What is Scepticism?

The term “sceptic” comes from the Greek word skeptikos, which means “inquiring”. Scepticism is a method of determining the truth of a claim via rational inquiry. It does not, contrary to popular belief, mean rejecting claims at face value. Scepticism has nothing to do with your conclusion, and everything to do with the method by which you reach your conclusion.

Scepticism is the best method we have for determining the truth of a claim. The scientific method is perhaps the best example of scepticism in action. This method helps prevent us from accepting false claims as true, and from accepting true claims as false.

When evaluating a claim sceptically there are essentially 2 things you should look at:

  1. Is it worth evaluating?
  2. Does it appear to be true?

Is it worth evaluating?

Not every claim is worth evaluating; some claims can be dismissed immediately. If a claim is internally inconsistent then it can be logically impossible. For example, if I claim “I am 22 years old today and I am not 22 years old today” then you can dismiss that claim right away as it’s simply logically impossible.

Claims can also be dismissed if they lack a quality known as falsifiability. For a claim to be falsifiable, it must make testable predictions that would not be true if the claim were false.  The importance of this attribute is conveyed beautifully in Carl Sagan’s essay “The Dragon In My Garage“, which the claim that an undetectable dragon is living in his garage is evaluated:

Now, what’s the difference between an invisible, incorporeal, floating dragon who spits heatless fire and no dragon at all?  If there’s no way to disprove my contention, no conceivable experiment that would count against it, what does it mean to say that my dragon exists?  Your inability to invalidate my hypothesis is not at all the same thing as proving it true.  Claims that cannot be tested, assertions immune to disproof are veridically worthless, whatever value they may have in inspiring us or in exciting our sense of wonder.  What I’m asking you to do comes down to believing, in the absence of evidence, on my say-so.

Does it appear to be true?

Once we’ve established that a claim might be correct, the next step is to check whether or not it appears to be correct. In order to do this, we need to look at what would differentiate a universe in which the claim is correct from one in which the claim is incorrect. If a claim is falsifiable, then there must be some difference between the two.

For example, I might suspect that a coin I have in my pocket is weighted such that it lands, when flipped, with the “heads” side up more commonly than it does with the “tails” side up. In order to test this, I would flip the coin.

Suppose that, after flipping the coin twice, both results were heads. Is this enough for me to conclude with any confidence that the coin is weighted? While this result is consistent with my hypothesis, it’s still reasonably likely that a fair coin would land on heads 2 times out of 2 – there’s a 25% chance of this happening to a fair coin – so I can’t really conclude yet that the coin is weighted.

This is important – and I can’t stress this enough – if you don’t have enough information you don’t have to draw a conclusion. It’s okay to say “I don’t know”. In fact, I’d go so far as to say that this is very often the correct thing to say. You should avoid making your mind up about anything until you have enough information to be reasonably confident.

Of course I can’t conclude yet that the coin is not weighted either, as there’s an even greater chance of getting this result for a coin weighted in the way in which I suspect this one to be. Before I can draw a conclusion with any reasonable amount of certainty, I’m going to need to toss the coin quite a few times.

Being able to change your mind when you receive new information is the best definition of open-minded I know. Being closed-minded is refusing to change your mind no matter what evidence you might be given. Being open-minded is re-evaluating claims when new evidence is brought to light, whether that results in a different conclusion or not.


Of course, if we were to rigorously examine every claim ever made to us, we’d never have time for anything else. Especially in our daily lives, we need to be able to take some shortcuts, and we don’t always need to demand certainty to the same degree.

Things like trust are often good shortcuts – if we trust someone then we might take their word for something – although for stranger or more important claims it’s still important to be sceptical. Contested claims, also, should generally be examined more sceptically.

When evaluating more important claims like “vaccines cause autism” or “my medicine can cure your cancer”, it is of utmost importance that we examine these claims rigorously. This is what the scientific method, in particular, is great at doing. By incorporating concepts such as controlling and blinding into a scientific test, we can evaluate a claim very rigorously.

There’s one more criteria that should be taken into account for some claims. If a claim is both internally consistent and falsifiable, but disagrees with what we currently think we know, then we need to be much more careful about whether or not we accept it, as accepting such a claim as true also means rejecting a previously accepted claim as false. How consistent a hypothesis is with what we currently know is generally known as the scientific plausibility of a claim.

In order for one idea to supplant another idea of which we are very confident, such as a scientific theory, it needs to make better predictions than the previous idea. For example, Einstein’s theory of general relativity superseded Newtonian gravity after it was shown that the new theory better predicted the orbit of Mercury while remaining consistent with other correct predictions of Newtonian gravity. When this sort of thing happens, the new idea is practically always a variation of the old idea.

Honest Universe

Scepticism is the best tool we have when it comes to forming accurate conclusions about the universe in which we live. It works because, even in its marvellous complexity, our universe is an honest universe.

Napier Church Replaces One Stupid Message With Another

Recently, a billboard was put up by the Napier Equippers Church in New Zealand carrying the message “Jesus heals cancer“, later accompanied by a tally of 6 representing those whom the church believed to have had their cancer healed by Jesus. 9 complaints were made to the New Zealand Advertising Standards Authority about the billboard, which prompted an investigation.

The executive pastor of the church, Earl Joe, has said:
“We’ve seen, just recently, six people healed from cancer”
“Can Jesus heal cancer? Yes, we believe he can.”
“We’ve actually seen healings in the church, yes cancer, absolutely.”
He also said the church’s members believed that Jesus could “heal cancer, or the common cold, or the headache”.

Since the start of the investigation, the church has replaced the billboard with a very similar one. The new message reads  “Jesus heals every sickness and every disease – Matthew 4:23”

The billboard as of 29th February 2012 (source)

I absolutely loathe seeing any promotion of the dangerously wrong idea that so-called “faith healing” can actually heal, especially in the case of terminal illnesses such as cancer. Faith healing simply doesn’t work, and promoting it in any way is irresponsible. Whoever’s idea this billboard was should be ashamed of themselves.

Even though there were complaints about this billboard, I think it’s a decent example of how criticising religion has become a social taboo. Jody Condin, who spoke to the Hawkes Bay Today about her outrage about the billboard, seemed to feel the need to defend her actions:

“If the church and its members truly believe that Jesus heals cancer, then fine, that’s their view and each to their own”

Imagine if a non-religious organisation had put up a billboard claiming to know that they have a treatment that can heal cancer, but in reality the treatment had no such effect, and it was trivial to discover this.

How does the fact that it would be a non-religious claim make that any more of an abomination than the religious claim put forth by the billboard? How much worse is it to claim that the same treatment can “heal any sickness or disease”? People should not need to feel guilty when speaking out about dangerous lies such as this.

In response to the first message Sue Chetwin, the Consumer NZ chief executive, said “Do we want regulations for this sort of thing? A sensible person would probably ignore it”.

Again, perhaps extending this response to an equivalent claim made by a non-religious organisation will demonstrate how absurd it is, and make the answer seem more obvious:

Yes, claims in advertising about what will and what will not heal sickness and disease, especially potentially terminal illnesses such as cancer, should be regulated. I would have hoped that would be obvious…

On the plus side, I now have a new reference passage that I can use to demonstrate some of the blatant falsehoods in the bible – Matthew 4:23.

(found via Friendly Atheist)