He and the children conclude that their world diverged from 12B (ours) by a particular historical accident. They work to outwit the local inquisition and to merge their history, thus their world, with ours.
He and the children deduce that their world diverged from 12B (ours) due to a specific historical event. They strive to outsmart the local inquisitors and merge their history with ours, thereby integrating their world into ours.