Post Hoc Reasoning in Arguments

Definition of Post Hoc Reasoning

Post hoc reasoning is a type of incorrect thinking that happens when someone believes that if one event happens after another, the first event must be the cause of the second one. Like thinking rain is caused by washing your car because every time you wash your car, it rains later. This is a sneaky mistake in logic because it seems to make sense but can lead you to the wrong conclusion.

The full Latin term, “post hoc ergo propter hoc,” helps us understand this error better. It means “after this, therefore because of this.” This kind of reasoning trips us up because humans like to find simple patterns. So, if “A” comes before “B,” it’s tempting to say “A” made “B” happen, even though that might not be true. It’s like blaming a soccer team’s loss on the new shoes someone wore that day, even if the loss had nothing to do with them.

How to Guide – Spotting Post Hoc Reasoning

  • Look at the sequence: Did one event really cause the other just because it came first?
  • Ask for evidence: Is there real proof the first thing caused the second?
  • Search for alternatives: Could there be another reason why the second thing happened?
  • Think critically: Just because two things happen together, doesn’t mean one caused the other.

Types of Post Hoc Reasoning

While post hoc reasoning is already a specific kind of logical error, it shows up in various contexts, making it look different in different situations. These scenarios demonstrate how this reasoning can mistakenly be used for other errors that seem related, such as thinking something is lucky or unlucky just because of what followed.

Examples of Post Hoc Reasoning In Arguments

  • If a soccer team wins a match after their coach buys them new uniforms, they might think the uniforms brought them good luck and caused the win. This is an example of post hoc reasoning because the team is connecting the win to the new uniforms without considering their skills or the other team’s performance.
  • Imagine you eat a cookie and then you get a headache. You might think the cookie caused the headache, but it could just be a coincidence or maybe you were already starting to get a headache for another reason. This shows post hoc reasoning as you’re linking the cookie to your headache without enough evidence.
  • When someone takes vitamin C and their cold gets better, they might believe the vitamin C cured them. This is post hoc reasoning because colds often improve over time, and without clear evidence, you can’t be sure the vitamin C was the real cure.

Why is it Important?

Understanding post hoc reasoning stops us from making quick judgments without the facts. If we believe something caused something else just because it came first, we might make decisions based on false beliefs. This kind of thinking could lead to incorrect medical choices, wasteful spending on products that don’t work, or supporting the wrong causes. By learning to look for strong evidence and considering other possibilities, we protect ourselves from these mistakes and develop a habit of thinking properly about cause and effect in our everyday lives.


The roots of post hoc reasoning dig deep into our history of trying to make sense of the world around us. Our brains naturally look for patterns and connections, which is why this error in logic has stuck around for such a long time. Philosophers have long explored this concept when discussing the right ways to understand cause and effect.


While post hoc reasoning itself isn’t a hot-button issue, where people get tripped up is in how much evidence is needed to support a cause-and-effect relationship. Some argue that just because an event doesn’t always lead to the same outcome, it doesn’t mean it never can. But without clear evidence, it’s just assumption, not conclusion.

Understanding Post Hoc Reasoning

  • Correlation does not imply causation: Just because two things occur together doesn’t mean one is the result of the other.
  • Common in superstitions: Superstitions, like knocking on wood for good luck, often come from seeing a pattern and wrongly thinking it’s a cause.
  • Scientists try to avoid it: Reliable scientific studies and experiments are designed specifically to prevent this type of error and find out true causes.

Remember, when someone suggests that A caused B simply because A came first, consider other possibilities and ask for proof. This way of thinking helps you navigate the world more wisely, whether you’re making a big life decision or just figuring out what to have for lunch.

Related Topics with Explanations

Post hoc reasoning connects to other logical fallacies and important concepts that can help us sharpen our critical thinking skills. Here’s a look:

  • Correlation vs. Causation: Understanding that events occurring together don’t prove one caused the other.
  • Confirmation Bias: The tendency to only accept information that supports what you already believe, which can make post hoc reasoning more convincing.
  • Critical Thinking: The skill of evaluating arguments and evidence with an open mind, which helps to avoid falling into the post hoc reasoning trap.


Post hoc reasoning is a common mistake, but knowing about it can help us avoid jumping to false conclusions. It challenges us to ask questions and look for real causes instead of simply linking events by their order. By being aware of this fallacy and practicing good thinking habits, we can make smarter decisions and better understand the world around us—and that’s a valuable skill for anyone, at any age.