Abstract
Responses of close to 2000 twelfth grade biology majors in Israel were analysed with special reference to their ability to distinguish between causal and teleological explanation. Ability to make the distinction was found to be dependent on the context, namely the knowledge base of the students and the extent to which the teleological explanations resemble everyday common sense logic. Inability to distinguish between causal and teleological explanations is considered to be the reason of students misconceptions peculiar to learning of biology. Special attention of teachers to this problem in terms of opportunties provided for students to make the distinctions while studying pertinent topics is highly recommended. There are indications that the ability to distinguish between causal and teleological explanations can be acquired with relatively little effort by students who comprehend concepts and principles commonly taught in biology classes.