty Conclusions?

Must and Cannot Conclusions — hard to prove.

What are Possibility Premises?

Could and Not Necessarily Premises — weak evidence.

What are Possibility Conclusions?

Could and Not Necessarily Conclusions — easy to prove.

What does every argument try to do, regardless of conclusion type?

Prove the conclusion is definitely true, even for possibility claims.

When are Certainty Conclusions valid?