When looking at this question, the phrase "doubting Thomas" popped into my head as a potential answer. That in turn led me to question the origin of the phrase, which I discovered comes from the Apostle Thomas being skeptical of Christ's resurrection.

After learning that the phrase "doubting Thomas" has a religious origin, I'm curious...Does a "colorful*" expression that is secular in nature exist to describe a skeptical person, and if so, what is it?

Obligatory frame sentence:

That guy never believes anything without proof; he's a(n) _____________.

*By "colorful," I mean a bit more inventive/expressive than simply "skeptic," "doubter," etc.

Edit to address smci's comment: I prefer an existing and reasonably common expression; however, I will accept an uncommon or newly created expression that would be widely understood if there seems to be a consensus that a common one does not exist.

Edit to address MετάEd's comment: To further clarify and keep the question within the appropriate scope, I am not looking to compile a list of similar expressions. I'd like to identify the most common, secular expression that closely matches "doubting Thomas" in meaning and usage.

***To preserve the validity of answers that suggested coining new expressions, note that several users have asserted the lack of an expression that meets the criteria I've laid out.

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    When you say 'exist', the answer is there aren't any (in common use) more colorful than skeptic. If you're asking us to make one up, please rephrase the question accordingly.
    – smci
    Commented Aug 1, 2016 at 8:00
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    Just a small bit of trivia on "doubting Thomas": According to the dictionary information linked to in Josh61's answer, the first known use was 1883. (I expected it to have been in use for longer.)
    – pyobum
    Commented Aug 1, 2016 at 8:29
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    If you wanted to weed out not just direct references to a deity but all words or phrases which could be traced back to a religious origin, you would pretty soon end up with almost no words left in the language.
    – vsz
    Commented Aug 1, 2016 at 11:59
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    Do you want to retain the negative connotation of "Doubting Thomas"?
    – smithkm
    Commented Aug 2, 2016 at 8:01
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    Do you also object to words like "martial" and "venereal" that were derived from the names of Roman gods? Just because a word has its origins in religion doesn't mean that the word itself can't be used in a secular context.
    – Nicole
    Commented Aug 3, 2016 at 16:24

12 Answers 12


That guy never believes anything without proof, he’s a real show-me guy.

Google finds a lot of examples of this being used in, what seems to me, the sense you are looking for and it is also easy to understand from context even if one hasn’t encountered it before.

I am very much a “show me” guy and no amount of claims over the phone is going to convince me.

I'm a "science" kind of guy, a "show-me" guy, someone who tends to need some proof about claims I find questionable.

He was very much a "show me" guy. When he heard that magnesium would burn underwater he took a five-gallon coffee can to work and filled it with magnesium chips from the shop floor. He put the can in the driveway at home and filled it with water,

My only reservation with this is that people do tend to put the phrase in inverted commas when they write it, which seems to set it apart as though they don't quite feel it is 'proper' language.

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    I would say that the phrase is placed in quotation marks when used to indicate that it is metaphorically being spoken, not because it is "improper". i.e. the meaning of the phrase "a real 'show-me' guy" is "a guy who says 'show me' when told about something unfamiliar".
    – recognizer
    Commented Aug 1, 2016 at 22:39
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    FWIW I've never heard this. In what dialect of English is it best understood? Commented Aug 2, 2016 at 11:18
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    @LightnessRacesinOrbit Well, I have heard it on occasion here in Scotland, but also encountered it in general interest reading online and US based fiction. Most of the search hits look to be from the US, and Quaternion's answer suggests that Missouri may lay claim to it, but I have no particular knowledge on that score. And as I say, it pretty much explains itself in context and may well have arisen spontaneously in more than one place..
    – Spagirl
    Commented Aug 2, 2016 at 12:56
  • Supporting definition for "show-me": dictionary.com/browse/show-me
    – pyobum
    Commented Aug 3, 2016 at 0:51
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    @Spagirl I think the "Show Me" state (Missouri, as you noted) is quite possibly the only place that is in any significant use here. I have never heard usage like that in California, Texas, Idaho, Colorado, Florida, Massachusetts, or Rhode Island.
    – Doktor J
    Commented Aug 3, 2016 at 6:02

As an alternative view to your statement I'd say that the expression doubting Thomas has been secularised in the English language from the start since there is no mentioning, as in other languages, of the "Saint" Thomas.

In French: Saint Thomas : "Je suis comme Saint Thomas, je ne crois que ce que je vois"

In Italian: San Tommaso. "Fare come San Tommaso"

In Spanish: Santo Tomás: "Ver para creer, como Santo Tomás."


What about

"That guy never believes anything without proof; he's from Missouri/a Missourian".

Someone "from Missouri" is someone who always needs proof, who always doubts. I think this option has the exact meaning you desire, and it also seems to satisfy the criterion of being "colourful".

(McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.)

  • And it's well established and recognized, at least in the United States, where Missouri is nicknamed "The Show Me State". It's definitely secular, and you can find (one version of) it's origin/popularization here.

If someone doubts something, they are sceptical and therefore a sceptic

(Skeptical/skeptic in US English)

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    OP stated in the question, By "colorful," I mean a bit more inventive/expressive than simply "skeptic," "doubter," etc. Commented Aug 2, 2016 at 16:00

I couldn't find anything from researching it (well not anything colourful).

So I decided to invent a term... only to find it has actually been used elsewhere. Makes me feel pretty noble ;)

Anyway this is my offering...

A "Septic Sceptic"

The connotations being a person that so doubts everything they make their life a misery of indecision and unbelief, and possibally also infect those around them with this contaminated view point.


1: of, relating to, or causing putrefaction
Merriam Webster

I couldn't find a defintion of the term in any dictionaries but I have found some examples of the term being used: -

"Aunt Maud's perceptions were somehow septic. A septic sceptic."

Blue Voyage: A Novel, Conrad Aiken, 1927 (ref)

and here is another more recent example: -

"Deborah laughed. 'You're impossible. Even you admitted that of all the psychics you investigated over the years, Oliver Sangster is the only one who cast doubt into your suspicious mind... So, how did he predict the bus crash? Come on Septic Sceptic. Explain.' "

Whispers of the Dead, Anthony Hulse, 2014 (ref)

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    +1 for a lovely (lovelily?!) alliterative coining! I think you've misread your Tamil dictionary, though—that mention is in a list of English words commonly confused. It gives septic ~ sceptic as a pair of easily confused words and then explains what each of them means. It doesn't say anything about septic sceptics as a collocation. Commented Aug 1, 2016 at 6:38
  • haha oh ok, thank you - for pointing that out. I'll revise the answer, well spotted! (it did find it peculiar that was the only dictionary I could find an answer in) and thanks for the feedback too, appreciated.
    – Gary
    Commented Aug 1, 2016 at 6:52
  • +1 Sometimes you just have to invent it yourself. (even if it's a re-invention)
    – TecBrat
    Commented Aug 2, 2016 at 18:59

Descartes is the modern philosopher who is most associated with doubt, quoting him:

The first [principle] was never to accept anything for true which I did not clearly know to be such; that is to say, carefully to avoid precipitancy and prejudice, and to comprise nothing more in my judgment than what was presented to my mind so clearly and distinctly as to exclude all ground of doubt.

Thus, the word Cartesian can qualify someone who doubts by nature and requires a proof of any assertion — although compared to Thomas, he requires a logical proof and distrusts his senses more than his brains. Depending on the context and what you want to achieve, you might even coin a doubting Descartes, which will insist on secularism even more thanks to its parallelism to doubting Thomas.

A British alternative to Descartes, as you point yourself, is Hume, and indeed in Oxford dictionaries the adjective Humean is listed with the relevant example sentence:

Relating to or characteristic of the Scottish philosopher, economist, and historian David Hume or his ideas:

a critic of Humean scepticism

  • Poking around online a bit, I found that "Cartesian doubt" and "Cartesian skepticism" are common phrases, so there might be enough there to make a connection with "Cartesian Carl." Eh? Anybody? Also, I found the Scottish philosopher David Hume, "known especially for his philosophical empiricism and skepticism." "Doubting... David"? (I think I'm getting too far afield.) Anyway, +1.
    – pyobum
    Commented Aug 1, 2016 at 8:49
  • Not sure where Carl comes from...? Prompting Descartes comes to mind because there is a well established adjective Cartesian, although in English language this is not directly associated with doubt method (in French, it is used more in this sense, a Cartesian person will not accept nonscientific belief). Humean can be a British equivalent indeed. Doubting David however would probably make your reader think you mixed up Goliath and the resurrected Christ...
    – Joce
    Commented Aug 1, 2016 at 9:18
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    I do have a reasonably strong maths/computing background, and Descartes is responsible for so much that "Cartesian" on its own doesn't imply to me "Cartesian doubt" in particular. It could as well mean other things (co-ordinates and their use in geometry, dualism), so "Cartesian" alone just isn't enough regardless of how well you know him. If the only thing you know about Descartes is "cogito ergo sum" and the methodology that lead to him (needing to) assert that, then the implication will work. Commented Aug 1, 2016 at 12:25
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    @SteveJessop: yes, but applied to a person, you wouldn't infer that he objects living in a world described by spherical coordinates, would you? ;)
    – Joce
    Commented Aug 1, 2016 at 12:27
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    @JonStory: yes, I agree it is not common, as I've already said above. But the OP is asking for colourful phrases and it seems there are no common ones, so at best we can offer less common one that make sense. Doubting Descartes (or doubting Hume, which lacks the alliteration) can have a double function of evoking something well-known (doubting + proper noun will of course bring St Thomas in mind) and stress that the author does not want to use religious reference. Even if the reader is not well aware of Descartes, he'll get the intention—and can learn something on the occasion.
    – Joce
    Commented Aug 1, 2016 at 13:29

"That guy never believes anything without proof; he's an empiricist," one with "The view that experience, especially of the senses, is the only source of knowledge."

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    That's accurate meaning-wise, but as I mentioned, I'm looking for something less "dry."
    – pyobum
    Commented Aug 1, 2016 at 5:17
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    Where I grew up, such a colorful descriptor of someone could well result in a knuckle sandwich. ;)
    – KWinker
    Commented Aug 1, 2016 at 7:50
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    @pyobum I'm not so sure it is that accurate meaning-wise. I feel like "That guy never believes any proof; he's an empiricist" is at least as valid a usage. (In science, an empricist is the opposite of a theorist.) In any case, empiricism doesn't have to coincide with skepticism.
    – Kimball
    Commented Aug 1, 2016 at 11:37
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    @Kimball: in the context of Saint Thomas, though, "proof" here means proof by presenting physical evidence, not proof by 27 pages of abstruse mathematics whose applicability is not absolutely certain ;-) He said "Unless I see the nail marks in his hands and put my finger where the nails were, and put my hand into his side, I will not believe." (NIV John 20:25), not "Unless your theoretical model predicts it, I will not believe". Commented Aug 1, 2016 at 12:36
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    @SteveJessop Yes, and I know proof means something different in the empirical model versus the theoretical model, but I'm still skeptical of this usage of "empiricist." I think at least the common usage of empiricist doesn't imply one is slow to believe. (And my recollection is that Thomas already had empirical (visual, aural) evidence before doubting---he needed overwhelming evidence to be convinced.)
    – Kimball
    Commented Aug 1, 2016 at 12:54

Blaise Pascal names sceptics Pyrrhonists in his Pensées, which I find a rather colorful solution, albeit probably with a stronger meaning than simply "not believing what one has not seen": indeed pyrrhonists seem to doubt even of what they do see.

  • A little more detail would be nice. Commented Aug 4, 2016 at 6:16

I'm going to make the case for Doubting Thomas, on the grounds that its religions origin is irrelevant (to pretty much everyone). Etymology is not meaning.

This type of word/phrase is an allusion. Allusions are popular in English, and the Bible, as a source of many stories that are widely known, is a popular choice for allusion. Another choice is Shakespeare. In a few decades, maybe Harry Potter will be people's choice of allusion, and you might hear a teacher say

You're a real Hermione Granger

to a student who's memorized every school textbook.

Here is a list of some commonly-used allusions. Note that some of them are religious in origin, but the source religion is not Christianity (example: erotic is from the god of love Eros).

Doubting Thomas is a character in a story. Whether the story is true or not doesn't matter as much as people understanding your allusion. This is different from, say, trying to avoid religious sentiment when you don't intend it. For example, some people feel compelled to say something when another person sneezes, but they don't want to say "Bless you". In that case, a non-prayer-related interjection is required, such as "gesundheit". In this case, Doubting Thomas doesn't convey any notions of prayer, or belief, or anything. It does convey the notion that Thomas was wrong to doubt, which may be something to avoid.

It should also be noted that lots of common words and expressions are religious in origin, such as "good-bye", "damn", "hellish", etc. I think most atheists wouldn't blink at saying something like "Damn, today's shift at work was hellish. I can't wait to say good-bye to that place."


William Safire's "Nattering nabobs of negativism" could be applied.

  • Thx for the downvote. I expected it. It's still a perfectly good answer, if not persnickety enough for some. Commented Aug 1, 2016 at 22:27
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    +1 for this tidbit -- I should have known Spiro Agnew could not have thought that up all by himself.
    – ab2
    Commented Aug 2, 2016 at 0:55
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    Please explain your answer in full. Why could it be applied? Commented Aug 2, 2016 at 20:29
  • I didn't downvote, but I don't see how "nattering nabobs of negativism" relates to skeptics.
    – pyobum
    Commented Aug 3, 2016 at 0:29
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    A skeptic is not necessarily a negative person; they just desire more proof/concrete evidence. This would be a poor fit to the OP's answer. I didn't downvote, but thought about it for a bit ;)
    – Doktor J
    Commented Aug 3, 2016 at 6:05


Empiricism is a theory that states that knowledge comes only or primarily from sensory experience.

Thomas did not believe the other apostles because he had not seen it with his own eyes, thus he was an empiricist.

Or, as in your example:

That guy never believes anything without proof; he's an empiricist.

  • Looks like pretty much the same answer as KWinker's answer.
    – J.R.
    Commented Aug 2, 2016 at 21:39
  • @jr Opps. I didn't notice that someone had already suggested it. Originally I was going to suggest Pyrrhonists but in researching it further I found empiricist and changed my answer because I thought it was a better fit. Commented Aug 3, 2016 at 7:56

Colloquial British: "Negative Nancy"

"Negative Nancy" is perjorative, but "Doubting Thomas" also is traditionally; "Stop being such a 'Doubting Thomas'". The switch to being an expression of intelligent skepticism is very recent.

Both are generally used when someone is questioning the feasibility of an idea, whereas appelations ike "Debbie Downer" are more about emotional mood.

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    What I meant to say is that "negative Nancy" is not normally used to describe a skeptical person. I say that from the perspective of an American English speaker. In American English, "negative Nancy" is used to describe an excessively pessimistic person (someone who finds something to complain about in every situation). Is it used differently in British English?
    – pyobum
    Commented Aug 1, 2016 at 10:54
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    I think it's generally used when someone's expressing skepticism about an idea or belief, as a pejorative. At least traditionally, Doubting Thomas is used in a very similar way.
    – deworde
    Commented Aug 1, 2016 at 10:58
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    Quite possibly an AmE/BrE distinction. (Any other BrE speakers, please weigh in on this.) In AmE, I've only ever heard "negative Nancy" (and similarly, "Debbie Downer") used toward people who habitually focus on the bad aspects of daily life (and consequently bring down others' moods)--little or no connection to skepticism.
    – pyobum
    Commented Aug 1, 2016 at 11:08
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    @pyobum - As a BrE speaker I'll weigh in. Negative Nancy means someone who is negative; hence a pessimist and not necessarily a sceptic. Deworde appears to have conflated the two (I don't mean this as a criticism - I have done the same myself many times.)
    – AndyT
    Commented Aug 1, 2016 at 13:29
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    @deworde: You wrote "Both are used when someone is questioning an idea." That's a key point that probably ought to be folded into your answer instead of being mentioned in a comment – such an edit might thwart further downvotes. The two aren't complete synonyms, but I think you correctly point out there is some overlap in certain contexts.
    – J.R.
    Commented Aug 2, 2016 at 21:45

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