Full Idea
We can say that a phenomenon is 'weakly emergent' when it is unexpected, and 'strongly emergent' when it is not deducible even in principle.
Gist of Idea
Weak emergence is just unexpected, and strong emergence is beyond all deduction
Source
S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 4.3)
Book Reference
Anjum,R.J./Mumford,S.: 'Getting Causes from Powers' [OUP 2011], p.92
A Reaction
[compression of Chalmers 2006:244] I don't find emergence very interesting, since weak emergence surrounds us all day long, and is the glory of the world, and strong emergence is (I believe) nonsense.