In 1989, Marc Lépine walked into the École Polytechnique in Quebec.
He went into an engineering class and pulled out a semi-automatic rifle.
He separated the male students from the female.
He told the male students to go, and the female students to stay.
Then he shot all the female students, yelling: "I hate feminists."
Then he wandered through the college, shouting he hated feminists, and shot another 14 female students.
He killed one young woman with his hunting knife when his gun jammed.
Four male students were injured in the crossfire.
Then Lépine shot himself.
Altogether, he shot 28 female students – 14 died.
You would have thought it was obvious, the shootings were about women.
But media commentators didn’t agree – they said he was a madman and the women just happened to be in the way.
In fact, a psychiatrist at the Hotel-Dieu hospital said that Lépine was "as innocent as his victims, and himself the victim of a merciless society".
Nathalie Provost, one of the women he shot, said: "He told us we were there because we were feminists, then he started shooting."
But it made no difference – the media had decided on their own truth.
The police abetted by refusing to release Lépine’s suicide note.
Eventually someone leaked it to journalist Francine Pelletier.
In it were the names of 19 prominent feminists Lépine intended to kill – Pelletier’s name was on the list.
He wrote: "I have decided to send the feminists who have ruined my life to their maker. I have decided to put an end to these viragos."
But even that couldn’t change the minds that were already made up.
One of them, Barbara Frum, said: "This should not be seen as an attack or violence against women. Why must people diminish it by suggesting it was an act against just one group?"
Incredibly, when people are determined to believe something, no evidence can shift their belief.
It’s called denial bias.
These people had decided that a massacre of women was not helpful to their position.
Their position was that women would no longer be seen as separate.
Therefore, this must be a crime against people.
Seeing it as a crime against women didn’t fit their position, so they changed the facts to fit their position.
They didn’t want a crime against women, they wanted a crime against people.
That’s my problem with positions and predictions.
Predictions are usually based on reinterpreting what’s happening now.
That’s what gives the prediction its credibility.
So what’s happening now must be reinterpreted to fit the prediction.
Which, for me, is like predicting the future by looking in the rear-view mirror.
Dave Trott is the author of Creative Mischief, Predatory Thinking and One Plus One Equals Three.