FIRST came years of being a foot messenger in New York City and working in data entry. Then, frustrated with his life, and feeling the responsibility of providing for a child, Michael D. Hattem entered the Borough of Manhattan Community College — the only college that would admit him, he says, as a high school dropout with a G.E.D. He succeeded at community college, and, in 2011, graduated from City College.

Today, Mr. Hattem, 38, is a graduate student at Yale working on a dissertation in American history that “explores the role of competing historical memories of 17th-century Britain in shaping late colonial political culture.”

He told his exceptional story to help explain why he came to the defense of the American Historical Association last week when it issued a statement calling on universities to allow newly minted Ph.D’s to “embargo” their dissertations for up to six years — that is, keep them from being circulated online....