When is it acceptable not to cite sources?

It is acceptable not to cite sources when the idea is widely accepted as common knowledge. Common knowledge refers to information that is generally known and undisputed in a particular field or among the general public. This includes facts that can be found in numerous sources and are not subject to dispute, such as well-known historical dates, scientific principles, or universal truths. Since this information does not require attribution, it allows writers and speakers to present it without the need for citations.

In contrast, the other options suggest conditions that would not justify a lack of citation. Finding it difficult to locate a source does not absolve a writer from the responsibility of crediting original ideas or data. Feeling confident in a viewpoint does not negate the need for supporting evidence or citations to lend credibility to that viewpoint. Similarly, paraphrasing extensively still requires citation to acknowledge the original source of the ideas, as they are not the writer's own. Thus, recognizing what constitutes common knowledge is essential to understanding when citations may not be necessary.