If the city puts up a donated 10 Commandments monument, must it put up every other donated monument lest it violate Free Speech?

SCOTUSblog previews tomorrow's oral argument in Pleasant Grove City, et al., v. Summum.

Will the Justices’ vision be fogged by a cloud of potential horribles? The Solicitor General’s brief well illustrates this argument: “Under the decision below, a city’s display of a privately donated monument to Abraham Lincoln could entitle an individual to insist that the city permit the erection of a monument to Jefferson Davis, or a group could insist that the presence of the memorial in [Pleasant Grove’s] Pioneer Park commemorating the September 11 attacks entitles it to erect a memorial to the terrorists who carried them out.”