“The first principle is that you must not fool yourself and you are the easiest person to fool.”
— Richard P. Feynman
Persuasion is a function of feeling and logic. To improve our lot, it's important we learn to use language effectively, and understand the common errors in reasoning that keep us from arguing well. Common sense, after all, is not that common.
Fallacies can either be formal or informal. We can see the first in the argument's form-- for example, using personal experience or an isolated example instead of sound reasoning or compelling evidence, or collapsing a universal premise into a particular conclusion.
To identify the second we need to examine the argument's content -- for example, dismissing a claim as absurd without demonstrating proof for its absurdity, or a favorite of public discourse, the evasion of the actual topic by directing an attack at your opponent.
Early in his career, Ali Almossawi spent some time writing software specifications using first-order predicate logic. The task helped him develop an appreciation for the precise reasoning and rigor of using discrete mathematics. As he says in the preface of An Illustrated Guide of Bad Arguments,
During the same time, I perused a few books on propositional logic, both modern and medieval, one of which was Robert Gula's A Handbook of Logical Fallacies. Gula's book reminded me of a list of heuristics that I had scribbled down in a notebook a decade ago about how to argue; they were the result of several years of arguing with strangers in online forums and had things like, “try not to make general claims about things.” That is obvious to me now, but to a schoolboy, it was an exciting realization.
It quickly became evident that formalizing one's reasoning could lead to useful benefits such as clarity of thought and expression, objectivity and greater confidence. The ability to analyze arguments also helped provide a yardstick for knowing when to withdraw from discussions that would most likely be futile.
Robert Gula's Nonsense: Red Herrings, Straw Men and Sacred Cows: How We Abuse Logic in Our Everyday Language is an easy read and a handy compilation and study of verbal logical fallacies to complement Almossawi's Illustrated Guide. The Guide contains a one-page explanation each of the following arguments and an illustration of the concept:
- Argument from consequences -- when we speak for or against the truth of a statement appealing to the consequences of accepting or rejecting it, engaging our hopes or fears
- Straw man -- misrepresenting, misquoting, misconstruing and oversimplifying are all examples of attacking a caricature instead of the real argument
- Appeal to irrelevant authority -- when the appeal is to an authority who is not an expert on the issue at hand, for example
- Equivocation -- exploits the ambiguity of language by changing the meaning of a word during the course of an argument and using the different meanings to support some conclusion
- False dilemma (or the black & white fallacy) -- an argument that presents a set of two possible categories and assumes that everything in the scope of that which is being discussed must be an element of that set. However, in life we know there are more than two doors
- Not a cause for a cause -- assumes a cause for an event where there is no evidence that one exists; it has two specific types: ‘after this, therefore because of this’ and ‘with this, therefore because of this.’
- Appeal to fear -- plays on the fears of an audience by imagining a scary future that would be of their making if some proposition were accepted
- Hasty generalization -- committed when one generalizes from a sample that is either too small or too special to be representative of a population
- Appeal to ignorance -- assumes a proposition to be true simply because there is no evidence proving that it is not
- No Scotsman -- a general claim may sometimes be made about a category of things; a challenge of the claim leads to arbitrarily redefining the criteria for membership into that category rather than arguing the challenge
- Genetic fallacy -- when an argument is either devalued or defended solely because of its history
- Guilt by association -- discrediting an argument for proposing an idea that is shared by some socially demonized individual or group
- Affirming the consequent -- a formal fallacy that takes the following form: If A then C, C; hence A
- Appeal to hypocrisy -- also known by its Latin name, tu quoque, meaning you too, the fallacy involves countering a charge with a charge, rather than addressing the issue being raised, with the intention of diverting attention away from the original argument
- Slippery slope -- the causal type attempts to discredit a proposition by arguing that its acceptance will undoubtedly lead to a sequence of events, one or more of which are undesirable
- Appeal to bandwagon -- uses the fact that a sizable number of people, or perhaps even a majority, believe in something as evidence that it must therefore be true. The bandwagon effect can be an observable behavior in social media
- Ad hominem -- attacking a person's character rather than what he or she is saying with the intention of diverting the discussion and discrediting the person's argument
- Circular reasoning -- a conclusion is either blatantly used as a premise, or more often, it is reworded to appear as though it is a different proposition when in fact it is not
- Composition and division -- inferring that a whole must have a particular attribute because its parts happen to have that attribute
We should not confuse logic with thinking, we still need to learn how to think, as logic is just a useful tool that “allows us to verify the consistency and coherence of existing chains of thought,” says Almossawi. “It is precisely for that reason that it proves an effective tool for the analysis and communication of ideas and arguments.”
While deductive reasoning links premise with conclusion through a watertight argument, we introduce complexity with inductive reasoning or bottom-up logic, which is where critical thinking becomes even more important.
[illustration of appeal to badwagon]