8.2 If/Then And Must/May Logic

Conditions Create Results

An if/then statement is the cleanest way to organize a rule. The "if" clause states the condition; the "then" clause states the result that follows when the condition is met. Rewriting policy-style wording into this structure makes deduction far more reliable, because it forces the condition and the result into separate boxes.

Take a CJBAT-style policy: "An inmate may receive a contact visit only if the inmate has had no disciplinary report in the past 30 days." In if/then form: if the inmate had a disciplinary report in the past 30 days, then the inmate may not have a contact visit. The condition is the recent disciplinary report; the result is the loss of the contact visit.

The Four Conditional Patterns

From a single rule "if A, then B," there are four things you might conclude. Only two are valid.

The two invalid patterns are where most test-takers lose points. Affirming the consequent means seeing the result and assuming the condition caused it — but other conditions could produce the same result. Denying the antecedent means assuming that without the condition the result can't happen — but the rule never said the condition was the only path.

Worked example of the trap. Rule: "If an alarm is triggered, dispatch sends a unit." Fact: "A unit was sent." Invalid conclusion: "Therefore an alarm was triggered." Wrong — a unit might be sent for a 911 call, a traffic stop, or a welfare check. The result does not prove the condition.

The contrapositive, by contrast, is always safe. From the same rule, if no unit was sent, you may validly conclude no alarm was triggered — because if an alarm had been triggered, the rule guarantees a unit would have gone.

Must Versus May, And Quantifiers

"Must" means the conclusion is required; "may" means it is permitted or possible. If the facts satisfy a rule that says a result "must" follow, that result is certain. If a fact is only compatible with a result, the result "may" be true but is not proven. The test rewards picking the certain conclusion over the merely possible one.

Quantifier words reshape what a rule supports:

• All / every — the rule applies to each member with no exception.
• Some / at least one — the rule applies to one or more, but not necessarily all; you cannot conclude "all."
• Only / only if — names a required condition; the result cannot occur without it.
• None / no — a flat prohibition; any answer permitting it conflicts.
• Or — at least one of the listed conditions suffices (check whether the rule means either, or both).

Worked example with a quantifier. Rule: "Only recruits who pass the swim assessment may begin water-rescue training." Fact: "Recruit Diaz has not passed the swim assessment." Because "only" makes passing a required condition, the necessary conclusion is that Recruit Diaz may not begin water-rescue training. An answer saying "Diaz must retake the swim assessment" overreaches — the rule blocks the training but says nothing about a mandatory retake.

Use this if/then checklist on every conditional item:

• Underline the condition (after "if") and the result (after "then").
• Apply only the two valid moves: affirm the condition, or deny the result.
• Never affirm the result or deny the condition.
• Treat "must" as certain and "may" as merely possible.
• Read quantifiers (all, some, only, none, or) exactly as written.

If/then practice is not about memorizing legal language; it is a disciplined way to read any rule. Because the CJBAT is multiple choice, the choices typically include one conclusion that must follow and several that only sound plausible. Translate the rule, run the valid moves, and pick the necessary conclusion.

Chaining Conditionals And Reading Compound Rules

Real policies often stack conditionals so that one rule's result becomes another rule's condition. When two if/then statements share a term, you can chain them: from "if A then B" and "if B then C," it validly follows that "if A then C." This is the transitive move, and it is exactly how a deductive prompt can lead you several steps from a single starting fact.

Worked example. Rule 1: "If a recruit is tardy, the recruit receives a counseling note." Rule 2: "If a recruit receives a counseling note, the recruit must meet with the academy coordinator." Fact: "Recruit Bell was tardy." Chaining: tardy triggers a counseling note, and a counseling note triggers a coordinator meeting, so the forced conclusion is that Recruit Bell must meet with the academy coordinator. Note what you may not conclude: that the meeting changes Bell's standing, or that Bell will be dismissed — those outcomes are outside both rules.

Compound conditions also demand care. A rule reading "if A and B, then C" fires only when both A and B are present; one alone is not enough. A rule reading "if A or B, then C" fires when at least one of A or B is present. Mixing these up is a frequent error.

Finally, watch negation. A rule that says "a candidate who is not on the approved roster may not test" is still a precise conditional: not-on-roster triggers cannot-test. Its valid contrapositive is that anyone who did test must have been on the roster. Negative rules are just as bindable as positive ones — read them slowly, because a single 'not' flips the entire conclusion. Translate every rule into clean if/then form, chain where terms connect, respect 'and' versus 'or,' and the compound items lose most of their difficulty.