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A priori & a posteriori

There are two kinds of knowledge: a priori and a posteriori.

A priori knowledge consists of propositions that are knowable independently of experience of the world.

e.g. An octagon has eight sides.

I can know this by simply thinking about the concepts in question.  If I understand what an octagon is, then I know that is has eight sides.

A posteriori knowledge consists of propositions that are known on the basis of empirical experience of the world.

e.g. Smoking is correlated with lung cancer.

To know this I need to make an empirical investigation.

Let's try a practice exercise...

Sort the white boxes into categories according to whether the propositions they contain are a priori or a posteriori.

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After you've finished this exercise click on this thumbnail to see the model answer:

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This material has been developed independently of the International Baccalaureate, which in no way endorses it.

© Critical Thinking Skills BV 2013.  Rationale Exercises version 0.1,