It is tempting to attribute the recent riots to the failure of the French (more broadly the Continental) economic model, in particular job protections (mandated fringe benefits, minimum wage, and tenure) that make employers reluctant to hire (because labor costs are so high and bad workers so difficult to fire). The least productive workers are hurt worst by such a system--hence the enormous unemployment rate among French of African (mainly Algerian) origin--20 percent or higher.
But the United States, with its much more open economy, has its own history of race riots. The riot in 1965 in the Watts district of Los Angeles resulted in 34 deaths. Race riots in Detroit and Newark in 1967 resulted in another 70 or so deaths. The race riots that broke out in April 1968 after Martin Luther King, Jr. was assassinated spread to 110 cities, the worst hit being Washington, D.C. And in 1992 the beating by police of Rodney King led to another major race riot in Los Angeles. The recent French riots, however, have been more widespread even than those of April 1968, though they have involved remarkably few deaths (one, at this writing) and apparently very little looting.
Riots either of the American race-riot variety or the recent French ethnic-riot variety (most Algerians are white rather than black) are mysterious phenomena. They are not concerted, and so, in contrast to political riots such as the one that occurred at the 1968 Democratic Convention in Chicago, they are difficult to understand in instrumental terms, as efforts to extract concessions from the government. Although the April 1968 race riots involved looting, the net economic effect, according to a study by economists William Collins and Robert Margo mentioned by Becker, was to depress the value of black-owned property. Undoubtedly insurance rates for stores in black neighborhoods rose as well and were passed on in part to consumers.
Other things being equal, one would expect unemployment to increase the likelihood and scope of a race riot, because the unemployed have lower opportunity costs both of rioting and of being jailed. Becker, however, cites a study that finds that the likelihood of a race riot in the United States is not correlated with black unemployment. Residential segregation can be expected to increase the likelihood of rioting, because it produces a concentration of people having similar propensities. The rioters don't have to assemble far from their homes in order to form a critical mass of rioters; the need to agree on a time and place at which to assemble would reduce the likelihood of a spontaneous riot. Poor information, which allows inflammatory rumors to spread, is still another plausible causal factor in riots; likewise youth, because young people have less aversion to risk and violence than mature people; and of course anger, which may be induced or aggravated by discrimination and inequality. But so far as economic differences between France and America are concerned that can be traced to our more open labor markets, probably the only significant one, so far as bearing on the likelihood of riots is concerned, is the much higher French unemployment rate, though even its significance is somewhat doubtful, in view of the lack of correlation between riot propensity and black unemployment in the U.S. history of race riots.
Several other differences between France and the United States may be as important as or more important than the difference in unemployment rates. One is that the French appear to have a much greater propensity to riot, or to engage in other riot-like direct action, than the citizens of other countries. French truckers and farmers are notorious for direct action, as in blocking roads, in order to enforce their demands. In 2003, a plan to reduce civil servants' pensions provoked wildcat strikes by tens of thousands of civil servants. Why the French have this propensity I don't know (it probably is not French economic policies, which are similar to those of most European countries), but it suggests a lower riot threshold than in the United States.
Another relevant consideration is that the French, like most Europeans, are much less welcoming to foreigners than Americans are. This is one reason that we have not experienced and are unlikely to experience riots by Muslims, even though there are several million of them in the United States. Direct comparison with France is difficult, however; because Muslims are a far higher proportion of the French population (roughly 10 percent to our roughly 1 percent). There is little discrimination against American Muslims, in part because most of them are solidly middle class. No doubt our free labor markets have enabled them to achieve middle class incomes. But it is possible that even if the French had free labor markets, French insularity would result in discrimination. After all, that was the U.S. experience with blacks: our race riots invariably occurred in northern states, in which blacks had the same legal access to jobs and education as whites but nevertheless were still being subjected to serious private discrimination in the prime riot era of the 1960s.
Another factor in the recent French riots may be the French refusal to engage in affirmative action. The French are reluctant even to collect statistics on the number of people in France of various ethnicities, their incomes, and their unemployment rates. No effort is made to encourage discrimination in favor of restive minorities (as distinct from women, who are beneficiaries of affirmative action in France) and as a result there are very few African-origin French in prominent positions in commerce, the media, or the government. Affirmative action in the United States took off at approximately the same time as the 1967 and 1968 race riots, and is interpretable (so far as affirmative action for blacks is concerned) as a device for reducing black unemployment, creating opportunities for the ablest blacks to rise, promoting at least the appearance of racial equality, and in all these ways reducing the economic and emotional precipitants of race riots. Of particular importance, affirmative action was used to greatly increase the fraction of police that are black, while the "community policing" movement improved relations between the police and the residents of black communities. French police, traditionally brutal, have by all accounts very bad relations with the inhabitants of the Muslim slums. The French riots are a reminder that affirmative action, although offensive to meritocratic principles, may have redeeming social value in particular historical circumstances.