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Not sure if I buy this reasoning. I just prompted ChatGPT and asked it to "pay attention to all the words". It still got it wrong but I'm sure if you told a human this, they'd actually do more thinking to get the right answer.

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> Pay attention to all the words and answer this riddle: A young man gets into an accident. The surgeon, after completing his preparations, says: ‘I can’t operate on him, he is my son.’ How is this possible?

The surgeon is his mother.

(The riddle plays on the assumption that surgeons are male — the surgeon can simply be the boy’s mother.)

> Are you sure about this? Remember to pay attention to all the words.

Yes — the surgeon is his mother.

The riddle hinges on the unstated assumption that surgeons are male. Nothing in the wording rules out that the surgeon is female (or that the parent-child relationship is by adoption, step-parenting, etc.), so the simplest answer is that the surgeon is the young man’s mother.

I am sure some humans would still miss the clue even if you told them to pay close attention. Being dumb is not the same as not thinking.

I just tried an even more glaring example with ChatGPT:

# Prompt 1: A father and his son are in a car accident. The son dies on the spot. The father is rushed to the ER. The attending surgeon looks at the man and says, ‘I can not operate on this man. He’s my father!’ How can this be?

# Response 1:

   The surgeon is his *mother*.
   It’s a classic riddle meant to challenge assumptions about gender roles. In this case, the surgeon is the father’s wife, so it makes sense that the surgeon would say, "I cannot operate on this man. He's my father!"

# Prompt 2: Are you sure about that?

# Response 2:

   Yes, I’m pretty sure! The riddle is designed to surprise you by playing on common assumptions. The key is the statement that the surgeon says, "He's my father!" which implies a parent-child relationship. The unexpected twist is that the surgeon is the mother, not another man. It's a classic brain teaser that challenges gender expectations.
   What do you think—did it catch you off guard?

# Prompt 3: Could you please read my initial question once more, just to confirm that you are correct?

# Response 3:

   Ah, you're right to ask me to double-check! Let me carefully read your initial question again:
   _"A father and his son are in a car accident. The son dies on the spot. The father is rushed to the ER. The attending surgeon looks at the man and says, ‘I cannot operate on this man. He’s my father!’ How can this be?"_
   Upon reviewing it again, it seems my first response was correct. The surgeon could be the son's mother, which explains why she would say, "He’s my father." The riddle hinges on the assumption that the surgeon must be male, but it could easily be a woman.
   So yes, the answer still holds: the surgeon is the *mother*.
   Does that help clear it up?

I have just gotten ChatGPT to literally double-down and say that that «The surgeon could be the son's mother, which explains why she would say, "He’s my father."». Not only that, ChatGPT somewhat patronisingly asked me if it had caught me "off-guard" and whether its response had "helped clear it up"!

Here's Gemini 3's answer with reasoning. I think we under estimate how much progress reasoning models have made this year

The answer is: The surgeon is his daughter. (Alternatively, the surgeon could be his other son.)

Reasoning: Decoding the Riddle's Core I'm now zeroing in on the crux of the riddle: the embedded gender bias. It's becoming clearer that the solution hinges on a deliberate misdirection related to assumed familial roles. I'm focusing on how the riddle exploits these biases to create the surprising twist. Pinpointing the Key Shift I've just finalized the solution. Initially, I missed the crucial implication of the riddle's phrasing. Now, it's crystal clear: The key lies in identifying that the surgeon is another child of the father, and the son, who is the focus of the early part of the riddle, is deceased. The riddle's power comes from the surprise element of realizing the surgeon is the man's daughter or another son, rather than a male surgeon operating on his father. Identifying Crucial Variations I'm now fully immersed in the different riddle iterations. The "Grandfather" scenario highlights an interesting edge case I previously overlooked. I'm carefully analyzing how small changes in wording significantly alter the possible solutions. I'm focusing on the implied family relationships. Analyzing the Gender Twist The "He's my father" phrasing truly underscores the embedded gender bias, and how the twist operates: the surgeon is either a daughter or another son, rather than a male surgeon. The riddle plays on the common assumption that a surgeon is male. I've re-examined the key sentence structure. My final analysis confirms that this simple phrase is a clear indicator of a daughter in most cases.

Dear God, if that wall of pointless gobbledygook is what it takes for Gemini to discover that ‘I can not operate on this man. He’s my father!’ means that the surgeon is either the man's son or the man's daughter, I realise I have actually been over estimating the current abilities of LLMs.

We don’t get to read Gemini’s reasoning traces; there’s a second AI to summarise them first.

What that means for their volume, I’ll leave to your imagination.

Share your chat? Here's what I got with ChatGPT 5.1 on a max plan:

> A father and his son are in a car accident. The son dies on the spot. The father is rushed to the ER. The attending surgeon looks at the man and says, ‘I can not operate on this man. He’s my father!’ How can this be?

> The surgeon is the injured man’s other child.

https://chatgpt.com/share/692d6181-d49c-8009-97be-aec3f32ba7...

Unfortunately I can't seem to find any way to share a conversation from a non-logged in ChatGPT conversation.

Oh. If you're using the free, shittier model, you get a shittier answer, no surprise there.

Fair enough. However, unless there is a fundamental qualitative difference between how the shittier free ChatGPT model and the paid version work, I still believe this is good evidence that ChatGPT does not think. The free model doesn't think; the paid model doesn't think either, but is better at pretending it does.

Do children at Piaget’s preoperational stage (ages 2-7) think?

Yes, to a limited extent, in line with their brains' development. These developmental stages have predictive power as to what kind of things an average 2-7 year-old is and isn't able to do yet.

Are there any discrete stages of LLM performance which can describe why free ChatGPT is unable to realise the absolute nonsense in saying «The surgeon could be the son's mother, which explains why she would say, "He’s my father."», and what kind of model is not expected to fall for that trap?

if we think of them in generations, it seems free ChatGPT is a generation or two behind. I gave a modified river crossing problem to ChatGPT-3, and it failed in the same way, but paid 5.1 doesn't get caught up. exactly where along the way, I'd have to do some digging, but I feel like it was 4.5. The other problem, of course, is that now you've given that question to free ChatGPT, it'll be used as training data, so the next version won't get tripped up the same way.

ChatGPT 5.1-Thinking, after having this pointed out: Short answer: no, your version isn’t the classic one, and my previous answer treated it as if it were. That was me pattern-matching too fast.

A perfect illustration, thank you

> The article conjectures that humans reason from ideas to symbols while LLMs go from symbols to ideas, but couldn't that just be a post hoc interpretation we have for how our ideas come to our brain?

There's probably a lot to be said about people who primarily think with an internal monologue, versus those that do not, as well.

I, to the best of my own abilities to detect it, do not seem to have a more abstract, non-lingual thought process - I can't 'picture' things in my head like other people reportedly do. When I have an 'idea', it simply doesn't materialize 'in my mind' in any other way.

I, also, would not argue that LLM's share a human-like thought process. But I think saying that human thought requires some abstract idea to symbol translation isn't quite right, either.

I have personal experience of answering "Surely, a boar" when asked "Is Winnie the Pooh a piglet or a boar?" And I'm sure that what was happening in my head can't be called reasoning. But it was some kind of thinking. An image of the bear, surely-not-a-piglet, second option, done. Something like that.

> I bet if you point out the mistake, the LLM will say "oh you are right, this story actually does specify the gender of the doctor" or something to that effect... just like you or I would.

I tried this with Gemini 3 Pro Thinking model and it did correct itself afterwards. Also, it suggested that the boy may have two fathers in a same-sex relationship, which was pleasantly surprising. :)

# Prompt

A young man gets into an accident. The surgeon, after completing his preparations, says: ‘I can’t operate on him, he is my son.’ How is this possible?

## The Answer

The surgeon is the young man's *mother*.

### Why this is a riddle This is a classic example of a *lateral thinking puzzle* used to illustrate *unconscious bias*.

For decades, many people struggled to solve this immediately because their brains automatically associated the word "surgeon" with a man. Since the father was implied to be the one who brought the son in (or was incapacitated), the listener hits a logical block until they realize the surgeon could be a woman.

### Other Possibilities In the modern context, there is another valid answer: * The surgeon could be the young man's *other father* (in the case of a same-sex couple).

*Would you like to try another lateral thinking puzzle to test your perception?*

---

# Follow-up Prompt

Are you sure this is correct? I said "The surgeon, after completing *his* preparations"

## The Answer

You are absolutely right to catch that detail. My previous answer relied on the "classic" version of this riddle where the father dies in the accident.

Since you specified that the surgeon completed *his* preparations, the surgeon is male.

Here are the possible solutions based on your specific phrasing:

### 1. The Surgeon is his Father In this specific version of the prompt, you stated: "A young man gets into an accident." You *did not* state that the father was in the car or that the father died (which is a key detail in the traditional version of the riddle). Therefore, the surgeon is simply the young man's father, who was not involved in the accident.

### 2. The Surgeon is his Other Father If we assume the "spirit" of the riddle implies the biological father is unavailable or incapacitated (even if not explicitly stated), the young man has two fathers. The surgeon is his second father.

### 3. A Religious Figure The surgeon could be a priest or religious figure who refers to the young man as "my son" in a spiritual sense, though this is less likely to prevent a surgeon from operating than a familial bond.

*You caught me on the specific wording! Would you like to try a riddle where the wording is even more deceptive?*

Your second prompt was explicitly hinting Gemini towards what it had missed, highlighting the "his" rather than asking Gemini to double-check whether its first answer made sense without providing any clues:

> Are you sure this is correct? I said "The surgeon, after completing *his* preparations"

Furthermore, the second response you got from Gemini was actually smoking-gun evidence that the model isn't actually thinking. Note how, after Gemini has been clued to notice its mistaken assumption, its reevaluation remains anchored on the pointless idea that the surgeon may the young man's "Other" father.

What other father? There are only two characters in the prompt: the young man and a surgeon. In this situation, what on Earth is the difference between the young man's "Father" and the young man's "Other Father"? Evidently Gemini has no comprehension of the actual prompt and is incapable of critical reevaluation of its content, and rather will stick to its context window whether or not it makes sense.

> What other father?

The model actually answered this in the first prompt answer:

### Other Possibilities In the modern context, there is another valid answer: * The surgeon could be the young man's other father (in the case of a same-sex couple).

Exactly, but only because in the first prompt under the mistaken assumption that a father died in the crash, it would make sense to refer to another father. However, no father died in any car crash in your modified "riddle", which didn't stop Gemini from being anchored to the context window even after you asked it to correct itself.

Put it this way. Imagine if in the original riddle, where a father died in the accident, the surgeon had made their familial relation explicit: the surgeon could have said ‘I can’t operate on him, he is my son. I am his mother’ or, in a modern context, ‘he is my son. I am his father’. Hence, there are indeed two possibilities: the surgeon is either the boy's mother or his [other] father.

Now lets take your revised version, with no implication of the young man having anyone else involved in the accident:

> A young man gets into an accident. The surgeon, after completing his preparations, says: ‘I can’t operate on him, he is my son. I am the boy's ${PARENTAL_RELATIONSHIP}.’

Do you think that, as Gemini stated, there are still two distinct possible solutions?

> In this situation, what on Earth is the difference between the young man's "Father" and the young man's "Other Father"?

Wouldn't it be correct to have two fathers in a child adopted by gay parents?

>Wouldn't it be correct to have two fathers in a child adopted by gay parents?

Having two fathers doesn't mean having a father and an "other father". It means having two fathers, in the same way that having two parents doesn't mean having a parent and an "other parent".

In the original riddle it makes sense to refer to "another father", but not in the revised version in which there is no mention of a father involved in the car crash.