In response to congressional demands for a look at alternatives to current military policies, Defense Secretary Caspar W. Weinberger has directed the Joint Chiefs of Staffs to organize a free-swinging group of second-guessers.

"The staff should consist of bright, articulate thinkers not identified with any particular schools of thoughts, ideologies or hobby-horses," Weinberger said in a memo to Gen. David C. Jones, chairman of the Joint Chiefs of Staff.

"They should have the reputation of challenging existing concepts, of being known as people who look at things differently and of being able to think creatively with maximum analytical rigor about broad policy and strategy issues," the memo continued.

A recently formed congressional group called the Reform Caucus suggested in a meeting with Weinberger June 16 that he avail himself of more independent advice before committing himself to multibillion-dollar purchases of super-weapons pressed upon him by military leaders.

Whether the caucus, founded by Sen. Gary Hart (D-Colo.) and Rep. G. William Whitehurst (R-Va.) and made up largely of pro-defense senators and representatives, will regard an outside group named by the Joint Chiefs as detached enough from existing Pentagon constituencies remains to be seen.

Weinberger instructed Jones to attach the new analysis group to the National War College of the National Defense University, both at Fort McNair in Southwest Washington. Air Force Gen. John Pustay, president of the university, had planned to establish a Strategic Concepts Development Center there.

This center, Weinberger wrote Jones, "if of sufficient quality and capability," would provide the desired second opinions on strategic questions. The defense secretary suggested five analysts and a staff of two, plus employment of outside consultants and "limited use" of students at the National Defense University. The analysts would serve two years at the pleasure of the defense secretary.

Weinberger promised that he and Deputy Defense Secretary Frank C. Carlucci would meet with the analysts once a month "in free-wheeling, informal give-and-take sessions in an environment of maximum confidentiality."