FOR nearly two decades, a group of dissident defense intellectuals has been thriving in the penumbra of major national defense debates. Not really an underground, the group includes both civilians and military officers-and some who have been both-who are or have been associated with the Defense Department or with influential U.S. senators and congressmen. Their shared distinction is their attitude toward national security issues, particularly the design and procurement of mafor weapon systems. They are iconoclasts, determined critics of mainstream thinking in the military services and in the defense research and engineering community. They are relentlessly empirical-indeed, anti-theoretical—collecting data from the real world of combat and from realistic military exercises, poring over it, searching for serviceable truths in the actual experiences of fighter pilots, infantry soldiers, and submarine skippers. They are smart and inventive, faithfully translating the truth they discover into ideas for new or improved rifles, aircraft, ships, and missiles which, they insist, unlike the weapons conceived by the mainstream research and engineering community, will enable American troops to defeat enemy forces in combat. Articulated, the group’s credo would be, “when in doubt, build it simple, rugged, reliable, and maintainable,” but in general they scrupulously avoid becoming doctrinaire. They are often right, or, more accurately, they are often persuasive; because they don’t win many debates over how weapons should be designed and procured, evidence to justify their claims is sparse.