Many epistemologists think we can derive important theoretical insights by investigating the English word ‘know’ or the concept it expresses. However, native English speakers make up less than 6 % of the world’s population, and some empirical evidence suggests that the concept of knowledge is culturally relative. So why should we think that facts about the word ‘know’ or the concept it expresses have important ramifications for epistemology? This paper argues that the concept of knowledge is universal: it is expressed by some word in every natural language. I also explore the implications of this thesis for philosophical methodology.