Today we saw how Hume adjusts to a world in which he can find no necessary connection between cause and effect.
Although we cannot find an idea of necessary connection between causes and effects, Hume thinks we can be aware of a customary connection. This is to say that we recognize that what we receive in perception is a stream of ideas, it is up to us to arrange them as cause to effect. But once we recognize the role played by custom, we talk of what is plausible (it is more plausible that bread will nourish us than poison us, for example).
The orderliness of custom also, Hume thinks, shows us how to understand human freedom. There is such a thing as human nature - people are fundamentally the same everywhere - and our accounts of freedom should be located within that nature. Once we understand that our decisions are the products of our character and history (for what else could produce them?) we can see that there is no real problem of freedom. To be free is not to be a prisoner, drugged, or otherwise coerced. Hume is then a compatibilist, a soft-determinist. He sees no conflict between freedom and determinism (or as he might put it, the regularities we find in the world).
Hume also argues against miracles. We are constantly observing regularity, but no necessary connection. That means that miracles that conflict with natural laws are exceptions to those regularities, and, Hume thinks, contradict our previous experience. No wise person would ever believe reports of a miracle, Hume thinks.