Algorithms are, as the mathematician Cathy O’Neil once said, opinions encoded in numbers. They impose subjective assumptions on data that’s skewed and incomplete.
Unique or rare external events may render what was formerly predictable suddenly unforeseeable, making historical data irrelevant or useless. (This is frequently true of epidemics.)
And finally there is the problem of life itself: the tendency of organisms, atoms and subatomic particles to behave in non-random but fundamentally unpredictable ways.
From the book, Uncharted: How to Map the FutureMargaret Heffernan