This paper continues Dietrich and List's [2010] work on propositionalattitude

aggregation theory, which is a generalised unication of the

judgment-aggregation and probabilistic opinion-pooling literatures. We

rst propose an algebraic framework for an analysis of (many-valued)

propositional-attitude aggregation problems. Then we shall show

that systematic propositional-attitude aggregators can be viewed as

homomorphisms in the category of C.C. Chang's [1958] MV-algebras.

Since the 2-element Boolean algebra as well as the real unit interval can be

endowed with an MV-algebra structure, we obtain as natural corollaries

two famous theorems: Arrow's theorem for judgment aggregation as well

as McConway's [1981] characterisation of linear opinion pools.