The online magazine Slate said Wednesday that it is laying off four staff members, including media critic Jack Shafer and columnist Timothy Noah.

Shafer, who began writing the widely read Press Box column in 2000, was one of Slate’s founders, joining the publication before its official launch in mid-1996. Noah, who writes the Chatterbox column, joined soon after.

Slate is owned by The Washington Post Co., which bought it from Microsoft in 2004 for an undisclosed sum.

The Washington-based publication has about 40 full-time editorial employees.

Shafer said Wednesday that he will continue to contribute to Slate and that he will begin freelance writing. He has two assignments lined up, for The Post and the New York Times — two publications that were often the subject of his insightful and sometimes cutting critiques of the news media’s vanities and foibles.

He was reflective and analytical about losing his job, noting that news organizations have been shedding journalists for years. “The Washington Post has done this. The New York Times has done this,” he said by phone. “It doesn’t necessarily mean a huge, unsolvable crisis. It just means we have to economize. Many publications have to right-size themselves in this current economic environment.”

Noah also will continue to contribute to Slate. He is on leave to complete a book about income inequality, based on a 10-part series he wrote for the magazine last fall. In April, the series, “The Great Divergence,” won the Hillman Prize, which recognizes stories that explore social and economic issues.

Slate also laid off foreign editor June Thomas and associate editor Juliet Lapidos. David Plotz, Slate’s editor, called the layoffs “very painful.”

“We’re losing some wonderful colleagues and great journalists,” he said, noting that “in the environment we’re facing, these cutbacks are important and necessary for us, as painful as they are.”

The news about Shafer came on the same day that American Journalism Review published a lengthy profile of him, in which peers called him one of the nation’s preeminent media critics. The article was accompanied by an online commentary by AJR’s editor, Rem Rieder, who criticized Slate for what he called “a truly befuddling and disappointing decision” in laying off Shafer. Shafer’s wife, Nicole Arthur, is an editor in The Post’s Style section.