Michael Behe is a Professor of Biochemistry at Lehigh University in Pennsylvania. A Senior Fellow at the Center for Science and Culture at the Discovery Institute, he is one of the main proponents of Intelligent Design (ID) theory.
The general thrust of Behe's argument is that there are a number of biochemical "machines" which cannot be explained through natural selection. Behe defines this phenomenon as irreducible complexity, referring to a biochemical system which — if any part is removed — stops functioning. He promotes this idea in his book Darwin's Black Box.