The talent shortage that never materializes was proclaimed again this week on Capitol Hill, this time by Microsoft’s Bill Gates, who warned that American companies “face a severe shortfall of scientists and engineers with expertise to develop the next generation of breakthroughs.”

To bring on those breakthroughs, Gates, and many others, call for allowing the entry of more foreign talent, as well as improving American science and math education to produce more home-grown talent.

The scientist and engineer shortage or shortfall—we’ll get to the difference in a moment — is a familiar specter at Congressional hearings. The reason is, in defiance of facts, it suits the needs of higher education, industry, and the federal research bureaucracy, even if it doesn’t exist. For academe, a dearth of scientists and education clearly means Washington must provide more money for academic science and engineering. For industry, it means immigration barriers must be lowered to bring in more foreign scientists and engineers, who generally work for lower pay, despite presumed safeguards against cheap labor undercutting domestic wages. For the government research agencies, it means bigger budgets are essential.

Strangely, the alleged shortages have not sent wages soaring in science and engineering, nor have they have created a job-seeker’s nirvana in these fields. Any university advertising a tenure track opening will find its e-mail swamped with resumes from well-qualified applicants. The market for engineers varies with time, place, and specialty, but many engineers report difficulty in finding work suitable for their talent and experience.

America has never produced enough scientists and engineers for its needs, and foreigners have long flocked here to fill the gaps, and continue to do so. Foreign scientists and engineers built the atomic bomb, directed the moon landings, and heavily populate Silicon Valley. Warnings that someday they will all return to their native lands are empty alarms. Some return, most stay, while many others strive to come here. “Stay rates,” as they’re known, remain very high.

The dearth of Americans going into science and engineering may be attributable in part to the relative unpopularity and poor quality of science and math studies at the secondary levels. But many students well qualified for studies leading to careers in these fields choose to proceed elsewhere — for sound economic reasons. Five to seven years of postgraduate work are generally required for a science Ph.D. Jobs in the life sciences are especially scarce, with the pharmaceutical industry cutting back on research; and so are grants from NIH, where the average age of first-time grantees is over 40. Job opportunities and careers in engineering are especially vulnerable to the ups and downs of defense and aerospace spending and the vagaries of the computer and software industries.

Back in the mid-80s, the National Science Foundation tried to panic Congress into a big budget boost with shrill warnings of an oncoming massive “shortfall” of scientists and engineers. Because of the “baby bust” in the 1960s, NSF forecast, student numbers would decline and the “pipeline” for science and engineering studies would suffer a loss of 675,000 bachelor degrees between 1986 and 2010. As headlines proclaimed an oncoming shortage, NSF quietly explained that “shortfall” and “shortage” were different, with shortfall merely meaning a decline from past demographic levels, while shortage meant needed workers did not exist.

As NSF and its academic friends fed the panic, a few skeptics cast doubt on the worrisome forecasts of shortage, shortfall, scarcity, and crisis. There is no foreseeable shortage of scientists and engineers, Robert M. White, president of the National Academy of Engineering, declared. A Congressional hearing brought reports of suppression of “shortfall” skeptics within NSF.

Under fire from Congress and independent workforce specialists, NSF retreated from the crisis warnings, concluding, in 1999, that “predictions of an oversupply in the 1970s did not come true, and predictions of shortages in the late 1980s also failed to occur. What is clear is that S&E positions are in a state of flux.”

The abundantly endowed Gates Foundation might attempt a useful experiment in talent supply. Advertise doubled pay for software engineers. A negligible response is not likely.