The search for extraterrestrial life – answering Fr Dwight Longenecker

Over on the Inside Catholic website, Fr Dwight Longenecker wrote an article called “Astrophysics and Metaphysics.” The real gist of the article is to say that the search for extraterrestrial life has captured the imagination of both scientists and popular culture, while many people forget that there is plenty of intelligent non-human life that people ignore: the angels and demons. He argues that we should worry first – and more – about understanding the spiritual realm. He has a good point there; our salvation doesn’t depend on the existence of life on other planets, whereas our interaction with beings of the spirit can help or hinder our eternal happiness.

While I understand and appreciate the point that Fr Longenecker is trying to make, he doesn’t make it very well. This is reflected in the comments on his article, and I’m afraid I have to join the chorus of critics on this one. He really seems to have misunderstood the search for extraterrestrial life. I think this is unfortunately common among average Catholics, so I’d like to weigh in on what he says. If you are interested, though, you should read his article before reading what I write below.


He seems to think that astrophysicists assert that size equals importance, and that this argues for extraterrestrial life. That is simply not the reasoning they follow. People who research the possibility of extraterrestrial life (astrobiologists, more than astrophysicists) simply do the math: the more stars there are, the more chances of habitable planets orbiting those stars, and hence of extraterrestrial life. The universe may be vast and uninhabitable, but it might not. (To revisit Fr Longenecker’s example, the Sahara is a bad place for human beings to live, but there IS in fact life in the deserts of Earth, and at least bacterial life even in the most severe environments – such critters being called “extremophiles”.) So size doesn’t indicate importance, but if one assumes that the appearance of life has something to do with statistics and natural processes (which is a different debate), the size of the universe (and hence the number of stars and planets) does count. So much for the first fallacy.

What he calls the second fallacy, what he calls “anthrocentrism” (actually, the term is anthropocentrism), – saying that scientists are assuming that life on other planets will be like life as we know it – is not an accurate portrayal either, for two reasons.

First, scientists are aware that life could be radically different from what we can imagine. However, we only have the tools to search for things that we can imagine, so we use what we have, on the chance that life might be detectable with such tools. Scientists are well aware of this kind of limitation. It’s an example of what is called an “observer selection effect” – the results of any study or observation are limited by the observer’s tools and theoretical structure.

Secondly, even if we make the assumption that life will be like what we know, it might not be a fallacy. There are evolutionary biologists who point to what is called convergent evolution – the fact that, given similar environments, life tends to take on very similar morphologies, even if using very different internal structures. On an elemental level, for example, many different organisms have eyes or similar light-sensitive structures, but they can have very different structures and biological origins. Going to examples on a more larger scale, there are some moths that live in environments analogous to those where hummingbirds live, and they look and act like hummingbirds. There are fossils of two very similar “saber-toothed tigers”, from similar prehistoric ecosystems – but one was related to modern felines, and the other to marsupials. This phenomenon seems to be due to the fact that in certain environments and ecosystems, certain morphologies work well. So, if there is an Earth-like planet with life on it somewhere, may be a good chance that life forms there are morphologically similar to what we see here; things living in liquid may well look similar to aquatic organisms on Earth in similar niches. So much for the second fallacy.

Thirdly, looking for extraterrestrial life has nothing intrinsically to do with materialism. Astrobiologists are not necessarily denying that there is immaterial life – but the fact is, there could hypothetically be other material life forms, and that could be worth looking into!

I’m not saying that there is life on other planets; as Fr Longenecker rightly points out, there is hot debate on that topic among the scientific experts. For instance, the book The Anthropic Cosmological Principle by Barrow and Tipler argues extensively on scientific grounds that we are probably the only intelligent life in the universe right now. Other authors like Max Tegmark argue that there is an infinite number of actually inhabited planets in the “multiverse”. There are things to criticize in the philosophy and theology of these and other authors on the topic, but Fr Longenecker apparently has not studied the subject in depth. That severely weakens his article.


About Matthew Green

I am a translator, origami artist/teacher, and photographer, a blogger, former philosophy professor, and I love to sing. You can see my photos on Flickr and buy prints of some of them on Fine Art America. You can find me on Instagram, Twitter (@mehjg), and in various and sundry other social media sites on the web.
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2 Responses to The search for extraterrestrial life – answering Fr Dwight Longenecker

  1. Convergent evolution is freaky… look at the skulls of a thylacine (“Tasmanian wolf”,
    “Tasmanian tiger”) and true wolf side-by-side… the average person would think they were 2 skulls from the same animal.

    Or the way ichthyosaurs look a lot like dolphins look kind of like sharks… the limitations of fast swimming require a pretty constrained shape. (Though some of this is still the expression of a common vertebrate ‘toolkit’ — though on the other hand, squids still have a torpedo-shaped body with ‘fins’, so the convergence is still there, just more distant.)

    And the sabertooths! In fact, sabertooth cat forms appeared more than twice — at *least* three times (machairodontine cats like Smilodon, the traditional ‘saber-toothed tiger’; nimravid/barbourofelid sabertooths; marsupial sabertooths like Thylacosmilus). And nimravids and barbourofelids probably evolved *their* sabertooth characteristics independently, bringing us to four. And then there are the sabertooth creodonts like Machaeroides… and the modern clouded leopard Neofelis (its upper canines are actually comparable in length, proportional to its size, to the less extreme — eg not Smilodon — prehistoric sabertooths — it’s just a pretty small animal, so less impressive).

    Sorry, bio major, and this is one of my favorite phenomena… it’s endlessly interesting.

    • Thanks for contributing! I’m not an expert on the topic, but I agree that it’s fascinating and amazing. Most of my knowledge about convergent evolution is from a lecture I attended two years ago at a conference on evolution, theology and philosophy, at the Gregorian University in Rome. So at this point, I’m a little sketchy on details, which makes your well-informed comment very apropos.

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