  In this paper I discuss both syntax and semantics of subjective probability.
The semantics determines ways of testing probability statements. Among
important varieties of subjective probabilities are intersubjective
probabilities and impersonal probabilities, and I will argue that well-tested
impersonal probabilities acquire features of objective probabilities.
Jeffreys's law, my next topic, states that two successful probability
forecasters must issue forecasts that are close to each other, thus supporting
the idea of objective probabilities. Finally, I will discuss connections
between subjective and frequentist probability.
