In the Michotte (1963) launching scenario, an object (X) moves toward a resting object (Y), eventually colliding withit. In the moment of contact, X stops und Y starts moving - creating the strong impression that X caused Y’s motion and that Xexerted a force on Y (but not vice versa). These asymmetries contradict the (symmetrical) laws of Newtonian mechanics, whichare at the heart of the popular “noisy Newton” theories of intuitive physics. As an alternative, we propose that inferences inphysical scenarios operate over pre-Newtonian representations that are based on the asymmetrical concept of impetus, a motiveforce that keeps objects moving and that is transferred and reflected in object collisions. We present a formal model of impetusand show that, unlike noisy Newton theories, it provides an explanation of asymmetrical judgments. Other related findings canalso be modeled (e.g., biases in mass judgments).

Some researchers have argued that mass perception, causal ascriptions, and predictions in simple billiard ball in-teractions can be modeled as inductive Bayesian inference over a (noisy) Newtonian representation of the world. However,there are phenomena, such as the asymmetrical ascription of forces to colliding objects, that are conceptually incompatible withthe symmetry of Newtonian physics. We propose that human inference in physical scenarios operates over a pre-Newtonianphysical representation that is based on impetus intuitions. Impetus theories assume that object movements are caused by aninternal force, impetus, that is transferred and reflected when objects collide with each other. Moreover, impetus interactionsare inherently asymmetric. We present a mathematical model that implements impetus theory and show that the theory is wellsuited to model perceived causal asymmetry. Moreover, the theory can also explain phenomena that so far have been presentedas unique evidence for (noisy) Newtonian representations.