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thinking skillsLogical Reasoningcore

Logical Deduction

Learn to draw specific conclusions from general statements using deductive reasoning.

Key Ideas

  • Deduction moves from general rules to specific conclusions.
  • If the premises are true and the logic is valid, the conclusion MUST be true.
  • Watch out for words like 'all', 'some', 'none', 'always', and 'never'.
  • Use Venn diagrams to visualize relationships between groups.

Worked Examples

Example 1

All birds lay eggs. Penguins are birds. Therefore...

Explanation

Premise 1: All birds lay eggs (General Rule).

Premise 2: Penguins are birds (Specific Case).

Conclusion: Penguins must lay eggs.

This is a valid deduction.

Ready to Practice?

Test your understanding of Logical Deduction with targeted questions from our bank.

Common Mistakes
  • ×Assuming 'Some A are B' means 'Some A are not B' (it might not).
  • ×Confusing 'All A are B' with 'All B are A'.
Exam Tip

"If you can draw a diagram where the conclusion is false while the premises remain true, then the argument is invalid."