Why diachronically emergent properties must also be salient
Résumé
In this paper, I criticize Bedau's definition of ‘diachronically emergent properties' (DEPs), which says that a property is a DEP if it can only be predicted by a simulation (simulation requirement) and is nominally emergent. I argue at length that this definition is not complete because it fails to eliminate trivial cases. I discuss the features that an additional criterion should meet in order to complete the definition and I develop a notion, salience, which together with the simulation requirement can be used to characterize DEPs. In the second part of the paper, I sketch this notion. Basically, a property is salient when one can find an indicator descriptive function (DF) that is such that its fitting description shifts from one elementary mathematical object (EMO) to another when the property appears. Finally, I discuss restrictions that must be brought to what can count as DFs and EMOs if the definition of salience is to work and be non trivial. I conclude that salience (or a refined version of it) can complete the definition of DEPs.