Critics suggest that it is not a testable hypothesis, and nor does it follow logically that dynamic density would cause this new type of solidarity, supposing it actually existed.
"Already Adam Smith had pointed to sufficient demand as a necessary condition for specialization, and Durkheim himself refers to Comte for the idea that density of interaction is the decisive factor [for transition to occur]."
(Gibbs, 2003) They need to exist in symbiosis with other species, like the bees that fertilize the plants they consume, in order to thrive in greater numbers.
The first is mechanical solidarity, where people are held together because they all serve the same purpose, or do the same things (as in a hunter-gatherer society), and their collective consciousness is therefore very strong.
With the growth of dynamic density and resulting division of labor in society, collective consciousness is weakened severely and people no longer have a unified sense of morality.
Robert K. Merton argues that Durkheim has no empirical evidence supporting a link between dynamic density and a change from mechanical to organic solidarity.
(Merton, 1994) Jack Gibbs also says that Durkheim's theory of dynamic density leading to the division of labor is not scientifically testable for or evident of causality, arguing that there is no feasible way to measure the frequency of interactions between people, and thus no way to track progress or growth of said frequency; without these measurements, it is impossible to prove any correlation to division of labor.