Martin Löf's lectures on type theory are pretty much the clearest explanation of modern mathematical logic that you'll find anywhere. Some of the technical resu

Martin Löf's lectures on type theory are pretty much the clearest explanation of modern mathematical logic that you'll find anywhere. Some of the technical results turned out to be false, or at least needed more work, but the analysis of inductive definitions and equality is and was groundbreaking. Since this is more mathematics than philosophy, the latest truly novel idea is also a few months old instead of a few decades. You really just have to start somewhere and work your way forward. :)