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The term you want is verisimilitude. Basically, you want to avoid breaking the readers suspension of disbelief. This means that what happens must be consistent to the rules of what can happen that...
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Source: https://writers.stackexchange.com/a/15900 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
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The term you want is [verisimilitude](http://en.wikipedia.org/wiki/Verisimilitude_%28narrative%29). Basically, you want to avoid breaking the readers suspension of disbelief. This means that what happens must be consistent to the rules of what can happen that the reader has accepted for the setting. If the story is set in the real world, this is close, but not identical, to realism. You'd still be expected to adhere to genre conventions even if the story is set in the real world. Even in fictional world the genre matters, for example in science fiction you are expected to warn the readers of the changed parts in advance, in fantasy having the setting consistent with itself is sufficient. In fact, regardless of genre the setting must be self-consistent, but usually it is not necessary to make specific effort because your own experience of how the real world works helps you.