gument from authority (argumentum ad verecundiam): using the words of an “expert” or authority as the bases of the argument instead of using the logic or evidence that supports an argument. (e.g., Professor so-and-so believes in creation-science.) Simply because an authority makes a claim does not necessarily mean he got it right. If an arguer presents the testimony from an expert, look to see if it accompanies reason and sources of evidence behind it. Also: Look at the sources yourself! This is always a good idea, if you have time or it is important enough.
- argument from adverse consequences: (e.g., We should judge the accused as guilty, otherwise others will commit similar crimes) Just because a repugnant crime or act occurred, does not necessarily mean that a defendant committed the crime or that we should judge him guilty. (Or: disasters occur because God punishes non-believers; therefore, we should all believe in God) Just because calamities or tragedies occur, says nothing about the existence of gods or that we should believe in a certain way.
- argumentum ad baculum: An argument based on an appeal to fear or a threat. (e.g., If you don’t believe in God, you’ll burn in hell)
- argumentum ad ignorantiam: A misleading argument that exploits other people’s ignorance. (e.g: If you don’t know anything about physics, I can tell you many things about it.)
- argumentum ad populum: An argument aimed to sway popular support by appealing to sentimental or popular feelings rather than facts and reasons.
- bandwagon fallacy: concluding that an idea has merit simply because many people believe it or practice it. (e.g., Most people believe in a god; therefore, it must be true.) Simply because many people may believe something says nothing about the fact of that something. For example many people during the Black plague believed that demons caused disease. The number of believers say nothing at all about the cause of disease.
- begging the question (or assuming the answer): (e.g., We must encourage our youth to worship God to instill moral behavior.) But does religion and worship actually produce moral behavior?
- circular reasoning: stating in one’s proposition that which one aims to prove. (e.g. God exists because the Bible says so; the Bible exists because God influenced it.)
- composition fallacy: when the conclusion of an argument depends on an erroneous characteristic from parts of something to the whole or vice versa. (e.g., Humans have consciousness and human bodies and brains consist of atoms; therefore, atoms have consciousness. Or: a word processor program consists of many bytes; therefore a byte forms a fraction of a word processor.)
- confirmation bias (similar to observational selection): This refers to a form of selective thinking that focuses on evidence that supports what believers already believe while ignoring evidence that refutes their beliefs. Confirmation bias plays a stronger role when people base their beliefs upon faith, tradition and prejudice. For example, if someone believes in the power of prayer, the believer will notice the few “answered” prayers while ignoring the majority of unanswered prayers (which would indicate that prayer has no more value than random chance at worst or a placebo effect, when applied to health effects, at best).
- confusion of correlation and causation: (e.g., More men play chess than women, therefore, men make better chess players than women. Or: Children who watch violence on TV tend to act violently when they grow up.) But does television programming cause violence or do violence oriented children prefer to watch violent programs? Perhaps an entirely different reason creates violence not related to television at all. Stephen Jay Gould called the invalid assumption that correlation implies cause as “probably among the two or three most serious and common errors of human reasoning” (The Mismeasure of Man).
- excluded middle (or false dichotomy): considering only the extremes. Many people use Aristotelian either/or logic tending to describe in terms of up/down, black/white,