Sonus Silentii By Philip Kaplan
I own a relatively expensive piece of electronic equipment that keeps breaking.
I corresponded with someone who works for the manufacturer. His response to me was (paraphrased), “we’ve sold thousands of these units and nobody else has complained. Therefore, our product must be good.”
His logic is wrong. Though his is a common assumption that companies make.
Just because nobody complained, doesn’t mean they’re happy. It’s entirely possible that 100% of your customers are unhappy, though nobody’s spoken up about it.
I tried searching Wikipedia for a name for this fallacy. I couldn’t find one so from now on I’m calling it “sonus silentii." It means "sounds of silence" in Latin. Which I thought sounded cool and is a pretty accurate description of what’s happening. It sounds kind of pretentious, so I’ll probably get smacked in the head if I ever really say it.
These already-named fallacies are close, but not quite right:
- Modus tollens (not a fallacy but probably the logic he thought he was using) or evidence of absence: Everyone who experiences a problem emails us. Nobody emailed us. Therefore nobody experienced a problem. The problem here is that not everyone who experiences a problem will email you.
- Hasty generalization - We sold 1,000 of these devices. 999 of the devices work fine, therefore yours works fine or is an isolated problem. Problem is, there’s no way to be sure that any or all of the other 999 devices work.
- Argument from ignorance - We don’t have evidence that these things are broken, therefore they must not be broken. It’s possible they’re broken even if you don’t have evidence (and really, I’m giving you evidence by showing you how mine broke).
If this fallacy already has a name, let me know on Twitter (@pud) or something and I’ll update this post.