Various theories can be proposed ....
Fact
Pfaff... is convinced that...
Fact
Against the odds, both survived.
Fact
... it might lead us to draw an opposite conclusion...
Opinion
He good deed can be interpreted as heroic.
Opinion
All of which suggests to Pfaff that...
Opinion
He maintains that this view is now generally accepted
Opinion
Some of the extra neutrons gained are most likely...
Opinion