4. Suppressed Evidence
***by Patrick J. Hurley, A concise Introduction to Logic
The fallacy of suppressed evidence is committed when an arguer ignores evidence that would tend to undermine the premises of an otherwise good argument, causing it to be unsound or uncogent. Suppressed evidence is a fallacy of presumption and is closely related to begging the question. As such, its occurrence does not affect the relationship between premises and conclusion but rather the alleged truth of the premises. The fallacy consists in passing off what are at best half-truths as if they were the whole truth, thus making what is actually a defective argument appear to be good.
The fallacy is especially common among arguers who have a vested interest in the situation to which the argument pertains.
Another form of suppressed evidence is committed by arguers who quote passages out of context from sources such as the Bible, the Constitution, and the Bill of Rights to support a conclusion that the passage was not intended to support.
To detect the fallacy of suppressed evidence, the reader or listener must be cautious that the arguer is not ignoring evidence that has a bearing on the premises. This, in turn, requires a general knowledge of the topic to which the argument pertains and a familiarity with the devices used by unscrupulous individuals to pass off half-truths as the whole truth.