According to the ‘collapse’ argument, episodes of mental simulation necessarily involve tacit knowledge of folk psychological generalisations. In response, I show that there is little risk that the simulation of theoretical reasoning involves such generalisations. However, the case of practical reasoning is quite different. If practical reasoning is Humean, then the risk of collapse is very great indeed. Moreover, there are compelling reasons for thinking that practical reasoning is Humean. I close by replying, qua simulationist, to the (very real) prospect of collapse.