The surprising success of a replication that failed

In a recent paper, Oliver Will (2009) contends that the effect of mobility on trust that we originally reported (Macy and Sato 2002) depends on 'an assumption that is most probably an unwilling, unintended, and unwanted implication of the code.' When we experimented with Will's revised model, we came to the opposite conclusion: his version provides stronger support for our theory than does our original. The explanation is that Will left the learning rate at the upper limit of 1.0, the level we assumed in our original paper. When we lowered the learning rate to compensate for the removal of the contested assumption, the results showed how mobility can lead to an increase in trust, which is consistent with our explanation for higher trust in the US compared to Japan. Moreover, the model also shows that it is possible for there to be too much mobility.