Section 3.4: Evaluating Inferences and Strength of Arguments

Evaluating Inferences and Strength of Arguments

In the Logical Reasoning domain of the Foreign Service Officer Test (FSOT), you will be called upon to assess the validity of inferences and evaluate the relative strength of arguments. These skills mirror the daily responsibilities of a diplomat: reading cables to extract only what is verified, and determining how new events or intelligence strengthen or weaken policy proposals.

1. Drawing Valid Inferences: The Must-Follow Standard

On the FSOT, a valid inference is a statement that is logically compelled by the provided text. It is not an educated guess, a reasonable prediction, or a projection based on your knowledge of foreign affairs. If the stimulus is true, the correct inference must also be true.

This strict standard differs from everyday usage, where "infer" often means "speculate." To avoid traps, apply the Must-Follow Test: ask yourself if there is any possible scenario where the stimulus is true but the inference is false. If such a scenario exists, the inference is invalid.

Hedges and Scope: The Key to Elimination

Most wrong answers on inference questions fail because they expand the scope of the stimulus. Pay close attention to quantifier and probability words:

• Quantity: "All," "most," "some," "none," "only."
• Probability: "Will," "should," "may," "might," "unlikely."

If the stimulus states that "some economic attaches reported high stress," a choice claiming that "attaches in the economic section are experiencing high stress" is an overreach—it implies a general condition when the text only supports a subset.

Worked Example: The Tariff Stimulus

• Stimulus: Of the seven nations in the trade bloc, only those that reduced tariffs on raw agricultural products saw their manufacturing sectors grow last year.
• Analysis: This statement establishes a necessary condition: if a bloc nation saw manufacturing growth (G), it must have reduced agricultural tariffs (R). Mathematically: $G \rightarrow R$.
• Valid Inference: If a trade bloc nation did not reduce tariffs on raw agricultural products last year, its manufacturing sector did not grow. (This is the contrapositive: $\neg R \rightarrow \neg G$, which must be true).
• Invalid Inference (Trap): Reducing tariffs on raw agricultural products guarantees growth in a nation's manufacturing sector. (This is the converse fallacy: $R \rightarrow G$. The text does not say all nations that reduced tariffs saw growth, only that those that saw growth had reduced tariffs).

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2. Evaluating Argument Strength: Hitting the Pivot

An argument's strength is the degree to which its premises support its conclusion. Evaluating strength on the FSOT usually involves identifying what would strengthen or weaken a claim. The key to these questions is identifying the argument's pivot—the gap between the premises and the conclusion.

• To strengthen an argument, you must select a fact that supports the underlying assumption, blocks alternative explanations, or confirms the causal mechanism.
• To weaken an argument, you must select a fact that undermines the assumption, introduces alternative causes, or demonstrates that the mechanism is flawed.

Causal Arguments

Many FSOT stimuli assert a causal relationship: "A happened, then B happened, so A caused B."

• To Strengthen: Show that in a similar environment where A was absent, B did not happen (a control group); or show that when A is increased, B increases proportionally (dose-response).
• To Weaken: Provide an alternative cause (Event C caused B); or show that B happened before A occurred (reverse chronology).

Recommendation Arguments

Some arguments conclude with a policy recommendation: "We should implement policy X."

• To Strengthen: Provide evidence that the benefits of X outweigh its costs, or that X successfully solved an identical problem elsewhere.
• To Weaken: Show that X has failed in similar circumstances, or that X will create severe unintended side effects that outweigh its benefits.

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3. Parallel Reasoning: Stripping the Subject Matter

Parallel reasoning questions ask you to identify the answer choice that contains the same logical structure as the stimulus. The content of the choices is completely irrelevant; they may discuss farming, city planning, or chemical reactions while the stimulus discusses diplomacy.

To master these questions:

1. Map the stimulus into abstract variables (e.g., A, B, C).
2. Identify the logical operators (if-then, and, or, not).
3. Write out the abstract logical flow.
4. Match this flow to the choices, ignoring the subject matter.

Worked Example: The Treaty Veto

• Stimulus: If the President signs the treaty, the senate will veto it. The senate did not veto it. Therefore, the President did not sign the treaty.
• Logical Map: If P, then V. Not V. Therefore, not P. (Modus Tollens: $P \rightarrow V$, $\neg V \rightarrow \neg P$).
• Answer Choice Match: "If the crop receives enough water, it will yield fruit. The crop did not yield fruit. Therefore, the crop did not receive enough water." (If W, then F. Not F. Therefore, not W. This is a perfect logical match).

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4. FSOT Argument Traps