The description "soft" science fiction may describe works based on social sciences such as psychology , economics , political science , sociology , and anthropology . Noteworthy writers in this category include Ursula K. Le Guin and Philip K. Dick .   The term can describe stories focused primarily on character and emotion; SFWA Grand Master Ray Bradbury was an acknowledged master of this art.  The Eastern Bloc produced a large quantity of social science fiction, including works by Polish authors Stanislaw Lem and Janusz Zajdel , as well as Soviet authors such as the Strugatsky brothers , Kir Bulychov , Yevgeny Zamyatin and Ivan Yefremov .  Some writers blur the boundary between hard and soft science fiction.
The only book Wolfe has included that I would have omitted is Leiber’s “ The Big Time ” (1958). Leiber was a major writer for more than five decades, and his attentiveness to the rhythms of language marked him out among his contemporaries. But this tale of a “Change War” fought by time travelers has always struck me as congested and slightly contrived: The plot depends on that old cliche, a bomb set to detonate but with a delay just long enough to defuse it. Leiber’s “ The Wanderer ” (1964) would be much more representative a selection if the LoA produces volumes covering later periods. The same could be said of any of a dozen Leiber short stories.