Part 0 · AI Without the Fog

What Are "Reasoning Models" and "Deep Thinking"?

Same puzzle, two modes: instant vs deep thinking; watch the time and cost gap, then a four-question quiz to feel when thinking is worth turning on

THE QUESTION THIS PAGE ANSWERS

ANSWER FIRST

What Are "Reasoning Models" and "Deep Thinking"?

Same puzzle, two modes: instant vs deep thinking; watch the time and cost gap, then a four-question quiz to feel when thinking is worth turning on

DECISION RULE

Make the claim earn its place. Use this page as a decision aid, not a definition to memorize. Connect the idea to one real task, one observable result, and one failure that would change your mind.

TRY NEXT

Write one question you could answer with evidence after trying this idea.

WATCH FOR

A conclusion that sounds complete but leaves the key assumption untested.

One-sentence answer

A reasoning model works the problem out step by step on scratch paper, then hands in the answer. It's slower and more expensive, but it gets hard problems wrong less often. One caveat: turning on deep thinking for a simple question is using a sledgehammer to crack a nut.

What "think first, then answer" actually means

Regular mode is like a quiz-bowl buzz: the question drops, you speak from the first thing that pops into your head. Deep thinking is like a long exam question: you list the constraints on scratch paper, try a few approaches, cross out the ones that fail, and only then copy the answer onto the sheet. The so-called "thinking" is just a few extra pages of scratch work. That scratch work is generated one word at a time too — so it's slower, and it costs more.

Same puzzle · two ways to answer

Here's a small seating-logic puzzle. Tap the two buttons below and watch how each mode answers. Start with Instant mode, then try Deep-thinking mode.

Puzzle: Family dinner, one row of 5 seats. Rules: ① Grandpa hates noise, so he sits on an end; ② the two kids (Xiaoming, Xiaole) can't sit next to each other; ③ Mom sits next to Xiaoming to help with the food; ④ Dad pours the tea, so he sits dead center. How do you seat them?
Time
Cost
Which questions are worth deep thinking

The rule in one line: if the answer has to be worked out step by step, turn it on; if you can look it up or see it at a glance, leave it off. Four questions below — you judge. Tap and you'll know if you got it.

A cheap little habit: default to regular mode. When it gets something wrong, or you can feel "this one's a bit twisty," turn on deep thinking and ask again. That's the best value.

The complete interaction cost of “What "think first, then answer" actually means”

“A reasoning model works the problem out step by step on scratch paper, then hands in the answer .” is a reminder that AI cost is not one price multiplied by one call. Input, output, retries, tools, waiting time, and human cleanup together decide what a task really costs.

Find what the bill repeats

The key variables behind “Regular mode is like a quiz-bowl buzz: the question drops, you speak from the first thing that pops into your head.” are usually repeated context, oversized output, retries after failure, and calls that do not produce useful progress. Removing wasted Tokens can reduce cost, latency, and concurrency pressure at the same time.

  • Reasoning model = scratch work first, then the answer : write out the working, then give the answer
  • Slower and pricier : what you buy is being clearly more solid on hard problems
  • On for hard, off for easy : don't take a sledgehammer to a nut

A cheaper call can make the whole workflow more expensive

Start with “The rule in one line: if the answer has to be worked out step by step, turn it on;” and keep a small table for input, output, retries, tools, and human review. Compare quality before and after optimizing instead of looking at one price in isolation.

From “What "think first, then answer" actually means” to “Same puzzle · two ways to answer”

“What "think first, then answer" actually means” grounds the problem in “Regular mode is like a quiz-bowl buzz: the question drops, you speak from the first thing that pops into your head. Deep thinking is like a long exam question: you list the constraints on scratch paper, try a f…”. “Same puzzle · two ways to answer” then moves it toward “Here's a small seating-logic puzzle. Tap the two buttons below and watch how each mode answers. Start with Instant mode, then try Deep-thinking mode”. Together, they show that the lesson is not just a conclusion to remember, but a claim with conditions.

Carry the judgment into the next situation

When analyzing cost, map the complete interaction first, then find repeated input, wasted output, and retries. A cheap individual call does not make the whole task cheap.

  • “What "think first, then answer" actually means”: Regular mode is like a quiz-bowl buzz: the question drops, you speak from the first thing that pops into your head. Deep thinking is like a long exam question: you list the constraints on scratch paper, try a f…
  • “Same puzzle · two ways to answer”: Here's a small seating-logic puzzle. Tap the two buttons below and watch how each mode answers. Start with Instant mode, then try Deep-thinking mode
  • “The closing point”: "Thinking" isn't mysterious : it's just a few extra pages of generated scratch text

The final “The closing point” brings the discussion to “"Thinking" isn't mysterious : it's just a few extra pages of generated scratch text”. The useful thing to carry forward is knowing which judgments must be revisited when input, scale, or risk changes.

✅ What this page wants to share with you

  • Reasoning model = scratch work first, then the answer: write out the working, then give the answer
  • Slower and pricier: what you buy is being clearly more solid on hard problems
  • On for hard, off for easy: don't take a sledgehammer to a nut
  • "Thinking" isn't mysterious: it's just a few extra pages of generated scratch text
Mark as learned Your reading progress updates automatically
← PreviousNext →

Keep reading

The next useful article in the thread.

ARTICLE DISCUSSION

Leave one useful thought here.

Keep the idea that clicked, the question that stayed open, or a small note for the next learner.

Discussing What Are "Reasoning Models" and "Deep Thinking"? AI Without the Fog
3discussionsArticle discussion · synced with the Circle
View in the learning circle
LF
Luca FerriData analyst
INSIGHTVerify first

This stopped me from equating “thinking longer” with “being more correct.” For complex tasks, I turn the reasoning into checkable intermediate results, which makes errors easier to locate.

ARTICLE DISCUSSION8 helpful
MF
Mei FloresProduct designer
QUESTIONQuestion

For everyday writing and simple extraction, is there any reason to default to a reasoning model? Beyond speed and price, what signals suggest that switching is worthwhile?

ARTICLE DISCUSSION5 helpful
HY
Harper YoungTeam lead
IDEAUsage policy

A team could start with a rule: use deep reasoning only when failure is costly, and use a normal model plus verification elsewhere. That controls cost without hiding all the complexity in model choice.

ARTICLE DISCUSSION4 helpful