LSAT Necessary and Sufficient Assumptions 4

Question 1

An argument has premises P1 and P2 and conclusion C. A sufficient assumption SA is one where:

Accepted Answer

P1 + P2 + SA → C

Answer

A sufficient assumption works together with the existing premises to guarantee the conclusion—it fills the gap that makes the argument valid.

Question 2

Which scenario demonstrates a necessary but NOT sufficient assumption?

Accepted Answer

An assumption whose negation destroys the argument but whose affirmation does not alone guarantee the conclusion

Answer

A necessary assumption is required for the argument but may not be enough on its own to make the conclusion certain.

Question 3

Argument: 'Organic farming avoids synthetic pesticides. Avoiding synthetic pesticides benefits local ecosystems. The Hendersons farm organically. Therefore, the Hendersons benefit local ecosystems.' This argument:

Accepted Answer

Is already deductively valid with no unstated assumptions needed

Answer

The premises chain together logically to yield the conclusion, making this a valid deductive argument with no hidden gaps.

Question 4

A student negates an assumption and finds the argument becomes 'significantly weaker but not completely destroyed.' This suggests the assumption is:

Accepted Answer

Probably a strengthener, not a necessary assumption

Answer

A necessary assumption, when negated, must completely undermine the argument—if it only weakens it, the statement is more like a strengthener.

Question 5

Argument: 'Violent video games desensitize players to violence. Desensitization to violence increases aggressive behavior. Therefore, playing violent video games increases aggressive behavior.' A necessary assumption is:

Accepted Answer

The desensitization caused by video games is the same type that increases aggression

Answer

The argument links two types of desensitization, so it must assume they are the same or equivalent for the chain to hold.

LSAT - Law School Admission Test Practice Test

LSAT - Law School Admission Test Practice Test

LSAT Necessary and Sufficient Assumptions 4