Originating in the legal profession, argument in the alternative is a strategy in which a lawyer advances several competing (and possibly mutually exclusive) arguments in order to pre-empt objections by his adversary, with the goal of showing that regardless of interpretation there is no reasonable conclusion other than the advocate's.
[1] The notion is closely related to alternative pleading, and the two terms are sometimes used interchangeably.
The secondary line of reasoning might be presented to persuade a sub-audience who would not otherwise agree with the primary argument.
In a particular case it may be best for the plaintiff to allege that a statement made was to become a term of the contract.
[3] Occasionally, such arguments can be confusing to some people, who perceive a self-contradiction or lack of honesty.