Complex sentence: Believing that socialism afforded an alternative to the prevailing industrialist culture (Young 3), he joined the Kentucky chapter of the American Socialist Party, and in 1932 actively campaigned for Norman Thomas, the standard-bearer of that party.
Split into simpler sentences: Believing that socialism afforded an alternative to the prevailing industrialist culture (Young 3), he joined the Kentucky chapter of the American Socialist Party. In 1932 Weaver actively campaigned for Norman Thomas, the standard-bearer of that party.