 McTaggart argues for premise (3) by attempting to demonstrate that the existence of the A-series would generate a contradiction. According to McTaggart, being present, being past, and being future are incompatible determinations. But everything in time must have each of them. How best to reconstruct the  rationale for this premise is highly  contentious.[9]  The intuitive picture seems to be this. Consider an event that from our perspective is past. Perhaps it is the event of McTaggart first considering the unreality of time. From the perspective of that event, it is present (and we are future). However, the ordering generated by the A-series is supposed to be an objective ordering: an A-series is not thereby generated simply by one’s arbitrary choice of a point of time as the present. Since the respective situations are symmetrical, there is no reason to prefer one perspective over the other. If we take both perspectives as being correct, then we must say of some event (and every event by parity of reasoning) that it is past, present, and future. So instead we should say that neither perspective is correct, and that the A-series does not exist.