The Shrinking Habitable Zone

Otis Graf is a member of Reasons to Believe’s Apologetics Community.  He recently posted a message which deserves to be known to everyone.

I have written often about “the fine-tuning of the universe” (see joshualetter/blog, “The Existence of God – Four Philosophical Arguments, June 28, 2018 post, chapter II).  Otis presents yet more evidence that our hospitable planet could not have occurred anywhere in the universe by chance, not even once.  Here is Otis’ message, with almost no editing.

A team of five scientists from NASA and several universities has, for the first time, shown that most exoplanets that were thought to be potentially habitable are, in fact, toxic to complex life.  Here, “complex” means oxygen-dependent multicellular life.

Here is the popular article which is a news release from Univ. California Riverside: “New study dramatically narrows the search for advanced life in the universe.  Toxic gases limit the types of life we could find on habitable worlds.”  Here is the paper that was published in the Astrophysical Journal.  “A Limited Habitable Zone for Complex Life

It turns out that for Sun-like stars, most of the “traditional habitable zone” [where water can exist in liquid form] is ruled out because those regions require poisonous concentrations of CO2 in order to remain warm enough to host liquid surface water.  The smaller M dwarf stars will produce atmospheres of toxic carbon monoxide.

The search for intelligent life (SETI) takes a particularly hard hit from this research.  This is a conclusion from the published paper:

One implication is that we may not expect to find remotely detectable signs of intelligent life (“technosignatures”) on planets orbiting late M dwarfs or on potentially habitable planets near the outer edge of their HZs. These CO2 and CO limits should be considered in future targeted SETI searches.

The paper’s authors even invoke anthropic reasoning: “More broadly, limitations on complex life by CO2 and CO may partially address why we find ourselves near the inner edge of the HZ of a G-dwarf star rather than near the center or toward the outer edge of the HZ around one of the much more numerous M-dwarf stars.”

In the UC news release, the lead author of the paper is quoted as saying this:

I think showing how rare and special our planet is only enhances the case for protecting it.  As far as we know, Earth is the only planet in the universe that can sustain human life.

That sums it up.  Earth really is an Improbable Planet.

Otis Graf

Houston, TX

And remember: there are not one but eleven known habitable zones.  For advanced life to be possible, its planet must be in all eleven HZ’s at the same time and must remain there for a long, long time. See



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Christopher Hitchens on God’s Wastefulness

In his April 2009 debate with William Lane Craig (, Christopher Hitchens presented a long string of arguments which I regard as irrelevant to the question which those gentlemen were actually debating, which is whether or not God exists.  In this post I’ll discuss one example.  Following is a close paraphrase of what Hitchens said.

You are free to believe that this creator put himself to the trouble of creating all these species, 99.9% of all of which have become extinct – as we nearly did ourselves.

We are supposed to believe that all this mass extinction and death is the will of God – all done with us in view.  That’s solipsism.  [Solipsism: 1. The theory that only the self exists or can be proved to exist; or 2. Preoccupation with and indulgence of one’s feelings, desires, etc.; egoistic self-absorption.  (]

The wastefulness, cruelty, and incompetence of it!  It doesn’t work for him.  Believe it if you can or if you like.

We’ve heard this argument before, from Darwin himself and ever since, so the question may deserve some consideration.

The existence of waste in nature is irrelevant to God’s existence or non-existence.  The question for debate was not whether a wasteful creator exists, but any creator.  Supposing, for the sake of the argument, that what Hitchens sees as waste is indeed waste, if the waste itself could not exist without God, then the fact of waste in nature would not diminish by one iota the probability that God exists.

And that is our case.  Given that anything at all exists – say, the universe, for example, with all its waste – then an eternal cause of the universe must also exist necessarily; for otherwise one must posit either an eternal universe (which we know is not the case), a universe that caused itself to exist (which is absurd), a universe which came into existence without a cause (which is implausible), or an infinite regress of prior finite causes (which is absurd).

Those four alternatives to theism are exhaustive: there are no other alternatives.  All of them being clearly false, theism must therefore be true – despite waste in nature (if that’s what it is).

Besides, as Craig points out elsewhere, a lack of economy would not be the same for a being who has infinite resources as it might be for Mr. Hitchens.

Finally, if God exists and was wasteful and Mr. Hitchens doesn’t understand why, then the fault is probably with Mr. Hitchens’ understanding and not with God, because, well, He’s God!  If He exists, He can be profligate if He wants to!


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Fuzale Rana of Reasons to Believe offers A Response to the Most Compelling Evidence for Biological Evolution


Fuzale Rana is a biochemist with Reasons to Believe.  This video is an excellent example of the outstanding work which this organization has been doing for over 30 years now.

Dr. Rana opens by describing the recent discovery that the duckbill platypus may hold the key to the treatment of type-2 diabetes in humans.  The male platypus has a venom in its hind feet which contains a hormone that causes its attackers’ blood sugar to crash, causing the attacker to become lethargic.  The hormone is similar to one in humans which also regulates blood sugar, but which is not as long-lasting.  By studying the hormone, scientists may be able to devise a treatment for type-2 diabetes, which is characterized by dangerously high levels of blood sugar.

Evolutionists insist that similar structures in various species must be interpreted within an evolutionary framework as evidence of common ancestry.  Indeed, they cite such similarities (which they call “homologies”) as the most compelling evidence for evolution.  Rana explains how such similarities make more sense within a design framework.

Why would a creator employ common designs?

Homologies make the biological realm intelligible.  If the body structure of every species were fundamentally different, studying one species would offer us no insight as to the functioning of any other species.  Biology as a discipline would be nearly impossible.  The similarity of life-forms enables us to comprehend life generally.  This, in turn, enables us not only to devise treatments for human illness by studying other species, but also to fulfill the divine command to be stewards and caretakers of the planet.

There is more!  Budget 40 minutes for Dr. Rana’s remarks, but don’t miss the Q and A.  Enjoy!




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Professor, Was Jesus Really Born to a Virgin?

New York Times columnist Nicholas Kristoff interviews William Lane Craig of Talbot School of Theology and Houston Baptist University, asking about Jesus’ miraculous conception and birth.  The interview was published in the Times on December 21, 2018.  Click here.  Enjoy!

Click here to read Dr. Craig’s replies to detractors commenting on the interview.  Very much worth reading!  Happy New Year!




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Lennox on Divine Aseity and the Trinity

John Lennox is another of my favorite Christian apologists.  He is Emeritus Professor of Mathematics at the University of Oxford and an Emeritus Fellow in Mathematics and Philosophy of Science at Green Templeton College, Oxford University.

In this 2011 film clip (, which is just over 10 minutes long, Dr. Lennox discusses the question, If God created the universe, then who created God? and the question, How can God be a triunity?

Lennox tells of an occasion on which he addressed a convention of scientists.  Afterward, a member of the audience approached him and asked whether it was possible that Lennox should actually subscribe to such an irrational doctrine as that of the Trinity.  Instead of answering immediately, Lennox asked him a question of his own.

Do you believe in consciousness?  Energy?  (Yes.)  Do you know what they are?  (No.)  Should I write you off as an intellectual for believing in something you don’t understand?  (No.)  That’s what you were going to do to me five minutes ago.  Why do you believe in them?  (Lennox supplies the answer:) Because of their explanatory power.  A trinity is the only explanation that makes sense of the evidence as Lennox sees it.  God Himself is a fellowship.

What is it that a divine fellowship explains?  Many things, I’m sure; but perhaps principally it answers the question, How can God be love, if in eternity past, prior to creation, there was no one around for Him to love?  The doctrine of the Trinity explains that God has never been alone, but that each Person of the Trinity has eternally been in the most intimate fellowship with the other two Persons.  Thus, the doctrine of the Trinity explains how it is that God is love.

Do yourself a favor and introduce yourself to this wonderful man.  For further reading, see God’s Undertaker: Has Science Buried God? (Lion 2009) and God and Stephen Hawking: Whose Design is it Anyway? (Lion 2011).

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Friendship with Jesus

This is worth sharing, I thought, as an example of the often excellent material published by First Things Magazine, a journal of religion and public affairs:

Everyone wants to live with an undivided heart; an undivided heart is one that loves with integrity; chastity is  the integrity of love, whether it is lived in marriage, celibate consecrated life, celibate ordained ministry, or chaste single life; friendship with Jesus Christ, the incarnation of radical love lived in integrity, is the sure path to living chastely in a world that celebrates unchastity.

Excerpt, Xavier Rynne II (pseudonym), Letters from the Synod 2018 #17, First Things Magazine 10.25.18,





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The Existence of God: A Concise Summary

Since publishing my essay on the existence of God, I have wanted to provide a concise summary of the argument.

Why do I do this?  It is because when I see the trees and the stars, realizing the transcendent genius which was required in order to create them, I hear a voice saying to me, “I love you.”

The classic cosmological argument for the existence of God rests on the premise that whatever begins to exist – that is to say, anything which is not past-infinite, anything which is not eternal – must have a cause for its existence.  But even before one considers whether or not to accept that premise, it is useful to observe that there are really only four possible scenarios for the origin of the universe.  This can be clearly seen from the following set of necessary propositions.

Either the universe had a beginning, or it didn’t.

If the universe had a beginning, then either it had a cause or it did not have a cause.

If the universe did have a cause, its cause likewise either had a beginning, or it didn’t.

Those three binary possibilities are exhaustive; that is, there are no other possibilities.  This leads to four possible origin scenarios.

  1. Possible scenario #1.: The universe did not have a beginning; that is, it has always existed.

Modern science has shown this simply not to be the case.  There is a scientific consensus, based on extensive observation, that the universe had a beginning approximately 13.8 billion years ago.

  1. Possible scenario #2.: The universe had a beginning, and it popped into existence out of nothing, uncaused.

This is not logically impossible, but it is implausible because it violates the principles of causation, which affirm that nothing happens without a cause.[1]

  1. Possible scenario #3.: The universe had a beginning, and it was caused by some separate entity which itself also had a beginning.

This too is logically possible, but it entails an infinite regress of non-eternal causes, since one must then ask, what caused the cause, and then, what caused that cause, etc., etc.  If the regression is infinite then it begs the question: how did the regression begin if it did not begin with an eternal cause?  The only way for the regression not to be infinite is for it to come sooner or later to a cause which had no beginning, which is equivalent to the fourth scenario.

  1. Possible scenario #4.: The universe had a beginning, and it was caused by some separate entity which did not itself have a beginning – that is, the cause of the universe was some eternal entity. This is one step from theism. Theism does not entail any of the difficulties inherent in the other possibilities: it has not been falsified empirically, it does not violate the principles of causation, and it does not beg the question.  Thus, theism is truly the only plausible explanation for the existence of the universe.

Scientists believe that all matter and energy, along with space and time themselves, came into existence about 13.8 billion years ago.  If so, and if the universe had a cause, then the cause must have been immaterial, timeless, and immensely powerful.  The Fine-Tuning of the universe shows that the cause was a conscious, purposive Agent of incomprehensible intelligence.  These are some of the attributes which science shows the Creator possesses, to a virtual certainty, and now we have come all the way to theism.  God exists.

There is another basis for concluding that the Creator is a personal entity.  If that were not the case – if the cause of the universe were some physical state of affairs existing from eternity past, then all of the conditions needed for the universe to come into existence would themselves have existed from eternity past; and if so, then there would have been nothing to prevent those conditions from producing the universe at some time in the infinite past.  And if that had occurred, then because of the Second Law of Thermodynamics, which states that in a closed system entropy (disorganization) always increases with time, the universe would already have reached heat death.  It has not done so; therefore, the cause of the universe could not have been a purely physical state of affairs existing from eternity past.

[1] This is the first premise of the cosmological argument.  For a more complete analysis of this premise, see, June 28, 2018, page 11.

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Neuroscience and Free Will

Neuroscience provides strong evidence for the reality of free will.  (Read more.)

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The Author of the Gospel of Luke is “a historian of the first rank”

[The following is an excerpt from “The Evidence for Jesus,” by William Lane Craig (  (Citations deleted).]

The Gospel writers have a proven track record of historical reliability. . . .  I only have time to look at one example: Luke. Luke was the author of a two-part work: the Gospel of Luke and the Acts of the Apostles.  These are really one work and are separated in our Bibles only because the church grouped the gospels together in the New Testament.  Luke is the gospel writer who writes most self-consciously as an historian.  In the preface to this work he writes:

Inasmuch as many have undertaken to compile a narrative of the things which have been accomplished among us, just as they were delivered to us by those who from the beginning were eyewitnesses and ministers of the word, it seemed good to me also, having followed all things closely for some time past, to write an orderly account for you, most excellent Theophilus, that you may know the truth concerning the things of which you have been informed. (Lk. 1.1-4)

This preface is written in classical Greek terminology such as was used by Greek historians; after this Luke switches to a more common Greek.  But he has put his reader on alert that he can write, should he wish to, like the learned historian.  He speaks of his lengthy investigation of the story he’s about to tell and assures us that it is based on eyewitness information and is accordingly the truth.

Now who was this author we call Luke?  He was clearly not an eyewitness to Jesus’s life.  But we discover an important fact about him from the book of Acts.  Beginning in the sixteenth chapter of Acts, when Paul reaches Troas in modern-day Turkey, the author suddenly starts using the first-person plural: “we set sail from Troas to Samothrace,” “we remained in Philippi some days,” “as we were going to the place of prayer,” etc.  The most obvious explanation is that the author had joined Paul on his evangelistic tour of the Mediterranean cities.  In chapter 21 he accompanies Paul back to Palestine and finally to Jerusalem.  What this means is that the author of Luke-Acts was in fact in first hand contact with the eyewitnesses of Jesus’s life and ministry in Jerusalem. . . .

Was the author reliable in getting the facts straight?  The book of Acts enables us to answer that question decisively.  The book of Acts overlaps significantly with secular history of the ancient world, and the historical accuracy of Acts is indisputable.  This has recently been demonstrated anew by Colin Hemer, a classical scholar who turned to New Testament studies, in his book The Book of Acts in the Setting of Hellenistic History (1990).  Hemer goes through the book of Acts with a fine-toothed comb, pulling out a wealth of historical knowledge, ranging from what would have been common knowledge down to details which only a local person would know.  Again and again Luke’s accuracy is demonstrated: from the sailings of the Alexandrian corn fleet to the coastal terrain of the Mediterranean islands to the peculiar titles of local officials, Luke gets it right.  According to Professor Sherwin-White, “For Acts the confirmation of historicity is overwhelming. Any attempt to reject its basic historicity even in matters of detail must now appear absurd.”  The judgement of Sir William Ramsay, the world-famous archaeologist, still stands: “Luke is a historian of the first rank. . . .   This author should be placed along with the very greatest of historians.”  Given Luke’s care and demonstrated reliability as well as his contact with eyewitnesses within the first generation after the events, this author is trustworthy.

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The Existence of God

(Previously published in serial form.)   Click here.

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