ⓘ Moral certainty


ⓘ Moral certainty

Moral certainty is a concept of intuitive probability. It means a very high degree of probability, sufficient for action, but short of absolute or mathematical certainty.


1. Origins

The notion of different degrees of certainty can be traced back to a statement in Aristotles Nicomachean Ethics that one must be content with the kind of certainty appropriate to different subject matters, so that in practical decisions one cannot expect the certainty of mathematics.

The Latin phrase moralis certitudo was first used by the French philosopher Jean Gerson about 1400, to provide a basis for moral action that could if necessary be less exact than Aristotelian practical knowledge, thus avoiding the dangers of philosophical scepticism and opening the way for a benevolent casuistry.

The Oxford English Dictionary mentions occurrences in English from 1637.


2. Law

In law, moral or virtual certainty has been associated with verdicts based on certainty beyond a reasonable doubt.

Moral certainty, a quantum of evidence of about 100 percent proof, is required in two kinds of cases:

  • In a paternity testing case, when a putative father has been adjudicated to be the actual father by clear and convincing evidence, then moral certainty is required to disprove paternity, the onus being moved to the newly found father.
  • In a criminal prosecution, when no direct evidence exists, the circumstantial evidence must be morally certain ; see Lizzie Borden.

Legal debate about instructions to seek a moral certainty has turned on the changing definitions of the phrase over time. Whereas it can be understood as an equivalent to beyond reasonable doubt, in another sense moral certainty refers to a firm conviction which does not correlate but rather opposes evidentiary certainty: i.e. one may have a firm subjective gut feeling of guilt – a feeling of moral certainty – without the evidence necessarily justifying a guilty conviction.