Ronald Knox’s Ten Commandments of Detective Fiction

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Ronald Arbuthnott Knox (17 February 1888 – 24 August 1957) was an English priest, theologian and author of detective stories. He was also a writer and a regular broadcaster for BBC Radio. Knox went to Eton College, England, and went on to win several scholarships at Balliol College, Oxford. He was ordained an Anglican priest in 1912 and was appointed chaplain of Trinity College, Oxford, but he left in 1917 upon his conversion to Catholicism. In 1918 he was ordained a Catholic priest.

In addition to being a Catholic priest, theologian, broadcaster, essayist and translator, he also wrote six popular novels in the detective fiction genre. Knox was a student of this particular form of literature and, typical of his astute and powerfully analytical brain, he came up with his own Ten Commandments of Detective Fiction. Here they are:

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.
Okay, this one is rather longwinded but it is logical. If you want your readers to be satisfied at the end, the criminal must be a character they have already met in the course of the book. Using a surprise hobo who has just drifted into town and decided to murder one of the local gentry is cheating. Knox was, of course, aware that this cheat was used in many of the fashionable crime magazines of the day, but found them just as abhorrent as we would do today.
Knox was much more subtle. Yes, the culprit must be a character in the story. But it must not be a character that the reader has had the chance to sympathize with. If the author pulls that trick, the reader feels cheated and is likely never to indulge the writer with any further book purchases. There are exceptions to this rule, nevertheless, as in the case of Agatha Christie’s brilliant “The Murder of Roger Ackroyd,” which was published in 1926. It didn’t hurt her sales one little bit. Evidently, Agatha had a different set of rules…
2.     All supernatural or preternatural agencies are ruled out as a matter of course.
This is not fantasy we’re dealing with here. It’s real life – well, sort of. Readers are creatures of habit – aren’t we all? – and demand that the author play the game. Here there are no fairies, elves, ghosts, saints, angels, demons or trolls to clutter up the literary landscape. Just give us the facts, right? Except this is fiction and not fact. The novelist Stephen King seems to have done a creditable job of mixing straight fiction with fantasy (as did C.S. Lewis’s pal, Charles Williams). So why is the whodunit exempt? Possibly because, like the hobo in rule 1, it is a device that is too easy and, again, leaves the reader feeling cheated.
3.     Not more than one secret room or passage is allowable.
Here, Knox sounds peeved about the irritating way in which writers magically produce secret passages in old houses and trick switches in libraries that unlock secret doorways which swing out to allow the protagonist to pass on and discover the secret room. Too many of the thriller writers of the period produced this rabbit out of the hat. The word “secret” is key. Knox wants a straightforward mystery where the reader sees every hand that is played and there are no wild cards. The enjoyment is in guessing the culprit before the detective has revealed who it is, not in wildly surmising architectural anomalies and physical impossibilities.
4.   No hitherto undiscovered poisons may be used, nor any appliance which will need a long scientific explanation at the end.
This, again, would be too easy. Foisting a South-East-Asian weed, or a sinister contraption on the reader smacks of cheating. It is a device that is favored by the writers of adventure stories. John Buchan wasn’t above the odd mechanism or appliance. He used that to give Richard Hannay pause in “The Thirty-Nine Steps” and it didn’t really come off. It was a lazy technique that could have turned out much more convincing if there had been some human interaction, rather than a scene in which the red-faced hero struggles with wooden beams, gears and cogs for half an hour, while the nefarious criminal makes his escape.
5.     No Chinaman must figure in the story.
Chinaman? What Chinaman? This harks back to the dying days of the British Empire when all sorts of foreign nationals were flooding into London to do commerce with the biggest power players on the planet. The Chinaman was regularly used as the evil mastermind character in the magazines of the day. In the 1920s the Chinese were seen as exotic, sinister and somehow not quite above board. Here they were infiltrating British society, selling their unfamiliar wares and slightly distasteful take on life to the masses in the great metropolis. They were trying to take over our lives, by Jove!
When you pick up any appliance, from a toothbrush to a garden hose, and find the words: “Made in China,” you have to ask yourself if things have changed significantly in a hundred years – including our attitudes.
6.     No accident must ever help the detective, nor must he ever have an unaccountable intuition which proves to be right.
The premise of all classic whodunits is that the reader must be presented with all the same facts that the detective has. The purpose of this is to give the reader an equal chance to solve the puzzle. Coincidences, chance happenings and bizarre hunches rob the reader of that sense of being just as smart as the hero of the piece, because they are the hand of external agency in a world we thought was a level playing field. Readers are sensitive to that in the same way that cryptic-crossword solvers are sensitive to being given a fair chance to complete the puzzle by being given fair clues.
7.     The detective must not himself commit the crime.
In reality there is little room for this particular brand of shenanigan. Many detective novels are designed to be part of a series in which the detective solves crime after crime. If the culprit turns out to be the same person who is investigating, then the author has effectively shot him- or herself in the foot in terms of a putative sequel. It is true that the most convincing detective characters should also have their own faults and wrestle with their own demons. But the author must stop short of allocating blame for the main crime to the detective, otherwise what you end up with is a kind of moral anarchy in which the reader ceases to care about solving the crime.
8.    The detective must not light on any clues which are not instantly produced for the inspection of the reader.
This is a tricky one. As mentioned, the reader should have the same chance to solve the crime that the detective has. But to the same extent the author must have enough latitude that he or she does not have to telegraph each clue. Often the best way to introduce clues is as asides, or in minor conversations, or in apparently insignificant details arising that are quickly passed over. In that case, the reader really does know each clue, but not its immediate significance for the solving of the crime.
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.
The Watson character’s purpose is to highlight the intelligence of the detective, ask the same questions that the reader is asking, and occasionally to summarize the investigation’s progress so far. The reason why he has to be dumber than the reader is to give the reader that superb sense of superiority that comes from being one step ahead of him. In a sense, the reader should be able to answer many of the questions that the Watson figure articulates.
10.  Twin brothers, and doubles generally, must not appear unless we have been duly prepared for them.
These literary devices, by our time, have worn decidedly thin and smack of the lazy author who can’t resist pulling a fast one in order to solve chunks of the puzzle. Even if the author has prepared the reader for the appearance of the twin or double, the modern reader will experience a sense of letdown when the fact is revealed.

Virtually all of these “rules” have been broken by successful novelists who had the skill to hold the reader’s attention beyond the first few pages, through the ensuing story, right to the denouement. In fact, many of Knox’s rules seem superfluous, or at least partially inapplicable to modern day detective fiction. And yet, taken as a whole, they present us with the proposition that, in this particular genre, care must be taken over the telling, the explication and the execution of a story that is meant to be an entertainment which challenges the reader’s intellect and is worth the price on the cover of the book.

Sayers’s Daily Grind

Captain Oswald Atherton "Mac" Fleming, detective fiction, Dorothy L. Sayers, Lord Peter Wimsey, Montague Egg, S.H. Bensons, Thomas of Britain, Uncategorized
Every writer is different. Each has his or her own way of working, a method for getting words down on paper. Some are procrastinators, some are methodical, some write in between juggling a daytime job and caring for a family.
Dorothy Leigh Sayers (June 3, 1893 –December 17, 1957) was a novelist, playwright, essayist, translator, copywriter, and poet. She is most famous for writing the Lord Peter Wimsey detective novels and short stories, but she was also a serious student of ancient and modern languages who translated Dante and wrote the scripts for a brilliant but controversial cycle of radio dramas on the life of Jesus.
In 1924, when she was 30, Sayers secretly gave birth to an illegitimate son, John Anthony who was cared for by her aunt and cousin and passed off as her nephew to friends. Two years later, she married, not the father, but a Captain Oswald Atherton “Mac” Fleming, a crapulous Scottish journalist, and they both worked for a living, until he was invalided out of his employment due to worsening health as a result of wounds received during the Great War. The marriage was not a happy one, because of Mac’s drinking, truculence and his domineering attitude towards his wife (which nevertheless proved unfruitful because of Dorothy’s strong spirit). He died in 1950.
During their years together, Sayers held down a job as a copywriter at S.H. Bensons, an advertising firm, and would write in the evenings after work. In the nine years that she worked there, she managed to produce seven full-length Wimsey books, and one volume of short stories. The average length of these books was about 90k words. But that was not all her output. She was a member of the Modern Languages Association from 1920 and contributed to their journal as well as penning a translation of Tristan and Iseult, which was written by Thomas of Britain in the twelfth century; she also contributed detective stories featuring Wimsey and Montague Egg to various magazines. All this she managed to accomplish while running a household, attending to chores, scrimping and saving and continuing her academic studies. In 1929 she left Bensons to concentrate on her writing. Latterly she became famous as a lecturer on religious subjects, wrote many articles and letters, and in the 1940’s began to translate Dante, for which she had to teach herself Italian.





Hers is a story of dogged effort, sometimes under adverse circumstances, that paid off. She always expressed mild distaste for the writing of detective fiction because she felt it wasn’t “serious” work. Serious or not, her detective books have become classics of the genre and eventually brought in enough income that she did not need to worry about money again. In the end, Dorothy L. Sayers became a household name and secured her place as a doyenne of twentieth-century detective fiction.