- Opponents of the Iraq war have the support of one of the two major political parties. They thus have less reason to feel abandoned and more hope that their goals will be achieved through the regular political process. They also may be reluctant to jeopardize the efforts of Democratic Party politicians.
- The opportunity costs are higher today: wages are higher (especially for the highly educated), more women work, and the greater competitiveness in the economy means that a reputation as a violent protester poses a higher risk to one's career.
- Blogs and other electronic media provide alternative outlet and support networks.
- People learned from earlier mistakes: Vietnam protests probably didn't end the war, but they did help Nixon become president.
- Vietnam protests were also about the system in general; there was a revolutionary or Utopian element then. In contrast, most people today believe strongly in the American political and economic system in principle.
That's some food for thought, and all of Posner's reasons deserve to be taken seriously. But they should also be scrutinized. Are they factually correct? Can they explain the lack of outrage in other recent situations that might have resulted in mass protests, such as the stolen 2000 presidential election? (Obviously, the draft and the number of casualties do not apply there, so Posner's reasons should only be more important.) And finally, if Posner is right, what are the broader implications? Should we be happy about what we learned?
Factually, Posner seems mostly correct, except that, for most people, real wages are not much higher now than in 1968, and it is likely that the protests did speed up the end of the war, although we'll never know for sure.
As for explaining the lack of outrage over the 2000 election, I can only see #2 as a convincing factor, although it is far short of a full explanation. The Democratic Party did not rock the boat, blogs hardly existed, there were few, if any, related past mistakes to learn from, and a belief in the American system of government might have been an additional reason to protest. (On the other hand, the belief in the system could also have resulted in the Gore position - accepting the decision despite strongly disagreeing with it - but at least the net effect is ambiguous.)
I suspect there is an additional cultural reason - that Americans have become more risk-averse. That would be consistent with the observed changes in other areas, from school safety rules to product liability lawsuits. Admittedly, that same change in attitudes makes us more sensitive to the military deaths (so 3,000 in Iraq feel closer to 60,000 in Vietnam than the raw numbers suggest), but the aversion to relatively small personal losses (like time and career prospects) has apparently grown more than the aversion to risking lives. Other people's lives, that is, which brings the draft issue back into play.
Finally, I find Posner's reason #2 troubling. There is no causal connection between a more competitive economy and career risk for protesters. If someone has been a protester, can we infer that that person is likely to be less productive? Certainly, there are traits that make one both a likely protester and a productive worker; for example, enthusiasm, initiative, and willingness to take risks. There must be something other than competitive economy that creates the link between protests and career risks, and that something does not look benign.
UPDATE: Posner addresses some readers' comments here.