Continuity, Variation, and Selection
The style wars between modernism and traditional design usually get stuck on the false choice between continuity and change, as if tradition just means copying the past, and breaking tradition equals modernity. Neither really captures the algorithm we need to follow in order to build better places: evolution. Evolution begins with the past, copying it. Then it goes much further.
First, we copy. Since we're conscious people and not molecules unzipping and zipping DNA strands, of course we choose what we copy, but still we should start with the known. So we start by finding some precedent, but from there we do well to lift liberally.
Next we vary: introduce variations. Since we are conscious, we usually introduce variations as we solve problems. Traditional designers are often accused of being un-creative, but creativity always comes in any time they try to solve problems. One of the most original buildings of the 20th century, in fact if not image, is Grand Central Terminal in Manhattan. Certainly it seems "old fashioned" in its marble and Roman architecture, but it was unprecedented at the time, both from an artistic standpoint and from a planning standpoint. No station or terminal had provided such a large and spacious concourse, and none had such a complex and functional multi-layered circulation system.
The next step is to filter the good from the bad -- an artificial version of natural selection. For better or worse, buildings aren't usually killed off by other buildings, so architectural evolution requires a little help. We have to ask whether solutions are good or bad. That way we can keep the good ones and kill off the bad variations. Grand Central Terminal has progeny because it worked.
This is architectural evolution. Is it modern, is it old-fashioned? Let's keep what works, discard the rest, and see what happens.