However, the reaction has continually been to expand the enterprise, searching for the needle by adding more and more hay. Far overdue are extensive openly published studies that rationally evaluate homeland-security expenditures.

The NSA’s formerly secret surveillance programs have been part of the expansionary process. If they have done little to prevent terrorist attacks in the United States, and if we are now having what President Obama has characterized as a “healthy” debate about the programs, it seems reasonable to suggest that the debaters should at least be supplied with information about how much the programs cost.

Knowing the cost would scarcely help the terrorists. It might, however, amaze American taxpayers. Perhaps that’s another reason the programs have been kept secret.

These are the closing paragraphs of John Mueller and Mark G. Stewart, “3 Questions about NSA Surveillance,” The Chronicle of Higher Education, June 13, 2013. The whole piece is worth reading.

One other key paragraph:

It is difficult to see how earlier exposure of the programs’ existence would have aided terrorists, who have known at least since the 1990s that U.S. intelligence was searching communications worldwide to track them down. It is possible, however, that the secrecy of the programs stems from the Obama administration’s fear that public awareness of “modest encroachments” on privacy would make further efforts to encroach more difficult.

Basically, the gist is that the benefits of NSA surveillance have been very small and the costs have been quite large. Moreover, Mueller and Stewart bias the result against their own conclusion by understating the costs: they completely leave out the cost of NSA violating our privacy.