Their arguments would deserve more of a hearing if, instead of declaring their contentions as fact, they instead coughed up some evidence to support their claims.
One argument that is repeated again and again is that killing terrorists with drones generates resentment from Pakistan to Yemen, thereby breeding many more terrorists than are killed. For example, Akbar Ahmed, a distinguished professor at American University, told the BBC on April 9 that, for "every terrorist drones kill, perhaps 100 rise as a result."
The key word is "perhaps"; Ahmed cites no data to support his contention.
Similarly, in The New York Times, Jo Becker and Scott Shane write that "Drones have replaced Guantanamo as the recruiting tool of choice for militants," citing as their evidence one line Faisal Shahzad, who had tried to set off a car bomb in Times Square, used in his 2010 trial seeking to justify targeting civilians.
At the same time, when HBO interviewed children who carry suicide vests, they justified their acts by the presence of foreign troops in their country and burning of Korans.
No such self-serving statements can be taken as evidence in themselves.
And Peter Bergen, a responsible and serious student of drones, quotes approvingly in The Washington Post a new book by Mark Mazzetti, who claims that the use of drone strikes "creates enemies just as it has obliterated them." Again, however, Mazzetti presents no evidence.
One may at first consider it obvious that, when American drones kill terrorists who are members of a tribe or family, other members will resent the United States. And hence if the United States would stop targeting people from the skies, that resentment would abet and ultimately vanish.
In reality, ample evidence shows that large parts of the population of several Muslim countries resent the United States for numerous and profound reasons, unrelated to drone attacks.
These Muslims consider the United States to be the "Great Satan" because it violates core religious values they hold dear; it promotes secular democratic liberal regimes; it supports women's rights; and it exports a lifestyle that devout Muslims consider hedonistic and materialistic to their countries.
These feelings, data show, are rampant in countries in which no drones attacks have occurred, were common in those countries in which the drones have been employed well before any attacks took place, and continue unabated, even when drone attacks are greatly scaled back.
As Marc Lynch notes in Foreign Affairs:
"A decade ago, anti-Americanism seemed like an urgent problem. Overseas opinion surveys showed dramatic spikes in hostility toward the United States, especially in the Arab world ... It is now clear that even major changes, such as Bush's departure, Obama's support for some of the Arab revolts of 2011, the death of Osama bin Laden, and the U.S. withdrawal from Iraq, have had surprisingly little effect on Arab attitudes towards the United States. Anti-Americanism might have ebbed momentarily, but it is once again flowing freely."
The Pew Global Attitudes Project says anti-American sentiments were high and on the rise in countries where drone strikes weren't employed. In Jordan, for example, U.S. unfavorability rose from 78 percent in 2007 to 86 percent in 2012 while Egypt saw a rise from 78 percent to 79 percent over the same period.
Notably, the percentage of respondents reporting an "unfavorable" view of the United States in these countries is as high, or higher, than in drone-targeted Pakistan.
In Pakistan, a country that has been subjected to a barrage of strikes over the last five years, the United States' unfavorability held steady at 68 percent from 2007-10 (dropping briefly to 63 percent in 2008), but then began to increase, rising to 73 percent in 2011 and 80 percent in 2012 -- a two-year period in which the number of drone strikes was actually dropping significantly.
It is also worth noting that these critics attribute resentment to drones rather than military strikes.
Do they really think that resentment would be lower if the United States were using cruise missiles? Or bombers? Or Special Forces?
If they mean that we should grant these suspected terrorists a free pass if they cannot be brought to a court in New York City to be tried, they should say so.
Another frequent claim of drone opponents is that the use of drones greatly lowers the costs of war (at least for the United States) and, thus, promotes military adventurism.
For example, Mazzetti (as quoted by Bergen) claims that the use of drones has "lowered the bar for waging war, and it is now easier for the United States to carry out killing operations at the ends of the earth than at any other time in its history."
However, there is no evidence that the introduction of drones (and before that, high-level bombing and cruise missiles that were criticized on the same grounds) made going to war more likely or its extension more acceptable.
On the contrary, anybody who followed the American disengagement in Vietnam after the introduction of high-level bombing (which was subject to criticism similar to that of drones) or the U.S. withdrawal from Afghanistan -- despite the considerable increase in the use of drone strikes elsewhere -- knows better.
In effect, the opposite argument may well hold: If the United States couldn't draw on drones in Yemen and the other new theaters of the counterterrorism campaign, the nation might well have been forced to rely more on conventional troops, a choice that would greatly increase our casualties as well as the resentment by the locals, who particularly object to the presence of foreign troops.
Finally, critics argue that many of those killed by drones are "low-ranking militants." Well, so were the 19 men who brought down the World Trade Center and hit the Pentagon, and terrorized a nation with an attack from which we have yet to recover and which brought us to Afghanistan in the first place.
(Amitai Etzioni is the author of "Hot Spots: American Foreign Policy in a Post-Human-Rights World," the director of the Institute for Communitarian Policy Studies and a professor of International Affairs at the George Washington University.)
(United Press International's "Outside View" commentaries are written by outside contributors who specialize in a variety of important issues. The views expressed do not necessarily reflect those of United Press International. In the interests of creating an open forum, original submissions are invited.)