Updated: Jan 18

What is a “philosophical razor”?

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 the 9:

  • Occam's razor: The simplest explanation is usuallybut not always – the correct one

  • Sagan standard: Extraordinary claims require extraordinary evidence

  • Hitchen's razor: What can be asserted without evidence can be dismissed without evidence

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

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

  • Popper's falsifiability principle: For a theory to be scientific, 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

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

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

Occam’s razor

“Entities should not be multiplied without necessity.” – Occam’s razor

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 usuallybut not always – the correct one.

For example, which is more likely to be true: A woman drowned her five children in the bathtub because: a) God or Satan told her too b) She is insane and is suffering from psychosis and schizophrenia

A UFO in the sky is: a) Aliens from another galaxy b) A type of aircraft or drone you haven’t seen before, maybe one that the air force is flight testing Paleontologists have discovered dinosaur bones in the earth because: a) Dinosaurs once lived on the earth b) God or Satan put the dinosaur bones in the earth to test the faith of Christians Yep, the simplest explanation is usuallybut not always – the correct one, therefore always start by asking:

“What is the simplest and most likely explanation?”

Instead of starting with complex or far-fetched theories which are less likely. That doesn’t mean that you have to eliminate complex or far-fetched theories completely, it just means you should start with the simplest and most likely ones. If someone has a headache, it could be brain cancer, but let’s start off by assuming it’s just a headache. Note: Occam’s razor doesn’t allow for the exclusion of data or evidence, so if the simplest explanation doesn’t account for all the data and evidence, then it’s not the best explanation.

“Everything should be made as simple as possible, but not simpler.” – Albert Einstein

Occam’s duct tape

The opposite of Occam’s razor is Occam’s duct tape which is when someone approaches a problem with a ridiculously large number of assumptions. Sagan standard

Sagan Standard

“Extraordinary claims require extraordinary evidence” – Carl Sagan If someone claims that their name is Michael, or that their dogs 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.

It’s not good enough for new-age/religious/spiritual teachers and their followers to simply assert that these things are true, or to imply that their guru or teacher possesses these supernatural abilities, extraordinary claims like these must be backed up by extraordinary evidence. Unfortunately new-age/religious/spiritual teachers and their followers frequently make extraordinary claims like these, and have them believed by millions of people without the slightest bit of evidence or proof. However, if most people were critical thinkers that demanded evidence for their beliefs, this wouldn’t happen. The James Randi foundation had a $1 Million Dollar Paranormal Challenge from 1964-2015 that offered the money to anyone who could demonstrate any occult, paranormal or supernatural ability of any kind, under agreed-upon scientific testing criteria. Over a thousand people applied to take it, but none were successful.

Hitchen’s razor

“What can be asserted without evidence can also be dismissed without evidence.” – Christopher Hitchens

Hitchen’s razor ties in nicely with the Sagan standard. 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.

For example: If I claim to be able to contact the dead, predict the future, read minds etc. it’s not up to you to prove that I can’t – it’s up to me to prove that I can. I’m the one making the claim – therefore it’s up to me to prove it. However, if someone is making extraordinary claims that demand evidence, but is unable or unwilling to provide that evidence, you can dismiss those claims without evidence. There is simply no need to waste time arguing against unsubstantiated claims. Hitchens razor will save you a lot of time, because most people don’t have any evidence to back up their assertions.

Hume’s razor

“If the cause, assigned for any effect, be not sufficient to produce it, we must either reject that cause, or add to it such qualities as will give it a just proportion to the effect.” – David Hume

Hume’s razor states that 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. If a proposed cause isn’t sufficiently able to produce the observed effect, we must either eliminate the cause from consideration, and come up with another hypothesis, or show what needs to be added to the cause to create the effect.

Duck test

“If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck.” – Duck test 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. I know that in the world of deep fakes, fake news, fake people, scams etc. it might be considered unwise or even dangerous to take appearances for reality, however, although appearances can be deceiving, there is generally no need to deny reality or what’s right in front of your eyes. Generally speaking, what you see is what you get. If someone or something seems a certain way, they probably are that way.

Popper’s falsifiability principle

“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. Hypothesis that are impossible to disprove, refute or test are unfalsifiable, and are therefore not scientific e.g. “Aliens that exist in other dimensions outside of our reality secretly control our minds and everything we think, say and do.”

Falsification is a good rule of thumb to apply when you’re presented with any claim or theory. Ask yourself: How can I test this theory? What would disprove it? What would refute it? e.g. a single black swan would falsify the theory that “all swans are white”.

However, if someone makes a claim that is unfalsifiable and can’t be tested, proven or disproven, verified or falsified e.g. an extraordinary new-age/religious/spiritual claim or conspiracy theory about aliens in other dimensions, it’s probably best to dismiss it instead of speculating and taking it seriously.

Karl Popper’s rules for falsification

The criteria for when a theory should be considered scientific, and for how to distinguish between science and pseudoscience: 1. It is easy to obtain confirmations, or verifications, for nearly every theory – if we look for confirmations 2. Confirmations should count only if they are the result of risky predictions; that is to say, if, unenlightened by the theory in question, we should have expected an event which was incompatible with the theory–an event which would have refuted the theory 3. Every ‘good’ scientific theory is a prohibition: it forbids certain things to happen. The more a theory forbids, the better it is 4. A theory which is not refutable by any conceivable event is nonscientific. Irrefutability is not a virtue of a theory (as people often think) but a vice 5. Every genuine test of a theory is an attempt to falsify it, or to refute it. Testability is falsifiability; but there are degrees of testability: some theories are more testable, more exposed to refutation, than others; they take, as it were, greater risks 6. Confirming evidence should not count except when it is the result of a genuine test of the theory; and this means that it can be presented as a serious but unsuccessful attempt to falsify the theory 7. Some genuinely testable theories, when found to be false, are still upheld by their admirers–for example by introducing ad hoc some auxiliary assumption, or by re-interpreting the theory ad hoc in such a way that it escapes refutation. Such a procedure is always possible, but it rescues the theory from refutation only at the price of destroying, or at least lowering, its scientific status One can sum up all this by saying that the criterion of the scientific status of a theory is its falsifiability, or refutability, or testability.

Newton’s flaming laser sword

“That which cannot be settled by experiment is not worth debating” — Mike Alder

Australian mathematician Mike Alder coined the term “Newton’s flaming laser sword” in this article for Philosophy Now, in which he advocates only focussing on problems which can be settled by a combination of experimentation and reasoning, and not just argumentation. Mike came to this conclusion when he was ten years old, after a school teacher asked him the irresistible force paradox:

“What would happen if an irresistible force acted on an immovable object?” Mike’s first response was that if the force was irresistible, then the object must move. “Ah,” said the teacher, “but the object is immovable.” He then continued to think about the problem for three days, and eventually concluded that reason alone did not solve the problem, we couldn’t just speculate on what would happen, we needed to perform an experiment to settle the matter, we needed to test out the irresistible force on the immovable object to see what would happen. Either the object would move or it wouldn’t, which would tell us whether the immovable object was really immovable, or the irresistible force was really resistible. Mike stills holds this view today, that pure reasoning alone is insufficient to solve many important problems, as do the vast majority of scientists:

“The orthodox position of scientists: truth about how the universe works cannot generally be arrived at by pure reason. The only thing reason can do is to allow us to deduce some truth from other truths. And since we haven’t got many truths to start out from, only provisional hypotheses and a necessarily finite set of observations, we cannot arrive at secure beliefs by thought alone. Most scientists take the view that their professional life consists of finite observations, universal general hypotheses from which deductions can be made, and that it is essential to test the deductions by further observations because even though the deductions are performed by strict logic (mathematics usually), there is no guarantee of their correctness. The idea that one can arrive at reliable truths by pure reason is simply obsolete. Plato believed it, but Plato was wrong.” – Mike Adler

In a nutshell: Newton’s flaming laser sword says that 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. Which horse is faster? Race them. How many teeth does your dog have? Count them. Which MMA fighter is better? Make them fight. Do heavy objects fall faster than light objects? Perform the experiment Reason alone isn’t enough. Engaging in untestable speculation is a waste of time. Obviously Newton’s flaming laser sword excludes a lot of things (anthropology, history, politics, ethics etc.) and should therefore be used very cautiously. Not everything is observable, measurable, repeatable, testable etc. so as to be fit for the scientific method. “While the Newtonian insistence on ensuring that any statement is testable by observation (or has logical consequences which are so testable) undoubtedly cuts out the crap, it also seems to cut out almost everything else as well. Newton’s Laser Sword should therefore be used very cautiously. On the other hand, when used appropriately, it transforms philosophy into something where problems can be solved, and definite and often surprising conclusions drawn.” – Mike Adler

Grice’s razor

“Conversational implications are to be preferred over semantic context for linguistic explanations.” — Paul Grice Grice’s razor says that when in conversation, it’s best to address what the speaker actually meant, instead of addressing the literal meaning of what they actually said.

This is a good rule of thumb because most people are poor communicators and struggle to find just the right words and examples to express themselves. Even despite our best efforts the words don’t always come out right, or the way we intended them to. Sometimes people are also trying to express an idea they don’t yet know how to articulate.

So don’t take everything someone says literally and get into silly arguments over semantics, and the most minute, insign