# Re: Paper+Exercises+Naming Issue

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Le 04-janv.-06, à 19:30, Brent Meeker a écrit :```
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```Bruno Marchal wrote:
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```Hi John,
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I think you may have problems because you are not used neither trained in axiomatic thinking. The idea consists in NOT defining the objects we want to talk about, and keeping just some needed properties from which we prove other theorem. Let me give an example with the idea of knowledge. Many philosophers agree that knowledge should verify the following law, and I take it as the best definition of knowledge we can have:
```1) If I know some proposition then that proposition is true
2) If I know some proposition then I know that I know that proposition
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3) If I know that some proposition a entails some proposition b, then if I know a, I will know b.
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But that doesn't capture meaning of "know".
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But nobody knows or agree on the *meaning* of "know", that's was my point. If *you* think it leaves something out, for a mathematician it means that you agree with the definition!
```And then you propose a stronger theory by adding 4:

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It leaves out 4) If I know some proposition then I have experience causally connected to the fact that makes it true. See c.f. Gettier's paradox.
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Now, that "4" *is* problematical because it refers to a undefined notion of causality, which itself can only be defined axiomatically.
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Bruno
http://iridia.ulb.ac.be/~marchal/

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