According to the theory of consequentialism, people ought to aim to take the actions that will produce the best possible outcomes. It then follows that we ought to try to identify these actions as well as we can, by gathering and assimilating evidence.
While formal epistemology, and in particular Bayes’ rule, provide us with mathematical instructions for updating our credences in the face of new evidence, they do not tell us how to go about gathering this evidence or how to deal with complications that may be difficult to represent in a mathematically precise way.
Some topics relevant to the practical assessment and assimilation of evidence include:
Randomized controlled trials: A particularly useful, though far from perfect, method for acquiring evidence.
Tested interventions vs. speculative interventions: we often face a tradeoff between interventions which may be higher impact, and those for which we have more solid evidence.
The use of models: models are simplified versions of the world that can provide a useful perspective on how the world is.
Cognitive biases: biases can affect our assessment of the evidence, so it is important to be conscious of them and attempt to avoid them.