In the year 1647, philosopher René Descartes imagined the possibility of an all-powerful “evil demon” — the deus deceptor — who “employed all his energies in order to deceive me.”

The deus deceptor caused Descartes to perceive a different reality than actually existed, and this concept led him to all sorts of interesting ideas around dealing with doubt. (How can one reason about the world when unsure about your underlying perceptions? If such doubt exists, what can we truly say about the world or ourselves?)

In exploring the concept in his Meditations on First Philosophy, he asks:

How do I know that he has not brought it about that there is no earth, no sky, no extended thing, no shape, no size, no place, while at the same time ensuring that all these things appear to me to exist just as they do now?

What is more, […] may I not similarly go wrong every time I add two and three or count the sides of a square, or in some even simpler matter, if that is imaginable?

So, naturally, I built this idea into a AI-powered Chrome extensionThanks to Kevin Fishner for coming up with the excellent name. It turned out to be more apropos than I could have imagined…. And it turned out to be unexpectedly thought-provoking.

You probably get most of your information about the world through your web browser. The Deus Deceptor™ extensionFAQ: Did I actually trademark this? Answer: No. takes advantage of this and — as Descartes would say — employs all its energies in order to deceive you.

The Deus Deceptor™ extension:

  • looks at every webpage you load
  • if there’s content on that webpage that matches a certain concept the Deus is watching for,
  • it passes that content (and its surroundings) to an AI model, which is tasked with re-writing the content to reflect a different reality
  • and then it seamlessly replaces the original content with the new, altered content, leaving you none the wiser

Let’s look at an example. In this case, the Deus is looking for “Elvis” and has been programmed to believe that Elvis remains alive.

Elvis’ Graceland estate’s website has a perfectly lovely biographical page about him. See below for a screenshot under normal conditions:

But when the extension is turned on, this happens (highlights added afterwards):

Now, listen: I don’t want to deceive you. That would be wrong.

I want to do something far better: give you the tools to deceive yourself.

If you go into the Deus’ configuration options, you’re presented with the opportunity to input “subjects” and “rules.” Whenever you encounter one of those subjects on the web, the Deus will take the surrounding paragraphs and rewrite them according to the corresponding rule.

Here it is on a children’s math worksheet with “highlight” mode enabled, so you can see what changed and hover over it to reveal the original text. Just as Descartes feared, the Deus Deceptor™ can shake even our conviction in simple addition.

Deus Deceptor on math

As another example, I requested that the Deus take everything about “Trump” and rewrite it as if a babbling child said it. Here’s what the front page of the New York Times looked like from the mouth of such a kiddo:

Oops, sorry, that’s the unedited original. Tough to tell sometimes!Ducks. It’s a joke! Anyway, here’s the actual Decepted version:

Imagine some of the wonderful possibilities of using this extension:

You could prevent yourself from ever seeing anything you disagree with, creating a Twitter/X-style “muted words” list but for the entire internet.

You could create a world where the facts of all events are twisted to match your preferences.

You could change all content to perfectly fit your personal outrage profile, so you can be angry all day, every day.

Hm. This all seems like a Very Bad Idea.

It’s a filter bubble on steroids. A way to change things that people truly wrote to things they didn’t. It even literally has the word “Deceptor” in its name!!

And, to be clear, I don’t really think you should use itAmong other issues one might expect from a one-morning hack project, it may pass sensitive information in your browser to the Google Gemini API. I haven’t published it to the Chrome Web Store. You’ll need to manually install it (instructions further down) if you want to try it. (I’m not even sure I could get it on the Chrome Web Store if I tried — they “do not allow products that deceive or mislead users…”).

But:

I think this is going to happen anyway, and — unfortunately — likely less transparently. I built the Deus Deceptor™ to explore this idea and hopefully make a few people think about it.

In the early internet — and before — we made explicit choices about what information sources to consume.

Then, in the aughts, the information we got came from our friends (whom we chose) and our search engines (which we at least specifically queried).

The last decade of information consumption has been driven by the oft-discussed “algorithms” — which have still presented us existing information, but with the innovation of doing so according to our implicitly-derived preferences.

And now, we’re moving to the next era: agents. These agents will present information to us according to our implicitly-derived preferences and they will be presenting information that has been created specifically for us.

I think there’s a good chance that in the next couple years, each of us has a agent that intermediates just about everything that comes our way. Maybe it’s called Apple Intelligence, or ChatGPT, or Claude, or something else. But this agent will be responsible for taking in raw information and crafting and presenting it just for you.

Do I think they will edit people’s words and present them as if the person wrote something they didn’t, the way Deus does?

No. But: they could.

And this is exactly what was causing Descartes heartburn nearly four hundred years ago: what if some all-powerful being — one that sat in between you and the world — could choose to deceive you here and there?

I’d be remiss not to mention: there is also a positive case for the Deus: what if it were configured to defuse AI-generated content that has been created specifically for the purpose of targeting you?

I can imagine a world where the targeted content gets absurdly good and convincing. It’s purpose-built to push all of your personal buttons to get you — yes, precisely you — to buy, vote, whatever.

Maybe then, we’ll all want defensive agents intermediating that — removing it or editing it. Call it a Deus DeCeptor, or something like that.

But either way, we’re entering a strange new world — where content is built to target us individually and then pushed to us individually. And I’m not sure most of us are quite prepared for that.

If you really want to run the Deus, check it out on GithubAgain: I don’t recommend running this. Not only for mind-virus / infohazard / filter bubble reasons, but also because it’s probably insecure and may pass all your personal data found on webpages to Google Gemini.. There’s a README. It’s simple if you’re technically inclined. You’ll just need your own Google Gemini API key (pay for your own damn deception!).

With that said: it has been interesting and, frankly, mind-bending for me to use. It is remarkably (and disappointingly) easy for my brain to go on autopilot and simply default to believing that people actually wrote the edited text under their names.

For instance: I told it to rewrite AI-related content into a caricature of Gen Z language. I opened my X feed and completely forgot, and smiled at some of the bizarre tweets I was seeing. And then I realized: I had been tricked by the Deus Deceptor™.

And now, having lived with this not-just-a-thought-experiment deus deceptor for even a few hours, I can say from experience that Descartes was right to wonder about this.

I told it to make some topics slightly angrier, and some topics slightly happier; I told it to completely rewrite certain topics to say the reverse of every sentence; I told it to amplify the intensity of every opinion on certain people. And I flipped off highlight mode, so I couldn’t tell if a given sentence was transformed or not.

I’ll be honest: it felt out-of-control. This all started as just a proof-of-concept, but became unexpectedly intense.

It’s surreal to read something, react internally to it, and then realize that you aren’t even sure how real it is.

I was the one who built the Deus and I was in control of the ruleset (picking which topics got what treatment). But it still tricked my brain — I could no longer tell what was true, what wasn’t, and what fell somewhere in between. I went through posts and news stories and even emails without any sense of grounding.

And in hindsight, I realized that I was experiencing exactly what Descartes had been talking about when he brought up this extension’s namesake.

A Deus like this creates doubt in your mind.

And for me, at least, it raised doubts about not only the content I was reading when it was on, but also when it was off.

We default to trusting what is put in front of us. But should we?

Maybe there are Deceptors out there already — and perhaps, even without them, the veracity of the information we consume should be viewed the same way.

This all led Descartes, back in the 1600s, to wonder if the only truly undoubtable thing was the act of thinking itself — because even if deceived about everything else, the very act of being deceived requires a thinking subject.

And so his famous “cogito, ergo sum” — “I think, therefore I am” — emerged not as a logical syllogism but as a sort of performative truth: the very act of doubting proves existence.

His deus deceptor and its successor, my Deus Deceptor™, are tools to help us reach those same conclusions. Whether created by a thought experiment or a Chrome extension, doubts have a righteous place in our perception of reality.

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