The future is open and uncertain. Philosophers have devoted little attention to this realisation, so banal does it seem. However, according to Immanuel Kant, people do have free will; you may dictate in advance what an individual should do, but you cannot predict what they actually will do (see "The Conflict of the Faculties", 1794, Second Section; I thank Otfried Höffe for the reference). In short, the future is not predictable. There are of course laws of nature, such as gravity. If you throw a ball, for example, you can be fairly certain that it will fall to the ground – unless someone intercepts it (volleyball players, of course, could write a book on this subject).