 A proper notion of backward causation requires that the future is just as real as the present and the past. It is common among metaphysicians to distinguish between three different views on time. The first is presentism. This view claims that only events that exist now really exist. Past or future events do not exist. Past events have ceased to exist, whereas future events are yet to become real. So only statements about the present or related to the present have a definite truth value. The second view is possibilism according to which both past and present events exist, but future events are still only possible or non-existing. This view is sometimes called the growing block universe. As a consequence, the view holds that only statements about past and present events have a definite truth-value, but statements about the future are either probably true or may completely lack any truth-value. Finally, the third view is called eternalism, also named the block universe. This position maintains that every past, present and future event tenselessly exists at a certain time and that statements about these events therefore have a definite truth-value at every other time.