David Hume explained that we believe by habit that logs will burn, stones will fall, and endless other past patterns will recur. No experiment can prove the future recurrence of past events. An experiment belongs to the future only until it is implemented; once completed, it becomes part of the past. In order for past experiments to prove something about the future, we must assume that the past will recur in the future. That's as circular as it gets.
But without the habit of believing that past patterns will recur, we would be incapacitated and ineffectual (and probably reduced to moping and sobbing). Who would dare climb stairs or fly planes or eat bread and drink wine, without the belief that, like in the past, the stairs will bear our weight, the wings will carry us aloft, and the bread and wine will nourish our body and soul. Without such habits we would become a jittering jelly of indecision in the face of the unknown.
But you can't just pull a habit out of a hat. We spend great effort instilling good habits in our children: to brush their teeth, tell the truth, and not pick on their little sister even if she deserves it.
As we get older, and I mean really older, we begin to worry that our habits become frozen, stodgy, closed-minded and constraining. Younger folks smile at our rigid ways, and try to loosen us up to the new wonders of the world: technological, culinary or musical. Changing your habits, or staying young when you aren't, isn't always easy. Without habits we're lost in an unknowable world.
And yet, openness to new ideas, tastes, sounds and other experiences of many sorts can itself be a habit, and perhaps a good one. It is the habit of testing the unknown, of acknowledging the great gap between what we do know and what we can know. That gap is an invitation to growth and awe, as well as to fear and danger.
The habit of openness to change is not a contradiction. It is simply a recognition that habits are a response to the unknown. Not everything changes all the time (or so we're in the habit of thinking), and some things are new under the sun (as newspapers and Nobel prize committees periodically remind us).
Habits, including the habit of open-mindedness, are a good thing precisely because we can never know for sure how good or bad they really are.