There is a tendency to think of philosophy of the Middle Ages as being "the Dark Ages". To think of human progress as only progress upwards is however a mistake. There is also progress downwards. There are forces of Darkness. And often these forces are embodied in people.
So the question is how to make sure that you are on the side of good? This is not totally independent of the question of what is the world all about. [Even though Hume held that "ought" and "is" are logically distinct; but they are still connected. That is, they are not identical, but still they are related] The fact of Communism causing the death of almost 100 million people in the USSR and China is not irrelevant to the question if Communism is good.]
So the question is: how to merit to common sense? That is a kind of sense of how to distinguish between good and evil. This is not a question of whether to choose any particular certain belief system or science. It rather seems like a kind of sense that can tell you how to choose.
The philosopher of common sense, Thomas Reid, might help for this. However philosophy does not seem to help anyone come to common sense. Though they might have it before they get involved in philosophy, but after learning philosophy, they lose it. But the same applies to almost any religious belief system.
