Boston — Sheila Tobias knew something was amiss when she started finding dozens of well-educated women around the country admitting they didn't know what the ''S'' in SALT stood for.
''I realized that these women didn't understand the technology enough to know that strategic arms are nuclear weapons of intercontinental range. Not knowing that, they really didn't know what SALT II was about. I pointed out to them that without knowing that they couldn't really defend SALT II - or attack it, for that matter.''
The problem is that people are baffled by the vast amount of complex information about defense and often avoid it, says Ms. Tobias, a visiting professor of political science at the University of Arizona, Tucson.
Active in antiwar politics in the 60s, she now wants to blast holes in the notion that defense is something only military experts can - or should - understand. To shed some light on the subject for readers who don't know an MX from a Minuteman from a MIRV, she recently wrote (with Peter Goudinoff, Shelah Leader, and Stefan Leader) ''What Kind of Guns Are They Buying for Your Butter: A Beginner's Guide to Defense, Weaponry, and Military Spending'' (William Morrow , New York, $15.95).
Unfortunately, Ms. Tobias says, let-the-experts-handle-it thinking is all too common among women. She believes the price they pay for not learning about defense is giving up their rights as citizens in influencing vital congressional and local political decisions. ''Lack of information is debilitating,'' she says. ''The person who has the information for better or for worse dominates your thinking.''
Yet citizens armed with some knowledge of weapons can have an impact on military decisions, Ms. Tobias says. She points out that former Utah state Sen. Frances Farley ''helped turn around the MX basing scheme in Utah with a $6.95 calculator.''
It all happened in 1979 when the Air Force was briefing the Utah Legislature about placing the controversial MX missile in shelters there. Senator Farley, after some simple calculations, discovered that the amount of land the Air Force would require represented an area the size of Pennsylvania. As Ms. Tobias explains, ''She said to her colleagues, 'Do you realize how much land this is going to take up?' She later organized a successful anti-MX campaign in Utah.''
Tackling women's aversion to learning about vital subjects is a familiar theme for Ms. Tobias. In the 1970s as an administrator at Wesleyan University, she started noticing women students who did well in humanities classes but skirted math and science. Researching this led her to write ''Overcoming Math Anxiety'' in 1974 and to form an institute of the same name in Washington, D.C., that developed counseling and math studies programs for schools.
''What Kind of Guns Are They Buying for Your Butter?'' forges a clear path through the thicket of defense information, guiding the reader through the history of weapons and their uses, costs, and effects. Ms. Tobias is not entirely unbiased. Although she says, ''The issue isn't pro-war or antiwar, it's which military system will guarantee our safety and security,'' her book does offer more to those who would halt or scale down the weapons production rather than forging ahead. She asks pointed questions, such as: ''Will nervous, underskilled soldiers be able to manage and maintain state-of-art technology in the midst of battle? Are there easier, cheaper, entirely different ways of achieving comparable military preparedness? And what kinds of battles (and where) are we talking about?''
Ms. Tobias is serious about the book's being a ''beginner's guide.'' She sought out another beginner, Mrs. Leader, to help her ask questions, and two experts, Mr. Leader and Mr. Goudinoff, to answer them. Because the book was written by people who were learning as they went, she says, ''There's never a time when the beginner feels lost or left behind or dumb.''
What can a newly informed reader do? Ms. Tobias says that too often women have a general ''for peace, against war'' philosophy - but know little about specifics. She cites a comment by US Rep. Patricia Schroeder (D) Colorado that constituents often protest the slashing of favored social programs but don't suggest where the money to pay for them should come from.
''If the people who want a $48 million-a-year child-abuse program, for example, were to come in with a plan and say, 'We can do with one less fighter plane with a $50 million price tag in order to have this,' Representative Schroeder feels that politically that would be a very effective ploy,'' Ms. Tobias says.
She recommends focusing on one weapon system at a time. She says that despite the furor over weapons, her contacts in Congress report very little lobbying on defense issues, except by military contractors.
She adds: ''I think Congress is very vulnerable to citizen input. Every weapon has a price tag that has to go through congressional approval. Some weapon systems are voted on as many as 18 times by the Congress over a 4- to 5 -year period'' at various phases. Each of these phases provides opportunities for lobbying, she says. She recommends that people scrutinize weapon systems being considered: ''After all they're your weapons; they're 50 cents out of your tax dollar.''
Asking difficult questions is not foreign to her. After receiving her BA from Radcliffe in history and literature, Ms. Tobias trekked off to Europe to work as a journalist. She was involved in activist politics in the 60s, then with the women's movement in the '70s. She was a cofounding member of the National Organization for Women and started one of the first women's studies programs as an administrator at Cornell University.
Ms. Tobias doesn't claim to be an expert on defense. But helping to pass on what she's learned to other women to close the ''knowledge gap'' is still important to her.
''I can't pretend to design a weapons system,'' she says, ''but I can critique it in the interest of its mission and its consequences for my country.''