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Knox’s Commandments – The 10 Rules of Golden Age Detective Fiction, Part I

In 1929, Golden Age mystery writer and monsignor of the Catholic Church Ronald Knox formulated 10 rules that he believed should set apart proper detective fiction from what he considered “shockers”,  works that primarily dealt with heroes fighting criminal enterprises rather than detectives attempting to solve a mystery. Called Knox’s Commandments, these rules would quickly become the standing guidelines for the Detection Club, which I discussed in my previous post. Other sets of similar guidelines would emerge in the era – such as S.S. Van Dines’s “Twenty Rules for Writing Detective Stories”, actually published before Knox’s own Commandments – but it would be Knox’s rules that would by and large dominate the Golden Age of Crime, supported as it was by the Detection Club (which included Agatha Christie) and its roster of talented mystery writers.

Even Knox never expected full compliance with the rules he set out – he freely admitted that some truly worthy mystery works would occasionally break the rules and end up the better for it – but by and large these were considered a good set of guidelines, and authors would stray from them at their own peril. In my next post in this series, I intend to go through Knox’s Commandments one by one and discuss how they either apply or no longer apply in mystery fiction. For now, I’ll just post the Commandments themselves for your consideration.

Keep in mind that these rules were written in a very different time – since the rules are dated, some of the rules are phrased in a way that makes them very uncomfortable to modern sensibilities, though they wouldn’t have been considered out of place in the era they were written. I’ll discuss some of them in more detail in my next post in this series.

Knox’s Commandments:

  1. The criminal must be someone mentioned in the early part of the story, but must not be anyone whose thoughts the reader has been allowed to follow.
  2. All supernatural or preternatural agencies are ruled out as a matter of course.
  3. Not more than one secret room or passage is allowable.
  4. No hitherto undiscovered poisons may be used, nor any appliance which will need a long scientific explanation at the end.
  5. No Chinaman must figure in the story. (I told they were dated!)
  6. No accident must ever help the detective, nor must he ever have an unaccountable intuition which proves to be right.
  7. The detective must not himself commit the crime.
  8. The detective must not light on any clues which are not instantly produced for the inspection of the reader.
  9. The stupid friend of the detective, the Watson, must not conceal any thoughts which pass through his mind; his intelligence must be slightly, but very slightly, below that of the average reader.
  10. Twin brothers, and doubles generally, must not appear unless we have been duly prepared for them.

The Detection Club

Knox’s Commandments – The 10 Rules of Golden Age Detective Fiction, Part 2

Comments

  1. Poor old Watson! He’s not that stupid. I wonder how Knox decided on “the average reader” and his (it would be his, wouldn’t it) intelligence level was?
    Entertaining stuff.

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  2. Oh Wow! I think most of today’s mystery writers break EVERY single one of those rules, frequently in the same book!

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  3. ‘No Chinamen’ – sounds like somebody was not a fan of Sax Rohmer! Lol!

    Slightly off-topic, the term ‘shocker’ (Originally ‘shilling shocker’ because that’s what they cost) always makes me smile.
    In modern Australian slang, anything which is awful, or just plain bad, isn’t shocking, it’s… ‘a shocker’!

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    • Susan*, when I read the commandments for the first time, I immediately thought about how many times Agatha Christie’s upper class characters would be rude to Poirot, and imagine him less than capable… (Until, of course, he pegged one of them as the murderer!)

      Hmmm… “a shocker” instead of shocking. I’m going to try to incorporate that into one of my sentences today…

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  4. Hello,

    I am really enjoying these posts on the Detection Club…! In fact, I love your website… and hope that it’s ok with you that I have linked your website on my blog as one of my favourite websites for cozy mysteries…!

    Thanks…!

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  5. Interesting – I’ve never heard of Knox’s Commandments but have heard of many on the list, especially No. 10 which most books on writing mention.
    Ann

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  6. Wow! This Detection Club is fascinating I never knew about it’s existence. Knox ‘s 10 Commandments well…# 5 really?? #9 what can I say?? Never thought of a sidekick that way before. You have to wonder how he would have written them today.
    Can’t wait for your next post on this topic. Thanks !

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  7. I like those rules. They would probably fit in todays world. My only problem is rule 9, the Watson intelligence should be equal to or slightly above the reader. I don’t care for the “stupid” sidekick. Thanks for sharing these rules as I read them I could see how the authors devised their plots.

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  9. Have really enjoyed the 1st two installments of your report on the Detection Club. I had a vague knowledge about it’s existence, but no real information or insight. Can’t wait for the “thrilling conclusion”
    Thanks Again!!

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  10. I violate the second rule in my mysteries by inserting the thoughts of the villian in italics every so often.

    By the way, Agatha Christie’s autobiography from the early 1980’s is fascinating. She includes quite a bit of information about the progression of her writing methods.

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  11. can’t believe most of the bloggers here were so surprised by what they read.I knew the Knox rulles when I was 10 (1952). The detection club wrote one of the best books in detection fiction ‘the floating admral’. each chapter written by a different famous author who has no idea how the previous chapter writers saw the rest of the book unfolding. they each explain in synopsis form at the end of the novel how they thought it should have finished. a detective buff’s dream and delight.

    Reply

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