 Popper disapproved thoroughly of Kuhn’s demarcation criterion. According to Popper, astrologers are engaged in puzzle solving, and consequently Kuhn’s criterion commits him to recognize astrology as a science. (Contrary to Kuhn, Popper defined puzzles as “minor problems which do not affect the routine”.) In his view Kuhn’s proposal leads to “the major disaster” of a “replacement of a rational criterion of science by a sociological one” (Popper 1974, 1146–1147).