Regarding Shermer on science being uncertain: I listen to a lot of skeptics, and I think he's merely saying that science cannot be literally 100% absolute in its certainty. Sure, a theory can explain all the existing evidence (known cases) and make accurate predictions its scope about unexamined cases. But empirical test of it can only ever approach 100% certainty and can never really achieve it.

Thats just my take on it.