The presentation introduces a peculiar medieval attempt to reconsider the traditional Aristotelian classification of four causes. According to some medieval philosophers (13th century Franciscan thinker Peter Olivi is of particular importance here), there is a special type of cause ? the so-called ?terminative cause? (causa terminativa) which has no counterpart among the traditional four causes. Such a cause was postulated to explain the problem of ascendant causality, i.e. the question how ontologically inferior entities (such as material objects) can exert causal influence on the ontologically superior ones (such as souls and their cognitive powers). The presentation inquiries into the question whether this notion of causa terminativa constitutes a special, fifth type of causality, or is reducible to one of the four traditional ones.