Posted by Life Lessons
In philosophy, a razor is a principle or a rule of thumb, that allows for the elimination (the “shaving off”) of unlikely explanations for a phenomenon.


A philosophical razor is not an unbreakable law or rule, it is not always right 100% of the time, but it is right more often than not, and is therefore a useful mental shortcut that allows you to make decisions and solve problems quicker and easier.

Here are nine philosophical razors you need to know:


Occam’s razor: The simplest explanation is usually – but not always – the correct one.

Occam’s razor is a problem solving principle that states that when you’re presented with multiple competing hypothesis for a phenomenon, or explanations for an event, you should start by selecting the simplest and most likely one, the one that makes the fewest assumptions.

Why? Because the more assumptions there are, the more possibilities there are for error, and the simplest explanation is usually – but not always – the correct one.


Sagan standard: Extraordinary claims require extraordinary evidence.

If someone claims that their name is Michael, or that their dog’s name is Charlie, that’s not an extraordinary claim. It’s reasonable to simply take them at their word.

However, if someone claims that they, or their guru/religious/spiritual teacher, can contact the dead, see the future, read minds, cure or heal any disease or sickness including AIDS or cancer, talk directly with God (and have God talk back unambiguously), perform miracles, or that they have supernatural powers of any kind, than these are extraordinary claims, and they must be backed up by extraordinary evidence such as a live demonstration to prove it.


Hitchens razor: What can be asserted without evidence can be dismissed without evidence

If someone is going to assert something without evidence, especially an extraordinary claim that demands evidence, you can dismiss it without evidence.

This is because the burden of proof is always on the one making the claim, not the other way around.


Hume’s razor: Causes must be sufficiently able to produce the effect assigned to them

 e.g. a slight gust of wind isn’t enough to cause a Boeing 747 to crash, and a fallen power line isn’t enough to cause a nationwide blackout.





Duck test: If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck.

The duck test is about abductive reasoning and drawing the most likely conclusion given the evidence, instead of denying the obvious. It’s sometimes used to counter arguments that someone or something isn’t what they appear to be.


Popper’s falsifiability principle: For a theory to be considered scientific, it must be possible to disprove or refute it.

“It is easy to obtain confirmations or verifications for nearly every theory – if we look for confirmations. Every genuine test of a theory is an attempt to falsify it, or refute it.” – Karl Popper

Karl Popper’s Falsifiability Principle is that for a statement, hypothesis, or theory to be considered scientific, it must be falsifiable, that is, it must be possible to disprove or refute it.



Newton’s flaming laser sword: If something cannot be settled by experiment, it is not worth debating.

You should generally only focus on problems that can be solved by a combination of experimentation and reasoning, and not just argumentation, and if it’s possible to perform an experiment to settle a matter you should. This will save you from wasting a lot of time on (currently) unanswerable questions and allow you to make progress faster.


Grice’s razor: Address what the speaker actually meant, instead of addressing the literal meaning of what they actually said.

“Conversational implications are to be preferred over semantic context for linguistic explanations.” — Paul Grice




Hanlon’s razor: Never attribute to malice that which can be adequately explained by incompetence or stupidity.

If someone acts in a way that affects you negatively, it’s not necessarily because they have bad intentions towards you, or mean you harm.