The bottom-up method is much less ambitious than the top-down kind, but it has two advantages: it makes fewer assumptions about theory, and it’s tightly tethered to data. This doesn’t mean we need to give up on the old unification paradigm, it just suggests that we shouldn’t be so arrogant as to think we can unify physics right now, in a single step. It means incrementalism is to be preferred to absolutism – and that we should use empirical data to check and steer us at each instance, rather than making grand claims that come crashing down when they’re finally confronted with experiment.