Where the language of a written contract is ambiguous, evidence is admissible to construe its meaning, by reference to its context or the factual circumstances under which the contract was concluded. The apparent purpose to which the contract was directed may also be considered when interpreting it. Evidence may be admitted as to what was probably in the minds of the parties when the agreement was concluded. Courts will look for a sensible and business-like result, as the supreme court of appeal did in X-Procure Software SA (Pty) Ltd v Sutherland.
But the same court warned in Braun Medical (Pty) Limited v Ambasaam CC that, to the extent that evidence may be admissible to contextualise a document to establish its factual circumstances or purpose or context, the evidence must be used as conservatively as possible.
Ambiguity may not be difficult to find. In The Commissioner for SARS v Bosch the court pointed out that the words of a section of statute may in rare cases be capable of bearing only a single meaning. Outside of that situation it is pointless to speak of a statutory provision or clause in a contract as having a plain meaning. One meaning may strike the reader as dramatically more plausible than another. But, as soon as more than one possible meaning is available, the determination of the proper meaning will depend as much on context, purpose and background as on dictionary definitions.