Five Days of Fallacies: Day 1, Post Hoc

Five Days of Fallacies, Day 2 here, Day 3 here, Day 4 here, Day 5 hereI am going to share some common mistakes we humans make in reasoning, in the hope that you can 1) Understand what they are 2) Recognize them when others speak 3) Recognize them when you think this way 4) Attempt to correct your thinking on old, current and future ideas.

Let’s start with one of the biggest logical fallacies: Post Hoc, Ergo Proctor Hoc.  “After this, therefore, because of this.” Affectionately known as Post Hoc, for short.

We make a mistake in seeing a causal connection between things when one action/event follows another certain action or event. This is where you get the “rain dance” from.

You did a rain dance, the next day it rained. Boom! Therefore, your dance caused the rain. Oops…Post Hoc! This is where chiropractic

outcomes originate as a viable option for people. They had a migraines, the chiro performed motions and ritualistic activity, and the mirgraine was reduced. Therefore, the chiropractic event caused the relief. Oops…Post Hoc!

Where can this get tricky? Well, I can PROVE that my rain dance made the rain. I will set a video camera up, record my rain dance, leave the camera running and then film the next day’s storm. No camera tricks! This will now circulate on the internet, someone will publish a case study on it, that case study will be cited in future publications 30 times over the year and a false foundation, built on misattributed causation, will emerge. A new area of weather control will be developed, and you, YES YOU! can come to my seminars are learn how it’s done…

You see what happened there?

That’s the Post Hoc fallacy. (Very similar to Cum Hoc, which is when two things change together, we assume causation. Example: More pumpkins were sold this month, *October, and the Stock Market increased as well. Cum Hoc Fallacy would conclude that pumpkin sales influence the stock market.)

To overcome this, you simply look to blinded good research, use the Punnet System, or go through some thinking drills. Those thinking drills could sound something like:

  • “How could this have happened any other way?” I will think of 3 other reasons for this outcome.”
  • “What factors contribute to other outcomes like this?”
  • “If I was the reason for this outcome, how could I do it better or worse? What would a better or worse outcome look like?”
  • etc…

So, think about these thought problems. “It is experience bounced off the wall of thought and thrown into the sea of reflection that ultimately returns the reward of expertise.”  

Stay tuned for more Fallacies!…

Matt D

5 thoughts on “Five Days of Fallacies: Day 1, Post Hoc

  1. Pingback: Five Days of Fallacies: Day 2, Complex Question | PTbraintrust

  2. Pingback: Five Days of Fallacies: Day 3, Irrelevant Appeals | PTbraintrust

  3. Pingback: Five Days of Fallacies: Day 4, Circular Argument | PTbraintrust

  4. Pingback: Five Days of Fallacies: Day 5, Fallacist’s Fallacy | PTbraintrust

  5. Pingback: A Year In Review: II | PTbraintrust

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