On How to Do Things with Words (lectures from 1955). What's the relationship between language and the world? Austin says it's not all about descriptive true-or-false statements, but also includes "performatives" like "I promise…" and "I do" (spoken in a wedding) that are actions unto themselves. They can't be true or false, but they can be "unhappy" if social conventions aren't fulfilled (e.g., you try to marry a pig). Austin thinks performatives will change your whole view of language and of linguistically expressed philosophical problems!