Duchamp’s readymades are acts of ontological transubstantiation, they nominate non-artistic objects as artworks. This is aesthetic blasphemy.
Nominating a non-art object as an artwork requires that the object not be an art object. But imagine that you have a time machine. Now you can go back in time to ancient Rome or Greece with any non-art object the artist seeks to nominate as an artwork and have it accepted as a work of art. Not declared, displayed and accepted.
Assuming you avoid paradoxes, the object will not have been nominated as an art object and will never have been a non-art object. Is this just nomination at an extra level of indirection, or does it undo the readymade?
(From a conversation with Evie.)