Most of us – most of the time – like to believe the world is a rational place.

No matter what soul-capsizing unpleasantness befalls us, there’s a Pyrrhic comfort to be had in recognising its causes. For every violent burglar there’s a story of poverty or addiction. For every knife-bothering mugger there’s the peer pressure of a violent culture or a lack of moral education. For every murderer; a motive. Even when a genuine monster arises – a spree killer or psycho – we can rubber-stamp our way past the revulsion with the catchall of “mental illness” and blame a deficiency in social care. It doesn’t make it any less frightening of course, but the fear is at least nameable: a taxonomical bandage on the wound.

For crime writers – particularly those of us in the mewling bastard-child subgenre The Detective Mystery – that presents an interesting problem.

A Serpant Uncoiled

See, on the one hand a large part of our craft is to construct an enigma which is inherently solvable. Our heroes and heroines must think, intuit and fight their way towards a solution which – if the Big Reveal is well handled – readers could have reached themselves but didn’t. That tends to imply an essentially rational set of parameters, on the grounds that neither readers nor heroic detectives can be expected to solve (say) algebraic equations, if the “x”s keep turning into bloody Unicorns.

On the other hand, rationality can fly in the face of the Crime Writer’s other obligation: to disturb. Nothing engages a reader – nothing gets him or her investing in a story – quite as well as fear, and so we crimecrafters like to trickle a frosty little shiver down our audience’s collective spine, leaving them questioning their own security. Writers from the horror genre have understood for years that the most bowel-loosening monsters are always human, or at least humanish, albeit possessed of some unknowable, empathy-rejecting quality. In other words: the best fear-mongers rely upon a trace of The Irrational.

You begin to see the dichotomy.

In the crime world, those same fright-night compulsions take the form of the ever-popular Serial Killer: a predator of humanity, as unknowable and apathetic as any fang-flashing special effect. Nonetheless, writers inevitably build-in the behavioural logarithm of the “modus operandi”: the idiosyncratic rulebook which guides the nutter’s nuttery. Maybe he’s murdering his way through the alphabet, or targeting people with small feet, or the Virgin Mary told him to punish people wearing tweed, or… or… or…

The point is, even when engaged in the most primal human pursuit there is – imagining bogeymen in the darkness – still we crime writers can’t help injecting a substrate of rationality: bringing it all back down to earth.

I think that’s a pity.

The irony is that the “real” world is positively frothing with The Irrational anyway – or at least the Not Provably Logical. The vast majority of the planet’s population continues to define itself according to its faith, for example. Most of us cling to our knock-on-wood superstitions, and at the very least all of us will still steal a guilty glance at our horoscopes once in a while. More importantly, the overwhelming balance of “real” crime takes the form of random, unpredictable acts of hot-headed violence, with nary a mission-driven-psychopath in sight. Now, I wouldn’t dare pour scorn on people’s beliefs, and I completely accept that “realistic” criminality – with all its chaos and stupidity and lack-of-premeditation – rarely makes for a compelling detective mystery…

…but it does seem rather difficult to reconcile – say – an insistence on Real Empirical Forensic Science in our stories, or a predilection for the Convoluted Premeditated Murder, with a reality which is so deeply entrenched in supernatural belief and random horribleness.

My theory is this: Perception Is Key. Bear with me here.

Contract by Simon Spurrier

I’ve been fascinated by the different ways people perceive things ever since a youthful adventure in a graveyard, during which two otherwise sensible friends swore themselves silly they’d “definitely seen a ghost” where I simply hadn’t. In a way, the majority of detective fiction revolves around that same disparity: the idea that some people – usually our enigma-solving heroes – see things just a little differently from the rest of us; intuiting faster and deeper as a result. In effect their perceptions are better than ours, and that’s usually the leg-up they need to rationally solve their rational mysteries, while the rest of us lag behind.

Without meaning to – without having the slightest concept of any of this stuff at the time – I approached my novel A Serpent Uncoiled from the completely opposite direction. Thanks to a traumatic past and a crippled psyche, my detective – the rumpled, drug abusing, guilt-dodging fuckup Dan Shaper – is slowly losing control of his own senses. Suddenly I found the shoe on the other literary foot: Shaper’s not permitted to just assume he can trust his brilliant deductive skills, nor rely on his eye for hidden detail, because either one could be built on a platform of fizzing irrationality. His broken brain leaves him unsure whether the things he’s experiencing are truth or delusion. If it’s the latter, it means he’s going insane.  If it’s the former, well… that’s even worse, because it means his world is a far stranger and more irrational place than he ever dared believe.

Most of us, remember, like to believe the world is a rational place. That’s especially true if you can’t trust your own cerebellum.

I’m not going to pretend I approached all this with some superclever strategy to overturn the mechanics of the detective mystery. I simply wanted to tell a creepy story about a guy who’s falling apart at the seams, who has to hold himself together long enough to catch a killer. But, accidentally, the possibilities which suddenly emerged were profound. Abruptly I found myself able to spin a mystery with all the favourite tropes of the genre – the clues, the M.O.s, the forensics; all of them comfortably grounded in rationality – and then to gaze upon them all through the lens of the chaotic and the horrific.

Suddenly every street-level crime becomes random and tense and terrible. Suddenly the Premeditated Act becomes suspect, superstitious; unpredictable. And above all, suddenly – like returning to that first primal terror – the bogeymen in the dark become a real monster again.

So that’s my accidental manifesto. Poor old Dan Shaper, that wrongheaded bastard, really got me thinking. He’s made me wonder why we writers are so determined to apply order to that which is inherently disordered – to normalise the inherently spooky, to disempower the inherently horrific – when the real world is so much stranger, and less knowable, than we pretend. Why must we regard it in such a determinedly rational shade?

In my experience – which is really Dan Shaper’s experience – seeing the world through irrational eyes, as we all ultimately do, is a far more compelling, and far more frightening, experience.