There have been arguments, including in articles here in PA Times Online, that we should now be aiming for less urban density to thwart the spread of deadly viruses like COVID-19. This, of course, assumes that pandemics will now be an annual occurrence and that we should all get used to social (physical) distancing and conducting all of our business on Zoom. If that logic sounds suspect (and depressing), then you should know it is both short-term and reactionary. Absent in this thinking is an understanding of the complex dynamics in our societies. In the case of greater urban density, the benefits clearly outweigh the costs.