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What Are the Chances We’ve Been Visited by Aliens?

WASHINGTON, DC - MAY 17: U.S. Deputy Director of Naval Intelligence Scott Bray explains a video of an unidentified aerial phenomena, as he testifies before a House Intelligence Committee subcommittee hearing at the U.S. Capitol on May 17, 2022 in Washington, DC. The committee met to investigate Unidentified Aerial Phenomena, commonly referred to as Unidentified Flying Objects (UFOs). (Photo by Kevin Dietsch/Getty Images)
WASHINGTON, DC - MAY 17: U.S. Deputy Director of Naval Intelligence Scott Bray explains a video of an unidentified aerial phenomena, as he testifies before a House Intelligence Committee subcommittee hearing at the U.S. Capitol on May 17, 2022 in Washington, DC. The committee met to investigate Unidentified Aerial Phenomena, commonly referred to as Unidentified Flying Objects (UFOs). (Photo by Kevin Dietsch/Getty Images) (Photographer: Kevin Dietsch/Getty Images North America)
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The conclusion of the US congressional hearing on UAPs, formerly known as UFOs, is an opportunity to take stock of where matters stand on a question that has captivated humankind for centuries: Have we been visited by aliens or not?

On this question, the hearing was by no means definitive. As unsatisfying as that may be, we did learn a few things — not the least of which is how to sharpen our thinking about this subject.

The first and most important lesson is that many cases of UAPs, which stands for Unidentified Aerial Phenomena, cannot be explained by observer error, at least not in any simple way. There do seem to be vehicles (“phenomena”?) going many times faster than US military craft, stopping and turning on a dime, showing no visible signs of propulsion and operating in ways that appear to violate standard understandings of aerodynamics.

The evidence is from multiple sensor sources, including photography, and supported by numerous eyewitness accounts. The US government is coy on its other sources of sensor measurements, but has stated that the same technology that is detecting UAPs is also used for routine intelligence purposes.

Don’t expect more details anytime soon. Nevertheless, it’s safe to say — and recent conversations with knowledgeable people have led me to believe — that the US government has standard radar and satellite evidence of these phenomena. If these moving vehicles were pure phantoms, not showing up in any other sensor readings, why would the government have held these hearings in the first place? It would have been easier to simply dismiss UAP reports and move on.

There are popular YouTube videos by Mick West, a prominent debunker of pseudoscience, suggesting that Navy videos of UAPs flying at hypersonic speeds reflect human and camera errors. Yet the US military and intelligence sources are not endorsing that hypothesis, even though it could make their lives easier, and so it seems unlikely. (Recall that, several decades ago, experts exposed Yuri Geller’s “magic tricks” rather quickly.)

All this said, there is a hunger for understanding of the UAP phenomenon. The problem is that there isn’t nearly enough evidence to conclude these are spacecraft of alien origin, so a lot of people dismiss these stories altogether.

But the question is not binary. What if we thought about it probabilistically? More specifically: What are the three best reasons to think UAPs might be of alien origin? And what are the three best reasons for thinking this is quite unlikely? At the end I’ll give you my probabilities — and I hope you will think carefully about yours.

The case for alien visits:

1. Alien visitation of earth is to be expected.

Philosophers, astrophysicists and others love to debate what is called “the Drake equation,” which concerns how many advanced alien civilizations are out there. Our galaxy arguably has between 100 billion and 400 billion stars, and we are discovering new potentially habitable planets all the time. Given how advanced human civilization is on earth, you might expect some even more advanced civilizations elsewhere in the galaxy, ones which have the ability to send messages to other solar systems.

Even if you find the prospect of interstellar alien civilizations highly unlikely, there are so many candidate stars and planets that it probably has happened at least once. Those civilizations can simply send out some self-replicating solar- or nuclear-powered drones — no little green men required — and hope some of them end up somewhere interesting.

There is plenty of debate about the right numbers to plug into the Drake equation, and thus the number of potential interstellar civilizations. These debates won’t be settled soon, but at the very least they challenge the presumption that alien visitation should be considered a priori unlikely, counterintuitive or surprising.

For a long time, skeptics of alien visitation had a simple question: “Where are they?” One possible answer is that the aliens already have shown themselves to us, if only in the form of uninhabited drone probes.

2. Alternative explanations do not hold up.

It now seems unlikely that the recordings are picking up secret high-powered experimental craft of the Russian air force. Just ask Ukraine. And given that the Nimitz recording and sighting dates back to 2004, should we really think they are advanced Chinese vehicles? Although the US military has had increasingly frequent interactions and near misses with Chinese military vehicles in the South China Sea, they don’t seem anything like the UAP reports (many of which are based in the Atlantic).

Another common hypothesis has been that the recordings are picking up a secret advanced vehicle from some other hitherto unknown part of the US government. If so, again, why hold these hearings in the first place? If the secret branch has the resources to produce such aircraft, wouldn’t someone have stepped forward by now? Wouldn’t it be at least an active rumor? Or couldn’t someone in the secret operations branch call up a friendly senator or two to get the hearings called off? In fact, last week’s congressional hearing rejected this explanation outright.

It is also hard to believe this is all an elaborate US “psy op” against the Russians or Chinese. For the US to admit so brazenly that it doesn’t know what’s going on in its own backyard hardly seems calculated to scare or intimidate.

3. Some top US leaders seem to think aliens have visited us.

Former CIA director John Brennan raised this possibility when I interviewed him in 2020, while former Presidents Bill Clinton and Barack Obama have noted that alien visitation is a possible cause of the unusual measurements and sightings.

To be clear, Obama and Clinton don’t seem to consider alien visitation as the primary hypothesis. But maybe the US government asked former leaders to make supportive and open-ended public statements about the possibility of aliens, so that it does not look unprepared if and when they show themselves — and Clinton and Obama agreed. And who is supposed to know better than they do?

Not one of these three points is a knockout argument, of course, or close to it. But they keep the alien-contact hypothesis viable. So what about the other side?

The case against visits by aliens:

1. Alien sightings remain relatively rare.

Let’s say alien drone probes can make it here. That would imply the existence of a very advanced civilization that can span great distances and command energy with remarkable efficiency. If that’s the case, why isn’t the sky full of aliens? Why aren’t there sightings from more than just military craft?

So the question is not so much, “Why don’t we see aliens?” as, “Why don’t we see more of them?” It is a perfectly valid (and embarrassing) question. On one hand, the aliens are impressive enough to send craft here. On the other, they seem constrained by scarcity.

Are we humans like those bears filmed in the Richard Attenborough nature programs, worthy of periodic visits from drone cameras but otherwise of little interest? The reality is that bears, and indeed most other animals, see humans quite often.

2. If you believe aliens are real, then you should be prepared to believe that religious miracles are real, too.

Most Americans believe in God, and many millions of them believe in angels and other forms of religious miracles. (For the record, I do not.) I do not know how many Americans who believe in aliens also believe in angels, but I suspect the ratio is lower than it is among the population at large. Yet a belief in alien visitation is just as unusual a hypothesis as a belief in religious miracles. Once we “open up the box” and consider non-scientific explanations for UAPs, such as space aliens, why exactly should we rule out non-secular explanations?

Other commentators have suggested that UAPs come from alternate universes or perhaps even from the future. Those hypotheses to me seem much less likely than simple alien visitation. But on what basis do I make that claim? I have no experience with being right about this phenomenon, and neither does anyone else. In other words, it may be that citing space aliens opens up too many other possibilities.

3. The alien-origin hypothesis relies too much on the “argument from elimination.”

The argument from elimination is a common rhetorical tactic, but it can lead you astray. You start by listing what you think are all the possibilities and rule them out one by one: Not the Russians, not sensor error, and so on — until the only conclusion left is that they are alien visitors. As Arthur Conan Doyle’s Sherlock Holmes once said: “When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth.”

The argument from elimination works fine when there is a fixed set of possibilities, such as the murder suspects on a train. The argument is more dangerous when the menu of options is unclear in the first place. Proponents of the alien origin view spend too much time knocking down other hypotheses and not enough time making the case for the presence of aliens.


There is an argument that is often used against the alien-origin hypothesis, but in fact can be turned either way: If they are alien visitors, why don’t we have better and more definitive forms of evidence? Why is the available video evidence so hard to interpret? Why isn’t there a proverbial “smoking gun” of proof for an alien spacecraft?

This particular counter isn’t entirely convincing. First, the best evidence may be contained in the still-classified materials. Second, the same question can be used against non-alien hypotheses. If the sensor readings were just storms or some other mundane phenomena, surely that would become increasingly obvious over time with better satellite imaging.

The continued, ongoing and indeed intensifying mystery of the sightings seems to militate in favor of a truly unusual explanation. It will favor both the alien-visitation and the religious-miracle hypotheses. If it really were a flock of errant birds, combined with some sensor errors, we would know by now.

So, if we try to approach this question as rational truth-seekers, where do we end up? All the arguments above seem inconclusive. I am still struck by the absence of a good alternative to the alien hypothesis, but am not sure how heavily I should weigh that judgment. A little or a lot?

To cite a favorite forcing question of mine: What if I had to put down a bet?

When all is said and done, I rate the alien-origins hypothesis as at least 10% likely. I see some reasonable chance that the absence of a plausible alternative hypothesis reflects the reality that the alien-origin hypothesis is true. I can’t derive how I get to the exact probability for that option, but it seems to me it ought not to be tiny, given that alien visitation is not a priori so unlikely.

Many of my friends and peers find my judgment crazy and see it as evidence of the decline of my cognitive powers. Perhaps you agree. For myself, I can only say that I don’t think the aliens will see it that way.

More From Bloomberg Opinion:

• We Need a Plan If We Find Out We’re Not Alone: Mark Buchanan

• The UFO Report Won’t Change Minds, But Maybe It Should: Stephen Carter

• If the Pentagon Takes UFOs Seriously, So Should Markets: Tyler Cowen

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Tyler Cowen is a Bloomberg Opinion columnist. A professor of economics at George Mason University, he hosts the Marginal Revolution blog and is coauthor of “Talent: How to Identify Energizers, Creatives and Winners Around the World.”

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