On A Decalogue of Our Own

Back in 1929, priest, crime writer, Detective Club member Father Ronald Knox penned ten so-called commandments for the drafting of proper crime fiction, often remembered in their incredibly abridged forms. Martin Edwards’s own book The Golden Age of Murder implies that the jury is out on whether Father Knox was being entirely serious with these rules, but that didn’t stop other crime writers from taking up the mantle and putting forth their own opinions on what makes the ideal detective story, as evidenced by American writer S. S. Van Dine’s far less playful ruleset.

Serious or not, there’s a little something to be said about rules as a guideline, if not as hard-set laws, especially for a genre seen as “sporting” as the Golden Age detective novel often was. What is a game (even a metaphorical one) without some mutual understanding between the players? And if nothing else, take it as advice from experts, and with all tips of the trade you are free to take them, or not. I don’t think rules should be touted as absolute, nor do I think that works should be criticized for breaking them, but to admonish them as elitist or pointless is a bit narrow-minded.

As a part of a mental exercise a few years ago, I took up the task of writing my own “Decalogue” — a set of ten rules which would define my own crime writing, which just so happens to be entrenched in the conventions of the Golden Age and its focus on games of detection. As it so happens, J.J. over at The Invisible Event just published his latest in a long series of posts analyzing and dissecting the Knox Decalogue, and I felt inspired to share my own Decalogue in the spirit of discussing rules of the genre.

As with all things on this blog, keep in mind that what I am writing here is not meant to be any sort of rules I’m trying to impose on you. While I do write, I am an amateur, unpublished author who just has opinions and wants to share them. These are simply guidelines I set down for myself and my own mystery writing. Also, unlike Van Dine, I tried to stay away from elements of setting, theme, character and politics, and I made my focus squarely set on the nature and matter of clues and reasoning. Without further ado, let’s get into The Stump Dialogue.


Withhold nothing from the reader.

Withholding, in this context, will simply be to omit any allusion, direct or indirect, to any piece of information or evidence central to the mystery of which the detective is aware. A puzzle ought be a challenge, not an impossibility; the writer should show good faith in trying to allow their reader to fairly figure the solution to the mystery on their own. If information cannot be told, permit it to be figured.

Place no prerequisite of knowledge on the reader beyond that of the language in which the book is written.

Even if you give the reader all of the information they need to solve the crime, if the cinching detail knowing that aluminum only becomes malleable at 600 degrees Fahrenheit, the mystery is not fair play. The master of the craft can hide integral clues in plain sight amidst the more useless of details; so, in cases where scientific knowledge plays into the mystery, there is no reason not to consider knowledge of the scientific mechanics at hand a clue and to present it in very much the same way. Should discovering this expertly-placed knowledge in no way serve the puzzle and only lends itself to frustrating your literary sleuths, or is something which the narrator and/or investigator may immediately be aware of, it is most often best to proclaim this information as early as would better serve your puzzle.

This equally goes for domestic knowledge, cultural notes, or insider knowledge of institutions like the police.

The victim and the culprit may not be the same person, excepting in cases of multiple problems, multiple culprits or multiple victims.

With a death in the locked room, the solution may not begin and end at the victim driving the knife through their own chest. Should the plot of a mystery turn exclusively on the abduction of an affluent child, followed by ransom, the solution should not begin and end at the child faking his own capture.

Suicide or a faked death may never be the absolute solution. It is, simply, “too easy” on the culprit and the writer. However, a culprit may use any means of making themselves a victim in order to deflect or obfuscate guilt, including harming, killing or faking an attack unto themselves before or after committing their true murder — in other words, suicide may be a misdirection.

Excepting explicit collusion, no more than three individual criminal plots may be hatched at the same time, in the same location, all a part of the very same overarching incident, by unrelated peoples.

Bogging down the focus of apprehending the perpetrator of the book’s primary crime-at-hand with multiple individual but conveniently interweaving criminal plots only lends itself to unnecessarily convoluting the suspect pool; the incidentiality that leads to these plans’ intersections in the end can only ever border on the contrived if it is not an act of deliberation and collusion between the multiple perpetrators.

The solution may never rely entirely on a feat of acrobatics or physical ability.

While a suspect’s physical ability or inability to perform a specific, noted task may become a clue in and of itself, the solution must be majorly as much a test of the culprit’s mental acuity as it is the investigator’s and the reader’s. Any trick that is simply and only possible by some superhuman feat of athletics is disallowed.

Gender or racial psychology is not permitted as a clue.

A woman may select poison as her murder weapon because it is practical, for reasons interpersonal to her and her victim, or for the sake of any trick she may have in mind. A woman may not select poison because she is a woman.

In any case where there are two or more viable suspects, the final clue needed to distinguish the culprit from among them may not be that it is a more feminine or more Anglo-Saxon means of murder. If the hard evidence isn’t enough to sufficiently nail one of your suspects as the criminal, rework your mystery.

Any distinctive feature to the setting or set-up of the mystery should play into the criminal plot.

That is to say, the murder plot should ideally not feel as if it could have happened anywhere. The killer’s choice for when and where they committed the crime should be justified by their methods for committing it and avoiding detection. Otherwise, how do you explain the killer choosing to kill at a theme park, or in a restaurant, or at the theater, in front of witnesses!

Red herrings should feature meaningful alternative explanations.

A misleading clue that promotes interesting reasoning that helps lead the detective and the audience to the true solution of the mystery is great; but if the truth is that the clue truly meant nothing, that’s almost inherently an anticlimax.

The killer’s methods and motive should have no disconnect.

The way the killer commits the crime is as much a clue as any other. If, say, a loving daughter is coerced into murdering her father by an outside force, she would not choose heinous or cruel methods — to have her do so is misleading in the greatest way. And if, for example, the killer wishes to frame another character for a murder, it makes no sense to have them arbitrarily commit another murder that the chosen scapegoat would never be able to commit. These sorts of mistakes confuse complexity with interest.

Separate the characters’ motivations and your own.

So many authors have characters behave in ways only because it promotes the puzzle. Artificiality comes with the territory, but unreality should be avoided as best as one can. To have characters behave in odd ways only because it works for the puzzle at best can tip the author’s hand, and at worst ruin the reader’s faith in you. Mysteries where the character behavior is organic and realistic make puzzles that better play on the natural thoughts of the audience.

3 thoughts on “On A Decalogue of Our Own

  1. Mikhail Turkhan November 16, 2020 / 3:09 pm

    My comments:

    1. Withhold nothing from the reader.

    Definitely agree. Any withholding, if it does happen, should be resolved really quickly, preferably within the same page.

    2. Place no prerequisite of knowledge on the reader beyond that of the language in which the book is written.

    Generally agree, however, if the author gives some hints that the knowledge area is important, then it’s enough to create the sense of inevitability. With the aluminium example, this would be things like having characters discuss metal melting points even without mentioning the precise melting point of aluminium.

    3. The victim and the culprit may not be the same person.

    Mostly agree in order to avoid copouts, but occasionally, I feel a suicide or a self-kidnapping can be done well, provided it has actual non-obvious positive clues pointing to it, rather than just “it was a suicide, because none of you had the motive, duh”.

    4. No more than three individual criminal plots may be hatched.

    Strongly agree, overloading a situation with malicious plots and culprits is a common was of providing cheap, unsatisfying plot twists. In fact, I’d limit the number of separate plots to two, with three possible only with really skilled authors.

    5. The solution may never rely entirely on a feat of acrobatics or physical ability.

    I agree that a detective novel implies some necessary deception on part of the criminal or their accomplices, however, the primary person whose mental acuity is important in a detective novel is the author. Revealing hidden abilities in a character who never gave any indication of having them is basic clue-insufficiency, but it’s not cheating if there were clues about these abilities before the reveal (e.g. the character was mentioned to work as a circus acrobat in the past).

    6. Gender or racial psychology is not permitted as a clue.

    Strongly agree, this is clearly a copout. In fact, if characters advise such reasoning, they must be revealed as wrong or, at least, wildly speculating.

    7. Any distinctive feature to the setting should play into the criminal plot.

    Ideally, yes, although violations here as not as pernicious in a genre that allows some implausibility. Still, if the setting is especially distinctive, there needs to be some rationale.

    8. Red herrings should feature meaningful alternative explanations.

    Strongly agree. This principle is unrealistic, since in real life, things sometimes happen randomly and seemingly vital clues can have a banal explanation. But this is the part of the genre where lack of realism is not only acceptable, but mandatory. Violating it is a cheap, disappointing way to create falsely intriguing clues.

    9. The killer’s methods and motive should have no disconnect.

    Vital requirement to avoid plot holes.

    10. Separate the characters’ motivations and your own.

    Useful advice in all fiction, not only in detective stories. In detective fiction, it also reinforces rule 8 – characters shouldn’t behave as if they wanted to deliberately provide a red herring to the author, with no actual reason for them to act so suspicious.


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