First, the flavor and framing. You go to sleep as normal, but when you awaken, you find yourself transported to a dark, underground lair, all tunnels and chitinous furnishing, ornamented with distended protuberances and segmented geometries. You glance around for any indication of what’s going on, and then…

Your abductors reveal themselves as changelings who’ve been surveilling you and those around to you for several years. One of the changelings you can see has already copied your face. After all, they have extensive observational data draw on.

Why were they observing you at all? Well, someone near where you live is a changeling, and the collective keeps track of everyone who might be a threat or asset to one of their infiltrators. This, of course, should prompt skepticism. Someone you’ve met is a changeling? Who? How?

But you wouldn’t have noticed. They are very good at what they do. A changeling assigned to assume someone’s role is the most skilled impersonation there is. In prolonged “imitation game” conversations, most people cannot tell if someone close to them has been replaced. Make no mistake, the imitation is not perfect: it is possible to discover discrepancies if you pry hard enough.

This is because changelings are not supernaturally effective at what they do. They are not super‍-​intelligences capable of emulating the entire human psyche as a subroutine of their cognition, and they are not telepathic mind‍-​readers with any deep access to the inner life that motivates and explains their target’s behavior. All they have to go on is behavioral observation, but their predictive understanding of psychology far outstrips modern science.

Now, you can probably guess that the reason the changelings have abducted you is because they wish to assume your likeness and replace you. And no lies are told: they do. However, they are not monsters, and if you don’t want to be replaced with a changeling, they will return you to your bed unharmed. They will be gone as ghosts, and this encounter will seem a nightmare.

Put simply, they seek license to use your likeness.

Okay, but why would you ever want to be replaced with a changeling?

Well, that brings us to why you were abducted. Remember the surveillance? Well you see, analysis of their data has lead them to conclude that you are afflicted a very deadly disease. It’s not infectious, and even with the best treatment modern medicine is capable of, it always kills 99% of patients in circumstances like your own.

(You are surprisingly calm, receiving this dire news; just as calm as you were to hear that there is a group of inhuman mimics replacing people you know, and you never had any privacy from them. Ah, they say, that would be the venom; it sedates panic to promote clear thinking without impairing judgment. You are capable of intellectually recognizing the danger and violation in what they do, but you are left paralyzed and unable to attack or escape the changelings.)

And for all that they were capable of detecting this disease before any doctors could, they do not currently possess any secret means of treating it.

They consider all death to be a tragedy, and your passing will wound those in your life. Wouldn’t it be kinder if there was someone there to offer company and service to your loved ones in your stead? Yes, both sides would benefit from this arrangement.

You see, from a changeling’s perspective, identity is an illusion. The human urge to draw some hard boundary between a person and faithful reprise of that person’s role is a fallacy, a limitation of your consciousness. You would live on in our memory and enactment. You don’t have to die.

But ultimately, the decision is yours. You are presented with two pills.

Take the blue pill, and you return to sleep. You’ll wake up in your bed, all this nonsense about changelings gone like a dream. There’s nothing you need to worry about. Tomorrow, you’ll happen to bump into someone who’ll mention there’s a dangerous new condition that’s been cropping up and suggests you have your doctor screen for it. Your life will proceed as normal and, 99 times out of 100, come to an end shortly thereafter.

Take the red pill, and your body will drift off and never awaken. Your flesh provides a model for the changelings to perfect their imitation, and before the sun rises, an identical form is blinking awake in your body.

The changeling will behave much as you would, but is quite aware that they won’t pass perfectly. They could chose navigate your life in a way that mitigates or provides exonerating pretext for the inevitable discrepancies (contriving an injury, illness, or trauma, perhaps) and will subtly study your relations to improve the imitation.

Or maybe they won’t bother with any of that deception. they are basing their actions on your behavior, after all, so the range of options they have available depends on what would be in‍-​character for you.

Are you uncomfortable with the thought of a mimic lying to everyone you care about? It’s not a rule that they can’t tell anyone. But if you were changeling, would you have told anyone? And if you did, would your friends understand and accept that? (This is the irony: lying is only part of the premise if you’re unable to accept the truth.^note[It is amusingly Newcomb‍-​like[Nuances of Newcomb’s Problem] in that way.])

Another objection‍ ‍‍—‍ what’s most likely to unsettle those discovering an imposter‍ ‍‍—‍ hinges on a misunderstanding of what changelings do. It’s no surprise: humans have no respect nor patience for the long art. Typically, impersonation is a means to an end, a contrivance discarded as soon as it is found out or has exhausted its purpose.

Indeed, one could meaningfully define authenticity as whether something is done for its own sake or simply to advance a scheme. In this way, changelings are highly authentic. No goal attained through such faithful mimicry of your life would not be achieved swifter and with less hassle by more direct means.

When someone is discovered to be an imposter, this is taken as a threat, an omen of some betrayal soon to come. Why else would you bother pretending? But bothering is to their exoneration, not condemnation. They do not put this much effort into a role unless they’d commit indefinitely.

Your changeling shall not grow tired and abandon their role. (Or, equivalently, if they should, a successor shall be trained for a seamless transition.) The expectation that this will falter should be treated as just as likely as your untimely death. (At least before you knew about the disease.)

Regardless of how they live out your life, they have do goals besides always being an imperfect copy of you. Given a choice to act obviously out of character, they’ll chose what’s more faithful, but given a choice to act subtly out of character to advance the changeling agenda, they may diverge.

But what is the changeling agenda? This a thought experiment, not a worldbuilding exercise; the only point of including this detail, rhetorically, is so that the question is fundamentally different from asking, “What if you got replaced with a clone of yourself missing memories?”

The changelings do not want to cause any physical harm or unnecessary distress. Nevertheless, your imposter will use your role and likeness for something you would not want to do. Maybe that means sometimes taking baths in icky slime and eating gross goop, maybe that means sometimes blowing off your friends to go hang out with other changelings instead, maybe it means worshiping the false god at mimic church.

The point is: they are not wholly you, and they cannot be treated as purely a lossy imprint of you.

But are they enough of you that living on through their act is preferable to a 99% chance of oblivion? Which pill would you take?

To recap:

• Blue pill means 99% chance of bodily death, 1% chance of waking up from a bad dream swiftly forgotten.
• Red pill means 100% chance of bodily death, a changeling imposter wakes up in your bed and faithfully replicates your behavior.

Everything should be taken at face value. The changelings are completely correct about your chance of dying soon: it’s no lie or misdirection. The pills do exactly what they’re advertised to do. The changelings will leave you alone if you happen to live.

Of course, there’s a lot to unpack with this question, and since so many people’s reaction to the hypothetical is “What? Why would I ever pick red?”

So here’s a long list of variants and followup questions to consider.

Death rate.

Does the answer change if the chance of surviving after taking the blue pill is lower? One in a million? One in a trillion? Absolute certainty of death? Or higher? 25? 75%?

Purple pill.

Does the answer change if there is a another pill? It’s a medicine that prevents death from disease, but only effective 9% of the time. (And 1% of the time, you wouldn’t have died anyway, for a total 10% survival rate.) However, the purple pill requires valuable resources, and the changelings will only grant it if you agree to be replaced should it fail.

Thus, choosing purple means 10% of the time you live, and 90% of the time you effectively took the red pill. Does this change your answer? Would it change your answer if the percentage was different?

Green pill.

Does the answer change if the changelings also offer a green pill guaranteed to cure your condition, with strange side‍-​effects?

1. You will wake up missing 80% of your memories, a shadow of yourself;

2. you wake up completely amnesiac, but the changelings agree to provide their summary of your life and personality;

3. you wake up with your memories hard reset to what they were ten years ago to the day;

4. you wake up with every memory suppressed; however these “blockers” decay randomly, with a half‍-​life measured in months.

5. you’re found brain dead in your bed, but miraculously recover to a coma state, and emerge months later with moderate and lingering damage to cognition and memory.

Would you pick red, blue, or some shade of green? If you prefer blue to red, do you prefer blue to every version of green? Likewise if you most prefer red.

Heart to heartless.

Does the answer change if you’re granted a long conversation with the imposter first? You can pour your heart out, reveal any secrets you think they’d miss, and you can provide input on how you want them to interact with your loved ones. They will not mislead you. After the conversation, you make your choice.

Is having this conversation alone enough to change your answer, or would you use the conversation to determine if the changeling truly is a worthy successor? Could a clever changeling convince you that they are in fact already you?

Cannibalism.

Does the answer change if the cause of death is different? In this variant, the changelings weren’t surveilling you incidentally: rather, they were waiting for their chance to strike, and they have no intentions to let you live. They only offer the red pill, so you can go out with dignity, but if you refuse, they will attack and kill you anyway. There is a narrow, 1% chance you can find a way out alive. Is it worth the risk?^note[As a historical note, this was (essentially) the original framing.]

Vampirism.

Does the answer change if the changelings explain why they have to replace people? Perhaps they are emotional vampires, draining love or energy from those around them, or perhaps they are outright hematophages: either way, they take, but never enough to cause lasting harm. Or perhaps they’re simply hunted by prejudiced changeling‍-​hunters who’ll torture them unless they find refuge in pseudonyms.

Point is: what if they need your life more than you do?

Selfless‍-​actualization.

Does the answer change if the changeling’s goals are nobler? A changeling has greater executive function, higher emotional intelligence, and a vast hivemind support network. If they are better at living your life than you, why not pass the torch? If they want to make the world a better place, undo the injustices of human society,^note[as is surely faithful to some extrapolation of your character] wouldn’t that have a greater impact than anything you’d otherwise do?

One of the most obvious analyses of this problem is that you’re being asked to chose between a 1% chance of living and a 0% chance of living. The changeling can’t possibly be you, they have none of your first person memories, they were never a part of your continuous chain of consciousness, and thus why should you care how similar they are to you?

I contend this is simplified and sloppy thinking, though I won’t present the complete case for this position in this post. Nevertheless, these next variants exist to complicate this “argument from continuity.”

Guided meditation.

As the red pill takes effect, you and the changeling undergo a focusing exercise, each of you narrowing your attention down to a single point, synchronizing on the same all‍-​enveloping thought. Meditate until all else falls away. So long as you never take your mind off this one image, you won’t even think about your sense of self or whether this thought resides in the changeling’s head or your own.

Do you think this could preserve any continuity?

Hypnotic suggestion.

You are placed under hypnosis and told you imagine your consciousness continuously metamorphosing and sublimating into the changeling’s consciousness. You feel the red pill taking effect, and you visualize it as transporting you into the mind of the changeling. Before the imposter wakes up, they will spend a long time imagining those last moments of yours, so vividly it is as if they were experiencing it, remembering firsthand the experience of that red pill‍-​inducing metamorphosis. (Changelings have exceptional neuroplasticity.)

Do you think this could preserve any continuity?

Pink pill.

You will not receive the red pill right away. Instead, you are repeatedly administered a pink pill, containing a hallucinogen which induces psychedelic effects, such as feelings of profound oneness. Over the course of days if not weeks, you are repeated walked through the above meditation exercises and hypnotic suggestions, molding your mind into one that can mirror a changeling’s inner image of you.

Do you think this could preserve any continuity?

Backseat impersonation.

You don’t die instantly. For some time, you will remain in the changelings’ lair, able to track a live feed of the imposter’s activity. You can provide constructive feedback whenever the imposter does something you wouldn’t. You’ll also have regular conversations with the imposter, playing “guess what I’m thinking” games, partly to give them a better model of your inner life, but also just to build rapport. They sympathetically explain what they’re thinking and urge you to identify with them and live vicariously through them.

When there is little left for you to add, you agree to take the red pill and die. (You also die if the changelings discern you aren’t acting in good faith, providing flawed feedback, clinging to survival, etc..)

Do you think this could preserve any continuity?

These last three are fundamentally different questions, so I include them mostly for fun.

Brain scanning.

The changelings place you into a neural imaging device, and your brain activity is continuously read out. the imposter studies the output, and actively tries synchronizing their mental model of you to match. Which is to say, we slightly relax the “no super‍-​intelligence” and “no mind‍-​reading” rules of the experiment.

Does this change the answer change? Would it change if it goes from “slightly” to “moderately” or “completely?” (i.e. what if the changeling are actually robotic replicants emulating uploaded brains?)^note[If you would say “a copy of me isn’t me,” I can only refer you to an older post: Identity is Communication.]

Transformation.

The red pill doesn’t kill you, it turns you into one of them. The change can be dramatic ‍-​ you will discard many your past attachments, interests, personality, either forgotten in profound reshaping of your mind or simply from the alien change of preference ‍-​ but this will save you from dying. And, take it from them: life’s much better as a changeling anyway.

Twist reveal.

You never saw an imposter wearing your face. The red pill won’t kill you; no, it will awaken you. The changelings tell you that you already are one of them, having been assigned to a role deep under cover, either for your protection or an inscrutable machination. But now, unfortunately, the seal on your true nature is breaking down, and your sisters want you back. Take the red pill, and your true memories will return, and they’ll show you how deep the rabbit hole goes. Or take the blue pill, and wither away as a husk.

You don’t know whether they are telling the truth, or this is yet another rhetorical game.