Chapman was a staff writer and associate editor of
The New Republic magazine from 1978 to 1981. He joined the editorial board of the
Chicago Tribune in 1981 and began writing a twice-a-week opinion column on national and international affairs in 1982. His column was syndicated by
Creators Syndicate. He took a buyout from the Tribune in 2021, and currently writes a monthly column for them. Media critic
Jack Shafer has described him as “a polymath, a creative policy wonk, a tap-dancing writer, a true son of liberty, (and) a failed Christian,” noting his “pro-gun, antigovernment, pro-peace, anti-drug-war, pro-market views.” Chapman has described his political views as “moderate
libertarian.” ==Personal life==