NTS NAT-IA Logical Reasoning Syllabus

What is a 'straw man' fallacy?

Misrepresenting or oversimplifying an opponent's argument to make it easier to attack and refute.

What is a valid inference?

A conclusion that must be true given the information provided; it follows necessarily and adds nothing beyond what the statements support.

What is the golden rule for 'Drawing Valid Inferences' questions?

Choose only what must be true based strictly on the given information; avoid answers that require outside assumptions or go beyond the text.

Why are answer choices with extreme words (all, never, only, must) risky in inference questions?

Because strong/absolute claims are harder to fully support from the passage, so they are often unsupported and incorrect compared with moderate ('some', 'may') statements.

What is logical deduction?

The process of deriving a conclusion that necessarily follows from one or more given statements (premises) using valid logical rules.

What is a syllogism?

A deductive argument with two premises (a major and a minor premise) and a conclusion, typically relating three terms via categorical statements.

State the rule of the middle term in a syllogism.

The middle term must be distributed at least once; if it is not distributed in either premise, the syllogism is invalid (undistributed middle fallacy).

Syllogism rule: what can you conclude from two negative premises?

No valid conclusion can be drawn from two negative premises.

Syllogism rule: what can you conclude from two particular premises?

No valid conclusion can be drawn from two particular (some) premises; at least one premise must be universal.

Syllogism rule: if one premise is negative, what must the conclusion be?

If either premise is negative, the conclusion must also be negative.

Syllogism rule: if one premise is particular, what must the conclusion be?

If either premise is particular ('some'), the conclusion must also be particular.

In 'Course of Action' questions, what is a 'course of action'?

A step, decision, or administrative action proposed to solve a problem or improve a situation described in the statement.

What two criteria must a suggested course of action meet to be considered 'follows'?

(1) It must actually address/solve the problem, and (2) it must be practical, reasonable, and not an extreme or one-sided over-reaction.

In course of action questions, why are extreme actions (ban everything, punish all) usually rejected?

Because a valid course of action should be balanced and feasible; extreme or impractical measures are not considered proper solutions.

What is a categorical statement (categorical proposition)?

A statement that affirms or denies that all, some, or none of one category (subject) is included in another category (predicate).

List the four standard types (A, E, I, O) of categorical statements.

A = Universal affirmative (All S are P); E = Universal negative (No S are P); I = Particular affirmative (Some S are P); O = Particular negative (Some S are not P).

Which terms are distributed in an A-type statement (All S are P)?

Only the subject (S) is distributed; the predicate (P) is undistributed.

Which terms are distributed in an E-type statement (No S are P)?

Both the subject and the predicate are distributed.

Which terms are distributed in an I-type statement (Some S are P)?

Neither the subject nor the predicate is distributed.

Which terms are distributed in an O-type statement (Some S are not P)?

Only the predicate (P) is distributed; the subject (S) is undistributed.

What is the Venn diagram method for syllogisms?

A technique using overlapping circles for the three terms; you mark the premises (shading for 'none', X for 'some') and check whether the conclusion is forced by the diagram.

On a Venn diagram, how do you represent a universal statement like 'No S are P' or 'All S are P'?

By shading out the region that must be empty (e.g., shade the S-and-not-P region for 'All S are P', and shade the S-and-P overlap for 'No S are P').

On a Venn diagram, how do you represent a particular statement like 'Some S are P'?

By placing an X in the overlapping region of S and P to show at least one member exists there.

When using Venn diagrams, in what order should universal and particular premises be entered?

Always diagram universal (shading) premises first, then place the X for particular premises, so the X can be positioned unambiguously.

How do you determine validity using a completed Venn diagram?

The syllogism is valid only if the diagram drawn from the premises already shows (forces) exactly what the conclusion claims, with no extra assumption needed.

In 'Statement and Conclusions' questions, when does a conclusion 'follow'?

A conclusion follows only if it can be logically and definitely derived from the given statement(s) alone, without external information.

What is the rule for 'Either-Or' (complementary pair) conclusions?

When two conclusions individually don't follow but together cover all possibilities and form a complementary pair, the answer is 'either conclusion I or II follows'.

In 'Statement and Assumptions' questions, what defines an implicit assumption?

An implicit assumption is something taken for granted by the speaker—an unstated idea that must hold for the statement to be made or to make sense.

In statement-and-assumptions questions, why is a restatement of the given fact NOT an assumption?

An assumption must be unstated and taken for granted; if something is already stated or directly obvious in the statement, it is not an implicit assumption.

Compare a valid conclusion and an invalid conclusion.

A valid conclusion necessarily follows from the premises by logical rules; an invalid conclusion does not necessarily follow, even if the premises are true (the logical link is broken).

What is the key difference between strengthening and weakening an argument?

Strengthening adds support that makes the conclusion more likely to follow (often by confirming the assumption), while weakening undermines the premise-conclusion link (often by attacking the assumption or giving an alternative).