The SETI Paradox

Historically, the Search for Extraterrestrial Intelligence (SETI) has taken place between two rather bizarre guardrails: first, an almost religious faith that life must be abundant throughout our universe (lest we be thought of as special) and second, a superstitious expectation that any such life will closely resemble life on Earth. 

A toxic cocktail by any mixologist’s standards! Where did we get such strange ideas? Surprisingly, these seemingly contradictory assumptions spring from the same shared fallacy: the myopia of the familiar.

The argument for a ‘biotic universe’ is based on the observation that life evolved on Earth, i.e. on one planet (out of 10?) in one solar system (out of 100 billion in the Milky Way alone) in one galaxy (out of 100 billion in the observable universe). 

We couple this with an infamous maxim of illogic called the Why Me Principle. More technically known as the Scandal of Particularity, it is a refusal  to accept the notion that we could somehow be special, much less unique. 

But this ignores the obvious. We are special, not because there is anything special about us, but simply because we’re the ones making the observation. In that sense everything is special in the sense that it is unique. Known as the Anthropic Principle, this maxim holds that ‘somebody had to do it so it might just as well have been us’. 

Recap: We exist. We know that we exist. Others may exist but we don’t know that. All we know is that we exist and, as far as we know, only we know that we exist. But we refuse to allow for the possibility that we might be special or unique. Therefore, we conclude that there must be life elsewhere.

I am looking at the reverse side of a deck of playing cards. I draw one card. It’s the Ace of Spades. It is possible that this is the only Ace in the entire deck; it is also possible that every card is an Ace of Spades. A sample of one tells us nothing about the probability of two, absent other assumptions. Still, we make a fetish of what we know at the expense of what we don’t.

A friend of mine is fond of saying, “All people think thus and so” or “all men feel like this”. Of course, he is simply describing his own thoughts and feelings. He is a chronic victim of ontological myopia. 

The same pathology leads us to the further assumption that all of this abundant inter-galactic life must be more or less exactly like life on Earth. As a result, we are searching the cosmos for carbon based life forms with cellular architecture, governed by a self-replicating mega-molecule (like DNA), breathing oxygen (or carbon dioxide), immersed in water, and behaving intelligently…at least sometimes.

Talk about a lack of imagination! We have set up a diabolical chain of reasoning:

• There is life on Earth.

• We are not special or unique.

• Therefore, there must be life elsewhere in the universe.

• And if something has happened more than once it has probably happened more than twice.  

• Life is life and therefore all life is like life on Earth.

• Therefore, ‘life like ours’ must be abundant in the universe!

  
  

We have balanced the self-deprecation inherent in the ‘Scandal of Particularity’ with an overdose of hubris. On 6/18/2025, Mark Thompson, making a similar observation, wrote in Universe Today: 

“Scientists are revolutionizing the search for extraterrestrial (ET) life by challenging our somewhat Earth-centric assumptions about where and how life might exist in the universe. A new review argues that we must embrace the remarkable diversity of exoplanets discovered over the past two decades and consider a much broader range of environments that could potentially host life…”

The assumption that all life is like ours ignores the role environment plays in evolution. There’s no reason, for example, to assume that life forms will be less varied than their climates. That said, with 10^22 stars, each with an unspecified number of planets and moons, we should expect variations that will test our imaginations. So, we should anticipate a similar diversity among life forms…but we don’t.

Take Earth, for example. As far as we know, all life evolved from a single primordial DNA molecule. From that one, very specific cell incredible biodiversity has evolved. Life inhabits almost every nook and cranny of land, sea, and sky. We find life on mountain tops and in ocean trenches, in the artic regions and in the mouths of active volcanoes. We breath oxygen, I mean CO₂, I mean methane. If ‘God’ makes it, someone will breathe it.

Imagine what evolution might do on a planet like Venus, or a moon like Europa. Or in a galaxy far far away.

Check it out: how different is a sponge from a mushroom, a velociraptor, a Quaking Aspen, or an orca?

Expect orders of magnitude more diversity in the universe! If, and that’s a huge ‘if’, there’s anything out there at all, what makes us think that we’ll even recognize the ET forms we do encounter as alive.

Let’s listen to Thompson: “The traditional focus on finding ‘Earth twins’ orbiting Sun-like stars may be too narrow, given…the incredible variety of planetary environments that exist.

“The research highlights how adaptable life on Earth really is. Bacteria can survive and thrive in atmospheres rich in gases like hydrogen, helium, carbon dioxide, and carbon monoxide, conditions once thought hostile to life. These extremophiles, organisms that flourish in physically or chemically extreme conditions, demonstrate that life's requirements may be far more flexible than previously assumed.

“Perhaps most intriguingly…life might exist without any solid ground beneath it. In so-called ‘cloud biospheres’, life could potentially float in the atmospheres of planets where rocky surfaces are too hot to support traditional life forms. These aerial ecosystems might exist in the thick atmospheres of super Earths, in the cloud layers of gas giants…

“The researchers also consider life in alternative solvents beyond water, and in hypothetical planetary global oceans where entire worlds are covered in (a non-aqueous) liquid (e.g. methane). 

“The shift represents a fundamental change in astrobiology from asking ‘Is this planet like Earth?’ to ‘Could this planet support any form of life we can imagine?’’ 

Any form of life we can imagine – Ah, there’s the rub: how much are we capable of imagining? How much will we let ourselves believe is possible? I suggest putting together a team of 2 – 5 years-olds to help us imagine what ET life forms must look and act like.

“With thousands of known exoplanets showcasing remarkable diversity in mass, size, and orbits, this broader approach significantly expands our chances of detecting life beyond Earth.”

No it doesn’t! First, the probability of our detecting ET life is entirely dependent on the existence of that life. Second, it is unlikely that any ET life form will resemble life on Earth. Third, if there is ET life and we do encounter it, there’s no guarantee we’ll know it when we see it.

“As we stand on the brink of potentially discovering biosignatures in alien atmospheres, embracing this diversity may be the key to finally finding life in forms we never expected, in places we never thought to look.”

Like Alice, we have been searching for our own reflection…we may find something unexpected on the other side of the glass. It may be as unlike our world as the Red Queen’s is unlike Alice’s; but it is just as likely that we will find that there is nothing there at all…once we too have traveled Through the Lookingglass.   

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The Ambassadors, Hans Holbein the Younger, 1533, National Gallery, London. The painting illustrates how the familiar and the measurable coexist with the unexpected and unrecognizable, echoing the SETI Paradox’s challenge to assumptions about extraterrestrial life.