Logic Miniseries: Part 3 – Informal Logic and Fallacies of Ambiguity

Time to make good on my promise of this section being the more interesting part of the miniseries.  Now that we know how the laws of logic work, coupled with some simple logistical vocabulary and methodology on how logic flows, we can now dive into the wonderful world of informal logic.   Otherwise called ordinary/everyday logic, informal logic seeks to develop, assess, and analyze arguments that happen in daily discourse.1

ajedrez-640385_640Have you ever wondered why, when conversing with an opponent, something just doesn’t sound right in their reasoning and just couldn’t put your finger on it?  In other words, what to call it?  I hope you said, “Yes.”  That’s great!  Me too!  In ordinary language discourse, we can commit subtle (and not so subtle) errors in reasoning, called fallacies.  There are three main categories of fallacies in informal logic: ambiguity, presumption, and relevance.  Many such fallacies exist.  However, I’ll only be addressing the ones most commonly used in apologetic dialogue.  Due to the complexity of each, this post will address the fallacies of ambiguity, the next post – presumption, and following that – relevance.

Fallacies of ambiguity are committed when a word, phrase, or sentence is one that has two or more distinct meanings.  There are six types of fallacies which are ambiguous: equivocation, amphiboly, composition, reification, accent, and division.2  In apologetic conversation, the fallacies most commonly committed are equivocation and reification.  The fallacy of equivocation is committed when the meaning of a word is shifted in the course of argument.  For example, “That baby is very messy when she eats.  My mom calls my dad, ‘baby’; therefore, my dad must be a messy eater.”  In the first sentence, baby is being used to describe a young child, while the second is a figure of speech used as a term of endearment (although the father could still be a messy eater, ha!).

A very common example of equivocation in apologetics is, “Evolution is true because wesilhouettes-776666_640 see evolution happening every day.” The first use of the word ‘evolution’ is referring to the theoretical concept of humans evolving from a common ancestor.  The second is referring to a general change.  Just because there is a general change within a species does not mean we evolved from a common ancestor.  In other words, changing from one species to another.  Another common example is, “The science of evolution is quite clear on our origins.  Science has helped us develop technology and all sorts of other tools we use on a daily basis, so there’s no denying it.”  The first use of the word ‘science’ refers to origin science which is supposed to help us understand past events given present evidence.  However, the reliability of such is quite questionable since many findings cannot be tested, or recreated (e.g. The Big Bang Theory).  The latter refers to operational science, or repeatable observations and experiments in the present.  It shifts meanings from one phrase to the next, thus committing the fallacy of equivocation.

Have you ever heard someone say, “You shouldn’t try to fool Mother Nature?”  If you have, great!  You’ve then heard an example of reification; giving something concrete and often personal attributes to an abstraction.  Nature cannot be fooled; it is a concept.  Nature does not have a mind!  Another common example is, “Evolution is true because science says so.”  Science says no such thing.  Again, it’s a concept; a tool we use to measure and predict how the universe works.  Humans are behind the interpretation of science.  We are doing the ‘saying’, not science.  Okay, one more example, “The evidence speaks for itself.”  Does evidence speak?  No, of course not.  It’s we who do the speaking upon our interpretation of such evidence.3

See, I told you we’d have a bit more fun.  I hope that was the case.

Onward we move!  My next post will highlight fallacies of presumption, for which I’ll be using examples from social media comments (which are always a blast!).


1  http://plato.stanford.edu/entries/logic-informal/

2  Kemerling, G. (2011).  Fallacies of Ambiguity.  Retrieved from http://www.philosophypages.com/lg/e06c.htm

3  Lisle, J. 2009. The Ultimate Proof of Creation: Resolving the Origins Debate. Master Books: Green Forest, AR.

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