Logical Fallacies: Argument from Personal Incredulity

Introduction

In my continuing series on logical fallacies, this post is going to be about another fairly common fallacy, and one that is almost always used to negate a claim rather than support it: the Argument from Personal Incredulity.

What is the “Argument from Personal Incredulity” Fallacy?

Yet again, we have a fallacy whose name is fairly descriptive, so long as you know what “incredulity” means (“the state of being unable or unwilling to believe something”). In short, this fallacy is invoked when someone simply says, “I don’t believe that” and leaves the rebuttal there.

Example from Neil Adams, the Expanding Earth

Neil Adams is a relatively famous illustrator who is credited with – among other things – reviving Batman as a dark hero in the comic book world several decades ago. Separate from Adams’ comic book pursuits, he fancies himself an “amateur scientist” who has, among other things, completely re-written modern physics, all stemming from his disbelief in the Theory of Continental Drift (Earth’s crust being made of many plates that move around on a plastic aesthenosphere).

I have listened to three interviews that Neil Adams has given – one being on The Skeptics’ Guide to the Universe, another on Coast to Coast AM, and a third being on a podcast that had commercials so I stopped listening to it after that one episode. In all of the interviews, one of the main, founding points that Adams’ made as to why he started his re-writing of physics is that he simply doesn’t believe Earth’s crust can move around. He also states that he thinks that a planet with all the land masses on one side (as in Pangaea) would just look stupid and shouldn’t be able to happen.

That is an argument from personal incredulity — he ignores all evidence of continental drift, seafloor ages and spreading, evidence of Pangaea, and then of course the standard model of particle physics, simply by starting from the Argument from Personal Incredulity.

Example from Global Climate Change Deniers

I try to keep this blog apolitical, and I personally don’t think that global climate change should even be considered a political issue, but unfortunately these days it is. I have heard a few pieces of presumed evidence against human-caused global climate change that actually have some science behind them — this post is not meant to talk about them at all.

Rather, there are many on the anti-human-caused global climate change who start and end their arguments with, “Humans can’t possibly be responsible for global warming [sic] because Earth is too big of a system for us to have that great an effect on it.” Besides this (a) being not true, it is also (b) a rather simple argument from personal incredulity because they refuse to accept that something is possible, regardless of the evidence.

Final Thoughts

Woo-hoo! I did a Logical Fallacies post without broaching the subject of creationism. But anyway, the Argument from Personal Incredulity is another one that is incredibly easy to spot and I have seen almost everyone do it. Since becoming aware of it a year or so ago, I have tried very hard to avoid falling into the trap, though I probably have from time-to-time. It’s so easy for someone to make a claim you don’t agree with and say, “No, that’s wrong,” and leave it at that. I have even observed it when people have reviewed grants I’ve written, (start rant) stating that they don’t believe the work could be accomplished in the time stated despite me being already half-way done with it and the second half being exactly the same as the first (end rant). But now that you are aware of it, it should be simple enough to avoid using it in almost all cases.

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