I agree that science is the best way of understanding the natural world, and therefore that we have reason to believe what the best science tells us about the objects in that world and the relations between them. But this does not mean that the natural world is the only thing we can have true beliefs about. The status of material objects as things that are "real" is a matter of their having physical properties, such as weight, solidity, and spatio-temporal location. In order to be real, such things need not have, in addition to these properties, some further kind of metaphysical existence.