逻辑谬误是一种推理错误，使论点无效。它也被称为谬误、非正式逻辑谬误和非正式谬误。所有的逻辑谬误都是非对等的论点，在这些论点中，一个结论在逻辑上并不遵循它之前的结论。

临床心理学家Rian McMullin扩展了这一定义：

"Logical fallacies are unsubstantiated assertions that are often delivered with a conviction that makes them sound as though they are proven facts. ...Whatever their origins, fallacies can take on a special life of their own when they are popularized in the media and become part of a national credo" (The New Handbook of Cognitive Therapy Techniques, 2000)

实例和意见

“逻辑谬误是通过歪曲问题、得出错误结论、滥用证据或滥用语言来削弱论点的错误陈述。”

（Dave Kemper等人，《融合：综合读写》。圣吉，2015年）

避免逻辑谬误的理由

“有三个很好的理由可以避免你写作中的逻辑谬误。首先，逻辑谬误是错误的，简单地说，如果你有意使用它们，那就是不诚实的。第二，他们剥夺了你论点的力量。最后，使用逻辑谬误可以让读者觉得你不认为他们是非常聪明的。”

（威廉R。斯马尔泽，“为阅读而写：阅读、反思和写作，第二版”，剑桥大学出版社，2005年）

"Whether examining or writing arguments, make sure you detect logical fallacies that weaken arguments. Use evidence to support claims and validate information—this will make you appear credible and create trust in the minds of your audience." (Karen A. Wink, "Rhetorical Strategies for Composition: Cracking an Academic Code." Rowman & Littlefield, 2016)

非正式谬误

“尽管有些论点是如此明显的谬误，至多可以用来取笑我们，但许多论点更微妙，难以识别。一个结论似乎常常从真实前提出发，合乎逻辑且不平凡，只有仔细研究才能揭示论点的谬误。

这种貌似谬误的论点被称为非正式谬误，它可以在很少或根本不依赖形式逻辑方法的情况下被认为是谬误

（R。鲍姆，“逻辑”，哈考特，1996年）

正式谬误和非正式谬误

逻辑错误主要有两类：形式错误和非正式错误。

“形式”一词指的是一个论点的结构和最关注结构演绎推理的逻辑分支。所有形式谬误都是演绎推理中的错误，导致论点无效。术语“非正式”指的是论点的非结构性方面，通常在归纳推理中强调。大多数非正式谬误都是归纳错误，但其中一些谬误也适用于演绎论点。

（Magedah Shabo，“修辞、逻辑和论证：学生作家指南”，《普雷斯特维克之家》，2010年）

逻辑谬误的例子

“你反对一位参议员提出的将政府资助的医疗保健扩展到贫困少数民族儿童的建议，因为这位参议员是自由民主党人。这是一种常见的逻辑谬论，被称为ad-homeem，拉丁语表示“反对男人”。你没有处理这个论点，而是通过基本上说“我不能听任何不认同我的社会和政治价值观的人的话”来抢占任何讨论的先机。你确实可以决定你不喜欢参议员正在提出的论点，但你的工作是在争论中挖洞，而不是进行人身攻击。”

（德里克·索莱斯，《学术写作要领》，第二版，沃兹沃斯，2010）

"Suppose that each November, a witch doctor performs a voodoo dance designed to summon the gods of winter and that soon after the dance is performed, the weather, in fact, begins to turn cold. The witch doctor's dance is associated with the arrival of winter, meaning that the two events appear to have happened in conjunction with one another. But is this really evidence that the witch doctor's dance actually caused the arrival of winter? Most of us would answer no, even though the two events seem to happen in conjunction with one another. "Those who argue that a causal relationship exists simply because of the presence of statistical association are committing a logical fallacy known as the post hoc propter ergo hoc fallacy. Sound economics warns against this potential source of error." (James D. Gwartney et al., "Economics: Private and Public Choice," 15th ed. Cengage, 2013) "The arguments in support of civic education are often seductive.... "Although we might emphasize different civic virtues, don't we all honor a love for our country [and] a respect for human rights and the rule of law.... Since no one is born with an innate understanding of these virtues, they must be learned, and schools are our most visible institutions for learning. "But this argument suffers from a logical fallacy: Just because civic virtues must be learned, does not mean they can be easily taught—and still less that they can be taught in schools. Nearly every political scientist who studies how people acquire knowledge and ideas about good citizenship agrees that schools and, in particular, civics courses have no significant effect on civic attitudes and very little if any, effect on civic knowledge." (J. B. Murphy, The New York Times, September 15, 2002)