With the increasing complexity of reCAPTCHA, I wondered about the existence of some problem, that only a human will ever be able to solve (or that AI won't be able to solve as long as it doesn't reproduce exactly the human brain).

For instance, the distorted text used to be only possible to solve by humans. Although...

The computer now got the [distorted text] test right 99.8%, even in the most challenging situations.

It seems also obvious that the distorted text can't be used for real human detection anymore.

I'd also like to know whether an algorithm can be employed for the creation of such a problem (as for the distorted text), or if the originality of a human brain is necessarily needed.


2 Answers 2


Informally, AI-complete problems are the most difficult problems for an AI. The concept is not mathematically defined yet, as e.g. NP-complete problems. However, intuitively, these are the problems that require a human-level or general intelligence to be solved.

Real natural language understanding is believed to be an AI-complete problem (this is also discussed in the paper Making AI Meaningful Again by Jobst Landgrebe and Barry Smith, 2019). There are a lot more AI-complete problems. For example, problems that involve emotions.

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – nbro
    Commented Dec 7, 2020 at 14:30

This is more of a comment and philosophical opinion, but I don’t believe that there are any problems an AI couldn’t solve, that a human can. Being new to this forum, I cannot make it a comment on the question (and it would probably be too long) — I preemptively ask for your forgiveness.

AI Eventually Will Mimic Humans (and surpass them)

Humans by nature are logical. Logic is learned or hardwired, and influenced by observation and chemical impulses.

As long as an AI can be trained to act like a human, it will be able to act like one. Currently, those behaviors are limited to technology (space, connections, etc), which the human brain has been optimized to rule out or disregard certain “fluff” automatically enabling it certain super capabilities. For instance, not everything seen is registered through the brain; often, the brain performs differential comparisons and updates for changes to reduce processing time and energy. It will only be a matter of time before AI can also be programmed to behave this way, or technological advancements will allow it to not need some of this function, which will allow it to leapfrog humans.

In the current state, we recognize humans are sometimes irrational or inconsistent. In those cases, AI could mimic human limitations with configured randomization patterns, but again, there really won’t be a need since it can be programmed and learn those patterns automatically (if necessary).

It all comes down to consumption of data, retention of information, and learned corrections. So, there is no problem that a human can perform (to my knowledge) that AI couldn’t theoretically ever perform. Even in the case of chemistry. As we are manufacturing foods and organs, an AI could also, theoretically, one day reproduce and survive via biological functions.

Instead of the question being binary about human capability vs that of artificial intelligence, I’d be more interested to see what people think are the more challenging things humans can do, which will take AI time to accomplish.

  • $\begingroup$ "Humans by nature are logical" -- and when when they are not (which is quite often actually), it is quite easy for AI to emulate that human illogical behaviors too. $\endgroup$ Commented Mar 22, 2023 at 12:48

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