"One of these aspects of existence which we arbitarily believe in is cause and effect . Another is the external world . A third is the consciousness of others . A fourth is the past etc . etc ."
"They originally might have been an arbitrary guess , but experience of all humans always has given them a very high probability of being true ( at least the existence of the outside world , the others are abstract logical concepts that do n't have a physical reality , just an abstract one ) ."
"arbitarily consciousness past etc . etc ."
"arbitrary guess probability of being outside world abstract logical just an abstract one"