  For comments, I would like to thank Alan Bale, Francis Corblin, Carmen Dobrovie-Sorin, Brendan Gillon, Giorgio Magri, Barry Schein, Mark Steen, Martin Stokhof, Lucia Tovena, and an anonymous reviewer for Stanford Encyclopedia of Philosophy. Thanks also to audiences in Istanbul, Montreal, Paris, and Storrs for their feedback. This work was supported by the  grants ANR-10-LABX-0087 IEC and ANR-10-IDEX-0001-02 PSL*.