The main topic of the book is how to argue for formal epistemic norms of credence. The author advocates formal justificational pluralism, suggesting that it is reasonable to use various formal tools, e.g. different "scoring rules," in arguments for synchronic and diachronic norms. Leszek Wroński first examines various occasions on which modern formal epistemology fails to live up to its "formal" label. Among the topics considered next are: the Dutch Book Theorem and Arguments (which fails according to the author), a novel version of the Principal Principle, and a constructive approach to higher order probabilities. The author argues then that the best method for dealing with various belief update problems is that of minimizing inverse relative entropy, and defends the claim that for evaluating an agent's credal state at a single moment the Brier Score seems to be the way to go.