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Nydus Open Learning

Logic and philosophy

Logic and philosophy · Topics commonly taught around grade 8

Reasoning about evidence

Unit

What a sample covers and who it could never have reached; how a sample was chosen, and the difference between a sound method and a skewed one; what a count out of a sample permits, and what the words some, most and all allow; the two-by-two table behind every claim that one thing goes with another; base rates, and why a good test for a rare condition still gives far more false alarms than real ones; what an accuracy figure leaves out; conditional claims, their converse and their contrapositive; necessary and sufficient conditions and the two words only if; the two valid moves from an if-then and the two invalid ones they are confused with; and the difference between an argument being valid and its conclusion being true.

Ages 13–14 14 lessons about 9.5 hours in all

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The lessons

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  1. 1 The group measured and the group claimed
  2. 2 How the sample was chosen
  3. 3 What a count out of a sample permits
  4. 4 What some, most and all permit
  5. 5 The table with four boxes in it
  6. 6 Why a good test for a rare thing misleads
  7. 7 What an accuracy figure leaves out
  8. 8 What an if-then claim says
  9. 9 The converse is a different claim
  10. 10 The one swap you are allowed to make
  11. 11 Necessary and sufficient conditions
  12. 12 Only if, and if and only if
  13. 13 Four moves from an if-then
  14. 14 Valid is not the same as true