What is conversion in logic?
Hint: The converse of 'No cats are dogs' is 'No dogs are cats'
Which propositions can be validly converted by simple conversion?
Hint: 'No S are P' converts to 'No P are S'; 'Some S are P' converts to 'Some P are S'
What is the converse of 'No cats are dogs' (E)?
What is obversion?
Hint: 'All S are P' becomes 'No S are non-P'
What is the obverse of 'All dogs are mammals' (A)?
Can all four categorical propositions (A, E, I, O) be validly obverted?
What is contraposition?
Hint: 'All S are P' becomes 'All non-P are non-S'
Which propositions can be validly contraposed?
What is the converse of 'Some birds are pets' (I)?
Why can't A-propositions be simply converted?
Hint: 'All dogs are animals' does NOT mean 'All animals are dogs'