This paper would like to argue that the two questions in its title are really one and the same and, moreover, that a certain way of answering them can help us understand the question: What happens when the avant-garde of yesterday becomes academic? Indeed, what remains of the 19th century in the art of the 20th is art in general, by which is meant a situation in which it has become technically possible and institutionally legitimate to make art using anything and everything. Often seen as a consequence of Marcel Duchamp’s invention of the readymade, this situation is in fact its prerequisite. My paper offers a historical and theoretical interpretation of art in general, centred on the notion of convention and destined to displace other, ideological, definitions of the avant-garde.V članku trdim, da sta vprašanji, ki sta zastavljeni v njegovem naslovu, dejansko eno in isto vprašanje. Poleg tega želim zagovarjati stališče, da nam določen način odgovora nanju lahko pomaga razumeti vprašanje o tem, kaj se zgodi z včerajšnjo avantgardo, ko ta postane akademska. Prav res, kar ostane od 19. stoletja v umetnosti 20., je umetnost na splošno, s čemer je mišljena situacija, v kateri je postalo tehnično možno in institucionalno legitimno izdelovati umetnost z uporabo česarkoli in vsega. Čeprav se pogosto meni, da gre tu za posledico Duchampovega izuma ready-madea, je ta situacija v resnici njen predpogoj. Moj članek nudi zgodovinsko in teoretsko interpretacijo umetnosti na splošno, ki je osredotočena na pojem konvencije ter namenjena temu, da nadomesti druge, tj. ideološke definicije avantgarde
