I put this in front of student leaders this summer and it produced the best discussion of the day, because there is no comfortable answer and they could tell.
Neuralink is implanting chips in human brains. Not in a lab someday. Now. Paralyzed patients are moving a cursor and typing using only their thoughts.
Then I gave them four cases and asked where the line is.
Restore movement to the paralyzed? Restore sight to the blind? Upgrade memory for a healthy person? An AI assistant inside your head?
Almost everyone says yes to the first. Almost everyone hesitates by the third. Nobody can explain precisely why, and that inability is the interesting part.
Restoring versus enhancing
The instinct most people reach for is that restoring is fine and enhancing is different.
Giving sight back to someone who lost it returns them to a baseline. Giving someone memory beyond what any human has had is something else.
I think that instinct is pointing at something real. I also think it doesn't survive much pressure.
Glasses enhance. Vaccines enhance. Caffeine enhances, and so does every education you have ever received. We have been augmenting human capability with technology since fire, and almost nobody objects to any of it.
So "enhancement is different" cannot be the whole answer, because we do it constantly and call it progress.
What might actually be doing the work
A few candidates, none of which I hold with certainty.
Reversibility. You can take off glasses. You cannot un-implant a device woven into tissue without consequence. Permanence raises the stakes on getting it right, and we are historically bad at knowing which decisions are permanent when we make them.
Who is choosing. An adult choosing a device for themselves is one thing. A parent choosing for a child is another. An employer where the choice is technically optional but practically required is a third, and that third one is where I get most uneasy, because that is how choice erodes without anyone banning anything.
What happens to the people who decline. This is the one I find most persuasive and least discussed. If enough people enhance, declining stops being neutral. The cost of remaining unmodified rises until it's not really a choice. That isn't a hypothetical mechanism, it's how every workplace technology has gone, just with lower stakes.
Whether it changes the person or their circumstances. Restoring sight gives someone back access to the world. An assistant inside your head changes how you think, which is closer to changing who you are. I don't know how to make that precise. I notice that it feels different, and I notice that "it feels different" has a poor track record as an ethical argument.
Why "we will figure it out later" fails here
The usual pattern with technology is that we deploy, observe harm, and regulate afterward. Slow, expensive, and mostly it works.
It works because the harms are reversible. You can ban a chemical. You can regulate an industry. People are damaged in the interim, which is bad, and then it gets fixed.
Neurological implants in a generation of people is not obviously in that category. If we get it wrong, "we will course-correct" may not be available in the way it usually is.
Which means the asking has to happen before, not after. And before is now, while the answer is still genuinely open and while the people who will live with it are still in high school.
I do not have the answer
I want to be honest about that rather than perform certainty.
I know that restoring function to people who have lost it's good, and I wouldn't want any hesitation about the rest to slow that down. Real people are getting real capability back and that's unambiguously worth doing.
I know that I'm uneasy about optional-in-theory enhancement for healthy people, and that my unease isn't yet an argument.
And I know that the deciding will not happen in a room where anyone asked. It will happen the way these things always happen: incrementally, commercially, one reasonable step at a time, until we are somewhere nobody chose.
The only counterweight I know of is people forming views early and holding them out loud. Which is why I put it in front of seventeen-year-olds, who will be living in the answer long after the rest of us have stopped arguing about it.
Where is your line, and can you say why?