Mensa IQ Test Mensa IQ Syllogisms and Logical Arguments 7

Question 1

Premises: Some A are B. Some B are C. Which conclusion is valid?

Accepted Answer

Nothing necessarily follows

Answer

Two particular premises (II) yield no valid syllogistic conclusion by the rules of syllogistic logic.

Question 2

All democracies hold elections. Country X holds elections. Can we conclude Country X is a democracy?

Accepted Answer

No — this affirms the consequent

Answer

Elections are necessary but not sufficient for democracy; concluding X is a democracy from elections alone is affirming the consequent.

Question 3

No mammals lay eggs. Platypuses lay eggs. Therefore:

Accepted Answer

Platypuses are not mammals (given these premises)

Answer

Given these premises formally, modus tollens says platypuses are not mammals — though biologically false, the syllogism is valid.

Question 4

Argument: 'The ancient Greeks believed the Earth was flat, therefore it must have been flat then.' This is:

Accepted Answer

Appeal to tradition (false)

Answer

Using historical belief as proof of truth is an appeal to tradition, which does not establish factual accuracy.

Question 5

All M are P. No S are M. Which conclusion is valid?

Accepted Answer

Nothing can be concluded about S and P

Answer

No valid conclusion: S may or may not be P — they simply aren't M; other routes to P exist.

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