3.6 RC Inference, Assumptions & Author's Perspective

RC Inference, Assumptions & Author's Perspective

Quick Answer: Inference questions ask what must be true if the passage is true, not what the passage states. Assumption questions ask what unstated premise the author's argument depends on. ETS tests both by rewarding test-takers who can reason from incomplete data, identify the author's assumptions and perspective, and consider alternative explanations - all without bringing in outside knowledge.

What Counts as an Inference on the GRE

An inference is a statement that must be true if the passage is true. It is not a prediction, not a speculation, and not a fact you happen to know. ETS phrasing for inference questions includes:

• "It can be inferred from the passage that..."
• "The passage suggests that..."
• "Which of the following, if true, is most strongly supported by the passage?"
• "The author of the passage would be most likely to agree with which of the following statements?"

The right answer is almost always a modest claim. ETS inferences tend to use hedged language: probably, tend to, in some cases, more likely. Answers that use always, never, only, all, or impossible are usually wrong unless the passage uses equally strong language.

The Inference Falsification Test

For each choice, ask: "If the passage is true, must this also be true?" If you can construct a scenario where the passage is true but the choice is false, eliminate the choice. The correct answer is the one you cannot falsify.

Identifying Assumptions

An assumption is an unstated premise the argument needs in order to be valid. ETS tests assumptions directly ("the argument assumes...") and indirectly through strengthen and weaken questions.

Three assumption types appear repeatedly:

1. Causal assumptions. The author claims X caused Y; the assumption is that no alternative cause exists. Weaken by offering an alternative cause; strengthen by ruling one out.
2. Representativeness assumptions. The author generalizes from a sample; the assumption is that the sample is representative. Weaken by showing the sample is unusual.
3. Definitional or equivalence assumptions. The author treats two terms as interchangeable; the assumption is that they really are. Weaken by distinguishing them.

When a question asks what the author "takes for granted," look for the bridge between the evidence and the conclusion. The author almost never states that bridge, which is exactly why it is an assumption.

Author's Perspective: Tone and Attitude

GRE authors rarely announce their opinions. You infer attitude from verb choice, adjective choice, and the structure of the argument:

Tone questions ask for a one- or two-word characterization - skeptical, cautious, enthusiastic, objective, critical. The right answer must be supported by specific words in the passage; never pick a tone because it "feels right."

Distinguishing Strong Commitment from Speculation

ETS explicitly lists this skill. Authors signal commitment with modality:

• Strong commitment: demonstrates, establishes, shows, is, must
• Moderate commitment: suggests, indicates, supports, likely
• Speculative: might, could, may, possibly, allegedly
• Reported (no commitment): X argues, Y claims, scholars believe

A question asking what the author "would agree with" must be answered from the first two categories - never from the speculative or reported ones.

Considering Alternative Explanations

ETS rewards test-takers who can generate alternative explanations for the data in a passage. When you see a causal claim, pause and ask:

• Is there another cause that could produce the same effect?
• Is the correlation in the opposite direction?
• Is there a common cause driving both observed variables?
• Is the sample too small or biased to support the claim?

If a question asks which fact would most weaken the argument, the right answer is usually the one that introduces the strongest alternative explanation. If it asks which fact would most strengthen, the right answer is usually the one that rules out the most plausible alternative explanation.

Worked Example

Passage excerpt: "Cities that installed protected bike lanes saw a 20% drop in cyclist fatalities over five years. The lanes, therefore, save lives."

Before answering any question, extract:

• Claim: Protected bike lanes reduce cyclist fatalities.
• Assumption (causal): The drop in fatalities was caused by the lanes, not by something else - slower traffic, fewer cyclists, better helmets, weather.
• Assumption (representativeness): The cities studied are representative of cities in general.
• Author commitment: Strong - "therefore" signals confidence.
• Weaken candidate: "Cyclist volume in those cities fell by 30% over the same period." This introduces an alternative explanation: fewer cyclists on the road, not safer lanes.
• Strengthen candidate: "Cyclist volume in those cities rose 10% over the same period." This rules out the 'fewer cyclists' alternative.

Common Inference Traps

• The restatement trap. A choice that paraphrases a passage sentence is often the right answer to a detail question but the wrong answer to an inference question; inferences must go one step beyond what is stated.
• The outside-knowledge trap. A choice that is true in the real world but not supported by the passage is always wrong on the GRE.
• The reverse-inference trap. A choice that would explain the passage ("if X were true, the passage would make sense") is not the same as an inference ("if the passage is true, X must be true"). Direction matters.
• The extreme-language trap. A choice that upgrades the passage's hedged language into absolute language is almost always wrong.