Full Idea
If any number of pasts are compatible with the present state of affairs, and it is only the present state of affairs which can make true or false statements about the past, then no statement about the past is either true or false.
Gist of Idea
If the present could have diverse pasts, then past truths can't have present truthmakers
Source
Robin Le Poidevin (Travels in Four Dimensions [2003], 08 'First')
Book Reference
Le Poidevin,Robin: 'Travels in Four Dimensions' [OUP 2003], p.138
A Reaction
He suggests an explosion which could have had innumerable different causes. The explosion could have had different origins, but not sure that the whole of present reality could. Presentists certainly have problems with truthmakers for the past.