Data
In Debate, we need data, or evidence, to be effective. Evidence can take many forms: statistics, expert testimony, and specific examples are some of the most common. Because speakers are not established experts, they cannot simply argue for a position; no matter how reasonable their arguments may be. Thus, debaters must conduct extensive research to prepare for the topics they will debate.
In an ideal situation, evidence would be provided whenever the speaker makes a claim about the world; in the limited time of a debate speech, however, she must make choices about when to provide evidence and when to cite sources. Speakers would cite a source for two reasons. First, and most obviously, they should never present the ideas of any other person as their own; plagiarism is as serious an issue in a debate speech as it is in an essay. If a speaker is using a quotation or argument from a particular source, he must attribute it to that source. Additionally, if the information is likely to be challenged, the speaker should provide a citation.
Source citations are not necessary when ideas or data are so widely available that they are common knowledge. One rule of thumb is that if a piece of data can be found in 10 different sources, a citation is not necessary because no one is likely to challenge the information and because the information can be said to be part of the public domain. In fact, not citing a source in this situation may be to a speaker’s benefit: by citing a source, the speaker is suggesting that he did not know the information and had to do research to find it. This may be true, but it does not establish credibility. To establish themselves as well-read, speakers should present commonly available information as accepted fact.