 The interaction claim itself should be understood as follows: some events that have a mental description or instantiate a mental property cause and are caused by events that have a physical description or instantiate a physical property. Formulating the interaction principle in this way both clears the way for an extensional reading of the causal relation (events are causally related no matter how they are described), and also leaves open the possibility, which Davidson will subsequently argue for, that mental events in particular must have some non-mental description/instantiate some non-mental property. At this stage that possibility is left as an open question, but it is important to notice that for it to be an open question we need to at least allow for a distinction between events and the ways in which they are picked out in language.