298 INTRODUCTION TO PHILOSOPHY OF SCIENCE 



is therefore accomplished by finding common events, i.e., 

 events which are 'now' and "here' both for myself and 

 for someone else. Practically, this can be easily done. My 

 friend and I meet in a certain room. I then tap on a table 

 and we agree that the event which is his hearing of the tap 

 is to be considered as contemporaneous with the event 

 which is my hearing of the tap. Thus by means of coexistent 

 events our two time schemes become linked together. Events 

 which are past in my friend's time system become correlated 

 with events which are past in mine, and a common time 

 begins to emerge. By extension the time systems of others 

 are introduced. Finally, a moment of absolute time becomes 

 defined as that property which is possessed in common by 

 all coexistent events; this property is called presence, past- 

 ness, or futurity, depending upon its location in some one 

 time scheme. Then, to say that an event happens at a 

 certain moment t is simply an abbreviated way of saying 

 that the event coexists with the mutually coexistent events 

 ei, e 2 , e 3 , . . . e n . Similarly, I can correlate my friend's 

 space system with mine if we can agree on an event, say 

 the table, which we shall both call "here." By means of 

 this, events which are remote in his scheme become remote 

 also in my scheme, and a common space begins to emerge. 

 As more and more time schemes are included I begin to see 

 the arbitrary character of the "here' point which has been 

 selected, and willingly replace it by the equator or one of 

 the fixed stars. Then a point of absolute space becomes 

 defined as that property which is possessed in common by 

 all events lying at a certain distance and direction from 

 some agreed-upon event; this property is called nearness, 

 or remoteness, depending upon its location in some one space 

 scheme. Accordingly, to say that an event happens at a 

 certain point p is simply an abbreviated way of saying 

 that the event has the relation R to a certain event E. In 

 this way arise the single space and the single time systems 

 which are so fruitful for science. The important point to 

 recognize, since reference will be made to it later, is that the 



