Inference and Implication

Inference questions are where this subtest separates people, because every other type has an answer written down and this one does not.

The trap is specific: the wrong answers are plausible. They are things a sensible person might conclude. And a question asking what the passage "suggests" or "implies" feels like an invitation to think, when it is actually a very narrow demand.

Forced against consistent

The motor pool keeps two spare alternators on hand at all times. When one is fitted to a vehicle, a replacement is ordered the same day.

Forced: the number of spares on hand drops below two only briefly. The passage says two at all times and same-day ordering, so this follows.

Merely consistent: alternators fail often. Maybe they do - the policy would make sense either way, and a cautious unit might hold spares for a part that rarely fails. Nothing in the passage establishes a failure rate.

Both statements sound reasonable. Only the first is supported.

The test is not "could this be true?" It is "does the passage make this true?"

Take the smallest step

The correct inference is usually one short move from a stated fact.

Fuel for the generators is delivered weekly. During the storm the road was closed for nine days.

One step: the generators went without a scheduled delivery. That follows directly from weekly delivery and a nine-day closure.

Two steps, and now you are guessing: the generators ran out of fuel. Maybe there was a reserve. Maybe they were not running. The passage says nothing about consumption.

If an answer requires you to supply a fact the passage did not give, it is too far. Ask what extra assumption the choice needs. If it needs one, it is wrong.

Name the sentence

The practical discipline.

For every inference you are about to pick, point at the line it rests on. Not the general sense of the passage; a specific sentence or two.

If you find yourself saying "well, it's implied by the whole thing", stop. That is usually the feeling of having reasoned past the evidence.

How wrong inferences are built

The plausible extension. True of the world, consistent with the passage, not established by it. The most common shape.

The overreach. Right direction, too strong. The passage supports "sometimes" and the choice says "always", or the passage supports "contributed to" and the choice says "caused".

The reversal. Takes a real relationship in the passage and runs it backward. If the passage says heat causes expansion, a choice saying expansion causes heat uses every word correctly and is wrong.

The near-restatement. Something the passage actually states outright, offered as an inference. It is not wrong in substance, but if the question asks what the passage implies and a choice simply repeats a line, look for the choice that takes a step. Read carefully here, because sometimes the stated thing really is the intended answer - the wording of the question decides it.

Working one through

Aircraft de-icing fluid is applied heated and loses effectiveness as it cools. The interval during which the treated surface stays clear is called the holdover time, and it shortens in heavy precipitation. Crews recheck the wings if the holdover time expires before takeoff.

It can be inferred from the passage that

(A) de-icing fluid is expensive (B) a delay before takeoff may require a second application (C) heavy precipitation makes flight impossible (D) heated fluid is more effective than cold fluid at removing existing ice

Check each against the text.

(A) Outside the passage. Nothing about cost. Plausible, unsupported.

(B) Holdover time can expire before takeoff, and crews recheck when it does. A delay makes expiry more likely, and rechecking implies possible re-treatment. One short step from two stated facts. This is the answer.

(C) Overreach. The passage says heavy precipitation shortens holdover time, not that it prevents flight.

(D) Reversal and extension. The passage says the fluid is applied heated and loses effectiveness as it cools, which is about the treated surface staying clear, not a comparison of removal ability. It also requires the assumption that effectiveness means removal.

(B).

What you can skip

• Outside knowledge. An inference that needs facts from outside the passage is wrong on this test, however true it is. Knowing the subject well can actively mislead.

Where people lose points

Choosing the most interesting conclusion. The correct inference is usually dull, because it is close to what was said.

Supplying a fact from your own knowledge to make a choice work.

Missing an absolute that turns a supported idea into an unsupported one.

Accepting a reversal because all the words are from the passage.

Treating "suggests" as permission to speculate. It is not; it means the conclusion is forced without being stated.

Work one in under a minute

Every tool leaving the cage is signed out against a numbered tag, and the tag stays in the empty slot until the tool is returned. At the end of the shift the supervisor walks the cage and notes any slot still holding a tag.

It can be inferred that the walk at the end of the shift is intended to

(A) count the total number of tools (B) identify tools not yet returned (C) check that tools are undamaged (D) confirm the tags are numbered correctly

A tag sits in a slot only while the tool is out, so a slot still holding a tag at the end of the shift means that tool has not come back.

(B). One step from two stated facts.

(A), (C) and (D) each require something the passage never mentions: a count, a condition check, an audit of the tags themselves. All three are things a supervisor might sensibly do, which is exactly the trap.

Where this leads

The same discipline - name the line, take the smallest step - is what separates a supported argument from an unsupported one, which is the next lesson.