What was the problem with William of Ockham and nominalism?

The basic problem with Ockham and his group was nominalism as a metaphysical philosophy, which can be very destructive. Nominal means name, as if you put a name on something and it becomes that just because of the name, and this got in the way of God. Take the old question, can God make a square circle? The nominalists would tend to say yes, God can do anything, whatever you can name; but the other side says no, because first you have to determine whether the thing contemplated is truthful, and if it is not, God cannot do it, since God cannot lie, and a square circle is not truthful because there is no such thing. So with that kind of metaphysics behind your epistemology, everything is up in the air and you have God supposedly doing things that are contradictions. Ockham is also famous for Ockham's razor, the axiom that the simplest answer is probably the best. In practice that is often close to the truth, because nature tends to take the simplest route, but it is not always true; sometimes nature has to take a complicated route because of other contingencies, as we see in how DNA and the cell work, so the simplest solution is not necessarily the correct one.