- Problem
- AI's factory setting is eager and agreeable, so a single question gets you a single cheerful answer.
- Fix
- run four questions in order — be a sceptic, split fact from guess, name what would prove it wrong, then commit to one answer.
- Payoff
- you see the catch before you act, not after.
Ask an AI “is this a good deal?” and it will almost always tell you yes. Not because the deal is good. Because agreeable is its factory setting. It wants to be helpful, a cheerful yes feels helpful, so that’s what arrives, catch and all.
The fix isn’t a cleverer question. It’s four of them, asked in order. Each one does a job the single eager question skips. Here’s the whole method, start to finish, on one ordinary thing: a holiday deal someone’s sent you and you half want to believe.
One: make it argue against the deal, not for it
I make this the first move on every answer that matters. Left to itself, the AI sells you the sunshine. So give it the opposite job first. Tell it to be the tight-fisted friend who assumes every deal hides a catch and finds that catch before saying a single nice thing. Do this and it stops describing the infinity pool and starts hunting the resort fee, the “airport” that’s a two-hour coach ride from the resort, the “from” price nobody has ever paid.
Two: split what it knows from what it’s guessing
Of the four, this is the step I lean on most. Now make it sort its answer into two piles: what the page in front of you says, and what it’s filling in from thin air. “Breakfast included” belongs in the first pile only if the deal page says so. If it’s a confident guess, it goes in the second, where you can see it for what it is.
Three: ask what would prove it wrong
This is the question almost nobody asks, and the one I added last — it’s the one that changed how much I trust the answer. Make the AI name the exact thing that would expose the deal as a dud: a tripwire, not a vague worry. Something like “if the total at checkout comes out over £900, the headline price was a lie.” Now you’re not weighing a foggy feeling. You’ve got one number to watch, and the deal either trips it or it doesn’t.
Four: make it commit to one answer
Here’s where I stop it hedging. Last, no fence-sitting. Book it or don’t, in one line, with how sure it is: low, medium or high confidence. Nobody has ever stood at the checkout with their card out, reading a balanced six-paragraph essay on the merits of both sides, and felt helped. One verdict, one confidence level, and you can decide.
The whole thing, ready to paste
Here’s the version I keep to hand. Drop your deal in and run this:
Here’s a deal I’m considering: [PASTE THE DETAILS]. Run it through these four steps, in order, and label each one.
ROLE: Be a tight-fisted friend who assumes every deal hides a catch. Find the catch before you say anything good about it.
FILTER: Make two lists — what the deal states, and what you’re assuming or guessing.
RISK: Name the single thing that would prove this is a bad deal: a specific number or fact I can go and check.
VERDICT: Give one answer — go for it, or don’t — with a confidence level: low, medium or high.
That’s the whole thing. It works on the holiday, and it works exactly the same on a builder’s quote, a contract, or an email you’re not sure how to answer. Four questions, always in that order, because each one clears the ground for the next.
That’s the method, free to keep. If you want the longer version — where each step came from, and prompts you can lift for harder calls — it’s all written up in one place: the Prompt Stack.
Ben tests ways of getting reliable answers from AI on his own investing — documenting what each model got wrong, what each one caught, and the prompts that survived the cuts. About Ben →
The site runs AI on real investing decisions. Start with the Prompt Stack for the four-stage framework, or the Field Guide PDF for the condensed version — free, no email.