2.3 True, False and Indeterminable

Three logical outcomes, not three confidence levels

For each Critical Thinking conclusion, the official directions offer exactly three responses:

• True: the conclusion can be inferred from the facts.
• False: the conclusion is contrary to the facts.
• Indeterminable: the facts are insufficient to decide whether the conclusion is true or false.

Do not translate these into probably true, probably false, and unsure. A plausible conclusion is still Indeterminable when the passage does not guarantee it. An unusual conclusion is True when the passage forces it. The content may not reflect real Secret Service policy, and no prior subject knowledge is required.

The two-world test

When uncertain, imagine two possible worlds that both obey every passage fact. If the proposed conclusion is true in one and false in the other, the conclusion is Indeterminable.

Facts:

• All vehicles in Lane A were inspected.
• Van 3 was inspected.

Conclusion: Van 3 was in Lane A.

World one puts Van 3 in Lane A. World two puts it in Lane B, where vehicles may also be inspected. Both worlds satisfy the facts, so the conclusion is Indeterminable. Calling it True would reverse "Lane A → inspected." Calling it False would assume that only Lane A vehicles can be inspected.

When a conclusion is True

A conclusion is True when denying it would violate at least one passage fact. Common routes are:

1. Direct restatement: The passage says Patel arrived before 0900; the conclusion says Patel did not arrive at or after 0900.
2. Forward chain: All A are B, all B are C, and X is A; therefore X is C.
3. Contrapositive: P implies Q and Q did not occur; therefore P did not occur.
4. Guaranteed overlap: Some A are B; therefore some B are A.
5. Guaranteed exclusion: No A are B and X is A; therefore X is not B.

The conclusion need not repeat the passage's wording, but every step must be necessary.

When a conclusion is False

A conclusion is False only when the passage rules it out. Look for direct opposites, impossible category overlap, or an event sequence that cannot fit.

Facts:

• No red badges are temporary badges.
• Badge R is red.

Conclusion: Badge R is temporary.

The conclusion is False because the facts establish both membership in red badges and complete separation from temporary badges.

Now consider "Badge R is permanent." That may feel like the natural opposite of temporary, but the passage never says that all non-temporary badges are permanent. Other types could exist. The answer is Indeterminable. This contrast captures the core distinction: False needs disproof; Indeterminable needs only an open possibility.

Missing information patterns

Select Indeterminable when a conclusion depends on:

• A reversed all or if-then relationship.
• A claim about the remainder after a some statement.
• A comparison that the passage never makes.
• An exact number derived from vague quantities such as many or few.
• A cause inferred from a sequence of events.
• A real-world rule, job practice, or definition absent from the passage.
• An assumption that named examples are the only examples.

Worked mini-passage

Facts:

• Every afternoon courier uses Entrance D.
• No person using Entrance D carries a visitor badge.
• Some couriers are afternoon couriers.
• Kim carries a visitor badge.

Evaluate four conclusions:

1. Some couriers do not carry visitor badges — True. The known afternoon couriers use D, and no D user carries a visitor badge.
2. Kim is not an afternoon courier — True. An afternoon courier would use D and therefore could not carry a visitor badge.
3. Kim is not a courier — Indeterminable. Kim cannot be an afternoon courier, but other couriers may exist.
4. All couriers use Entrance D — Indeterminable. Only afternoon couriers are assigned to D.

Notice that True and False are about logical necessity, not whether an examiner thinks the conclusion is sensible.

Final classification questions

Ask in order:

1. Can I prove the conclusion with a direct fact, valid arrow, overlap, or exclusion? If yes, True.
2. Can I prove the opposite with those same tools? If yes, False.
3. If neither side is proved, can both possibilities coexist with the passage? If yes, Indeterminable.

This routine prevents the most common error: turning silence into contradiction.

Evidence label

On scratch material, mark each decision with a short reason such as stated, chain, contradicted, or missing link. A reason label makes review faster and keeps uncertainty from masquerading as contradiction.