Heinlein's quote is non-sense.
Decisions and assessments that are made by the 'preponderance of evidence' criteria the discernment maker has faith and acts on that faith until new evidence is sufficient to prove otherwise.
Decisions and assessments that are must be made by the 'beyond a reasonable doubt' criteria are the same, the maker has faith and acts on that faith until new evidence is sufficient to prove otherwise. But usually such decisive action cannot be undone, but that is just the way it is.