A truism is a claim that is so obvious or self-evident as to be hardly worth mentioning, except as a reminder or as a rhetorical or literary device, and is the opposite of falsism.
In philosophy, a sentence which asserts incomplete truth conditions for a proposition may be regarded as a truism. An example of such a sentence would be “Under appropriate conditions, the sun rises.” Without contextual support – a statement of what those appropriate conditions are – the sentence is true but incontestable. A statement which is true by definition (“All cats are mammals.”) would also be considered a truism. This is quite similar to a tautology in which the conclusion of a statement is essentially equivalent to its premise, a statement that is “true by virtue of its logical form alone”.
The word may also be used with a different sense in rhetoric, to disguise the fact that a proposition is really just an opinion. Similarly, stating an accepted truth about life in general can also be called a truism.
A Truism is a statement of the obvious. In the Milton Model truisms are used as part of hypnotic language patterns to produce a false cause and effect. The client listens to the first truism statement, and agrees with it. The client listens to the next truism, and agrees with that too. The next suggestion is then made while the agreement with the truism is still in mind, so it too will be accepted as true, even if it has nothing to do with the first statements and is not a truism.