If the input data was perfectly self-consistent, "all data" could be considered "reality". In reality, "all data" is rife with disagreement, which you have to p

If the input data was perfectly self-consistent, "all data" could be considered "reality". In reality, "all data" is rife with disagreement, which you have to perceive as noise (and get noisy output) or value-judge contradicting opinions, getting, no surprise, biased output.