Taylor's scientific management principles involve: 1) Replacing rule-of-thumb work methods with scientific time and motion studies to determine the most efficient ways to perform tasks. 2) Scientifically selecting, training, and developing each employee for their role rather than leaving training to chance. 3) Providing detailed supervision and instructions to each worker for their specific tasks. 4) Dividing work responsibilities between managers, who plan and supervise, and workers, who perform tasks.