We like to think we make decisions based on reason, data, and logic.
But in truth, most of us .. especially in leadership .... get tripped up by the same predictable thinking traps that have been around for centuries.
Carl Sagan once compiled a list of the most common logical fallacies: the subtle errors in reasoning that make weak arguments sound convincing. Today, they’re everywhere .... in boardrooms, political debates, and social media comment threads.
Here’s a modern translation of his list, with some reflections on how each one shows up in business and leadership life.
1. Ad Hominem — Attack the person, not the argument
Instead of addressing the idea, we go after the individual.
In organisations, this often sounds like: “She’s just emotional,” or “He’s too academic to understand the real world.”
Once you start dismissing the messenger, you’ve stopped listening to the message.
2. Argument from Authority
“Because the CEO said so.”
Appeals to authority stifle curiosity. Expertise matters, but credibility is earned through evidence, not hierarchy.
3. Argument from Adverse Consequences
Believing something must be true because the alternative would be uncomfortable.
e.g. “If this risk register is wrong, the board could be exposed ,,,,,, so it must be right.”
Reality doesn’t bend to our fear of consequences.
4. Appeal to Ignorance
“You can’t prove it’s not true.”
Lack of evidence isn’t proof of anything ..... it’s just a lack of evidence.
In business, this often shows up as, “We’ve never had a data breach, so our systems must be secure.”
5. Special Pleading
The double standard that saves a failing argument: “This situation is different.”
You see this when someone insists their project shouldn’t follow the same governance rules as everyone else.
6. Begging the Question (Assuming the Answer)
Circular reasoning in disguise.
“We need this product because customers demand it.”
Do they? Or did we just decide they do?
7. Observational Selection
Cherry-picking the data that fits your story.
It’s the classic “counting the wins, forgetting the losses” problem.
8. Statistics of Small Numbers
Drawing sweeping conclusions from tiny samples.
“That customer loved it, so we’re onto a winner.”
Maybe. Or maybe it’s just one enthusiastic outlier.
9. Misunderstanding Statistics
When averages mislead.
Half of all people have “below average” performance ..... that’s how averages work. Don’t panic; understand the distribution.
10. Inconsistency
Applying logic selectively.
Demanding scientific proof for climate models but none for market forecasts is inconsistency dressed up as pragmatism.
11. Non Sequitur
“It doesn’t follow.”
“Our team is working harder than ever, so profits will rise.”
Effort and outcome aren’t automatically linked.
12. Post Hoc, Ergo Propter Hoc
Assuming causation because one thing follows another.
“After we changed the logo, sales increased.”
Correlation ≠ causation. Maybe your new rep just landed a big deal.
13. Meaningless Questions
“What happens when an irresistible brand meets an immovable market?”
Some questions just sound deep. They’re not.
14. False Dichotomy
Forcing a choice between two extremes.
“You’re either with us or against us.”
In reality, most progress happens in the messy middle.
15. Short-Term vs Long-Term
A subset of false dichotomy, but so common it deserves its own category.
Cutting training to “save” money this quarter usually costs far more next year.
16. Slippery Slope
“If we allow flexible work, no one will ever come to the office again.”
Exaggeration replaces evidence. Most slopes aren’t as slippery as they seem.
17. Confusing Correlation with Causation
“Every time we run ads, sales go up.”
Maybe ads help ...... or maybe the ads only run when sales are already trending up.
18. Straw Man
Misrepresenting an opponent’s view to make it easier to attack.
“He wants to automate everything..... he doesn’t care about people.”
No, he probably wants to eliminate waste, not humans.
19. Suppressed Evidence (Half-Truths)
Reporting the data that supports your position and ignoring the rest.
Every half-truth erodes trust a little further.
20. Weasel Words
Language that sanitises reality: “Right-sizing” instead of layoffs, “synergy capture” instead of cuts.
When leaders hide behind euphemism, they lose moral authority.
So What Can You Do About It?
Good reasoning is a discipline ... not a personality trait.
Train your team to spot the fallacies before they harden into “truth.”
Build a culture where people can ask, “What’s the evidence?” without fear.
And remember: clear thinking is not about being right , it’s about being honest with reality.
OODA Consulting — Better Systems, Smarter Thinking.