In 2003 in a Supreme Court of Appeal (Stellenbosch Farmers’ Winery v Patel) matter the above question was discussed:
A court must make findings on credibility of factual witnesses, on their reliability and on probabilities.
In terms of the credibility, the court creates an impression of the veracity of the witnesses. This is done by considering their demeanour, biases, internal and external contradictions, probability of their version, calibre and the potency of their version compared to other witnesses.
In terms of reliability, the court considers the opportunities the witnesses had to experience the event in question and the witnesses’ quality and integrity of their report of the event.
In terms of probabilities, the court analyses and evaluates the probability of each party’s version. The party with the burden of proof must discharge his/her burden.