In this paper, we survey several many-valued propositional logics in which
the truth-functions (in the real unit interval [0,1]) of their connectives
are definable only from the natural ordering of the scale, without using an
y richer algebraic structure. In particular we describe a complete notion o
f proof for weighted formulas of the implication-free fragment of Godel log
ic with involution. The usefulness of this logical framework for the formal
ization of ordinal preference modelling is also shown. (C) 2001 Elsevier Sc
ience B.V. All rights reserved.