LSAT: Logical Indicators

To practice identifying logical indicators and deriving the underlying logic

“If” - Create a conditional statement and identify sufficient and necessary conditions.

If is a sufficient condition indicator.

If X —> Y

/Y —> /X

X is sufficient, Y is necessary

“When” - Create a conditional statement and identify sufficient and necessary conditions.

When is a sufficient condition indicator.

When X —> Y

/Y —> /X

X is sufficient, Y is necessary

“Where” - Create a conditional statement and identify sufficient and necessary conditions.

Where is a sufficient condition indicator.

Where X —> Y

/Y —> /X

X is sufficient, Y is necessary

“All” - Create a conditional statement and identify sufficient and necessary conditions.

All is a sufficient condition indicator.
All X —> Y

/Y —> /X

X is sufficient, Y is necessary

“Every” - Create a conditional statement and identify sufficient and necessary conditions.

Every is a sufficient condition indicator.

X —> Y

/Y —> /X

X is sufficient, Y is necessary

“Any” - Create a conditional statement and identify sufficient and necessary conditions.

Any is a sufficient condition indicator.

X —> Y

/Y —> /X

X is sufficient, Y is necessary

“The only” - Create a conditional statement and identify sufficient and necessary conditions.

The only is a sufficient condition indicator.

X —> Y

/Y —> /X

X is sufficient, Y is necessary

“Only” - Create a conditional statement and identify sufficient and necessary conditions.

Only is a necessary condition indicator

Only Y has X

X —> Y

/Y —> X

“Only if” - Create a conditional statement and identify sufficient and necessary conditions.

Only if is a necessary condition indicator

Only if Y does X

X —> Y

/Y —> X

“Only when” - Create a conditional statement and identify sufficient and necessary conditions.

Only when is a necessary condition indicator

Only when Y does X occur

X —> Y

/Y —> X

“Only where” - Create a conditional statement and identify sufficient and necessary conditions.

Only where is a necessary condition indicator

Only where Y does X

X —> Y

/Y —> X

“Always” - Create a conditional statement and identify sufficient and necessary conditions.

Always is a necessary condition indicator

X always has Y

X —> Y

/Y —> X

“Must” - Create a conditional statement and identify sufficient and necessary conditions.

Must is a necessary condition indicator

X must have Y

X —> Y

/Y —> X

“or - Create a conditional statement and identify sufficient and necessary conditions.

Or is a negative sufficient indicator. You pick either idea, then negate that idea, then make that idea the sufficient condition.

X or Y

EITHER:

/X —> Y | /Y —> X

OR

/Y —> X | /X —> Y

“unless” - Create a conditional statement and identify sufficient and necessary conditions.

Unless is a negative sufficient indicator.

Unless X, Y

EITHER:

/X —> Y | /Y —> X

OR

/Y —> X | /X —> Y

“until” - Create a conditional statement and identify sufficient and necessary conditions.

Until is a negative sufficient indicator.

Until X, Y

EITHER:

/X —> Y | /Y —> X

OR

/Y —> X | /X —> Y

“Without” - Create a conditional statement and identify sufficient and necessary conditions.

Without is a negative sufficient indicator.

Without X, Y

EITHER:

/X —> Y | /Y —> X

OR

/Y —> X | /X —> Y

“No”

No is a negative necessary indicator.

No X have Y

EITHER:

Y —> /X | X —> /Y

OR

X —> /Y | Y —> /X

“None”

None is a negative necessary indicator.

No X have Y

EITHER:

Y —> /X | X —> /Y

OR

X —> /Y | Y —> /X

“Not both”

Not both is a negative necessary indicator.

No X have Y

EITHER:

Y —> /X | X —> /Y

OR

X —> /Y | Y —> /X

“Cannot”

Cannot is a negative necessary indicator.

No X have Y

EITHER:

Y —> /X | X —> /Y

OR

X —> /Y | Y —> /X

List and explain sufficient condition indicators

if, when, where, all, every, any, the only
The idea immediately following the conditional indicator is the sufficient condition.

List and explain necessary condition indicators

only, only if, only when, only where, always, must
The idea immediately following the conditional indicator is the necessary condition.

List and explain negative sufficient indicators

or, unless, until, without
Pick either idea, then negate that idea, then make that idea the sufficient condition. The other idea is the necessary condition.

List and explain negative necessary indicators

no, none, not both, cannot
You pick either idea, then negate that idea, then make that idea the necessary condition. The other idea is the sufficient condition.

Explain bi-conditionals. List indicators.

Conditions mutually dependent; necessary and sufficient for each other. They are either both true or both false.

If and only if
If but only if
Then and only then
Or... but not both
If... then... but not otherwise