n8 SCIENTIFIC METHOD IN PHILOSOPHY 



one event A, we take two events A and B, and suppose 

 A and B partly overlap, but B ends before A ends. 

 Then an event which is simultaneous with both A and B 

 must exist during the time when A and B overlap ; thus 

 we have come rather nearer to a precise date than when 

 we considered A and B alone. Let C be an event which 

 is simultaneous with both A and B, but which ends before 

 either A or B has ended. Then an event which is simul- 

 taneous with A and B and C must exist during the time 



when all three 

 overlap, which is 

 a still shorter 

 g time. Proceed- 



ing in this way, 

 by taking more 



q and more events, 



a new event which 

 is dated as simultaneous with all of them becomes gradu- 

 ally more and more accurately dated. This suggests a 

 way by which a completely accurate date can be defined. 



Let us take a group of events of which any two overlap, 

 so that there is some time, however short, when they all 

 exist. If there is any other event which is simultaneous 

 with all of these, let us add it to the group ; let us go 

 on until we have constructed a group such that no event 

 outside the group is simultaneous with all of them, but 

 all the events inside the group are simultaneous with 

 each other. Let us define this whole group as an instant 

 of time. It remains to show that it has the properties we 

 expect of an instant. 



What are the properties we expect of instants ? First, 

 they must form a series : of any two, one must be before 

 the other, and the other must be not before the one ; if 

 one is before another, and the other before a third, the 



