The place of evidence regarding joint commitment and plural action is mostly reserved for documents and explicit linguistic expressions. This paper considers the problem of evidence in cases of engaged (jointly committed) social acts where there is no explicit expression or binding document, yet can still be ascribed to a plural subject. The argument rests on the double meaning of the term factum as fact (factum brutum) and deed (factum practica), as well as contemporary debates about the topic of fact (...) of reason in Kant. The text seeks to show that in certain cases, the execution of an act or the obligation produced by it can be considered evidence of a plural subject. Thus, these facts deserve a special position in relation to scientific evidence. (shrink)