Second order probability
Luciano Floridi poses the problem of second-order probabilities:
(…) we actually lack a theory of second order probability, let alone a philosophical justification for it.
By second order, he means “probabilities about probabilisties”.
I beg to differ with Luciano. What about this reference?
Gaifman, H. 1986. A theory of higher order probabilities. In Proceedings of the 1986 Conference on theoretical Aspects of Reasoning About Knowledge
Montreal, Canada 
Follow on
A brief description of several similar approaches is also in:
P. Wang. Confidence as higher-order uncertainty. In Proceedings of the Second International Symposium on Imprecise Probabilities and Their Applications, pages 352–361, 2001.
Comment by MartinZ — 10/7/2006 @ 8:29