The Cassandra metaphor (variously labelled the Cassandra 'syndrome', 'complex', 'phenomenon', 'predicament', 'dilemma', or 'curse') occurs when valid warnings or concerns are dismissed or disbelieved.
The term originates in Greek mythology. Cassandra was a daughter of Priam, the King of Troy. Struck by her beauty, Apollo provided her with the gift of prophecy, but when Cassandra refused Apollo's romantic advances, he placed a curse ensuring that nobody would believe her warnings. Cassandra was left with the knowledge of future events, but could neither alter these events nor convince others of the validity of her predictions.
The metaphor has been applied in a variety of contexts such as psychology, environmentalism, politics, science, cinema, the corporate world, and in philosophy, and has been in circulation since at least 1949 when French philosopher Gaston Bachelard coined the term 'Cassandra Complex' to refer to a belief that things could be known in advance.