Similarly, the act of standing up from a chair could be interrupted by factors beyond our knowledge or control. The chair may spontaneously collapse, or our muscles and ligaments may not work as we expect them to, or there may be a sudden change in atmospheric pressure or gravity that makes it impossible to stand up. Granted, some of these situations are more far-fetched than others, but none of them is out of the realm of possibility, and all are beyond the scope of human control.
