Probability theory is nothing but common sense reduced to calculation. Laplace, 1819
2 计算法则
We have now formulated our problem, and it is a matter of straightforward mathematics to work out the consequences of our desiderata, which may be stated broadly as follows:
(I) Representation of degrees of plausibility by real numbers; (II) Qualitative correspondence with common sense; (III) Consistency.
The present chapter is devoted entirely to deduction of the quantitative rules for inference which follow from these desiderata. The resulting rules have a long, complicated, and astonishing history, full of lessons for scientific methodology in general (see the Comments sections at the end of several chapters).
概率论只不过是将常识简化为计算罢了,没有其他了。 --拉普拉斯，1819年
现在我们已经明确的阐述了我们的问题，下面就是如何用数学方式从基础原理得出结论.基础原理大致陈述如下：
（I）用实数来表示似真度; （II）定性的对应于常识; （III）一致性。
本章致力于从以上基础原理通过演绎得出推理的量化规则。 这些规则有一个漫长复杂且令人惊讶的历史，充满了我们学到的广义的科学方法论的各种教训（见各章末尾的评论部分）。