In this paper we extend the counterfactual simulation model (CSM)  –  originally  developed  to  capture  causal  judgments about  dynamic  events  (Gerstenberg,  Goodman,  Lagnado,  & Tenenbaum, 2014) – to explain judgments of physical support. The CSM predicts that people judge physical support by men- tally  simulating  what  would  happen  if  the  object  of  interest were removed. Two experiments test the model by asking par- ticipants to evaluate the extent to which one brick in a tower is responsible for the rest of the bricks staying on the table. The results of both experiments show a very close correspon- dence  between  counterfactual  simulations  and  responsibility judgments. We compare three versions of the CSM which dif- fer in how they model people’s uncertainty about what would have happened. Participants’ selections of which bricks would fall are best explained by assuming that counterfactual inter- ventions only affect some aspects while leaving the rest of the scene unchanged.