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 supporta statement of what those appropriate conditions arethe sentence is true but incontestable. A statement which is true by definition (for example, the Lapalissade "If he were not dead, he would still be alive") 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.
Longman Dictionary of Contemporary English
The Collaborative International Dictionary
Truism \Tru"ism\, n. [From True.] An undoubted or self-evident truth; a statement which is pliantly true; a proposition needing no proof or argument; -- opposed to falsism.
Trifling truisms clothed in great, swelling words.
--J. P. Smith.
Douglas Harper's Etymology Dictionary
n. 1 A self-evident or obvious truth. 2 A banality or cliché.
n. an obvious truth
Usage examples of "truism".
Since the durian is endemic in a very restricted portion of the globe, and since those who have watched the vital process may be comparatively few in number and therefore unlikely to be jaded by the truisms of these pages, a few words in explanation may not be resented.
The very lies of Dublin and Belfast are truer than the truisms of Westminster.
This is not a paradox but a plain truism, which can only be missed by those who may know what is meant by an Aristotelian, but have simply forgotten what is meant by a Christian.
Firing lightning bolts in all directions just to share his happiness with the world, ranting that he had just accomplished what Ock and Venom and The Green Goblin and Doctor Doom had never been able to do, and at the same time rehearsing the witty romantic badinage that would burble from his suave lips as he squired the lovely Pity hither and yon, he embodied not just his usual sociopathy but also the truism that love makes fools of us all, especially for those of us who already happen to be far from the swiftest bulbs in the marquee.
What goes around, comes around--an ecological truism as painful as constipation.
Even we sooners know one of the basic truisms of life in the Five Galaxies If something isn't in the Library, it is almost certainly impossible.
Except that Gonzales was getting a late report from the front that could rewrite mid-twenty-first century truisms about the nature of machine intelligence.
In SF it has always been fatally easy to shrug off such truisms to dwell on the trivialities of SF as a career: the daily grind in the Old Baloney Factory.
The authors of these pseudo-scientific fairy tales supply the public with what it wants: truisms, cliches, stereotypes, all sufficiently costumed and made "wonderful" so that the reader may sink into a safe state of surprise and at the same time not be jostled out of his philosophy of life.
To those who are familiar with the original, it savours of truism or platitude to say so, for in truth there can be no thoroughly satisfactory translation of "Don Quixote" into English or any other language.
The aspect in question is the reduction of what used to be regarded as physical laws to the status of truisms or definitions.
So let me return to you one of your own truisms: 'Adaptation is the keynote of survival' Let it not be said that Kanizar's too old a beast to contemplate adaptation.