There is now a lot of soul-searching about the direction of the Republican Party and much doubting of its future viability if does not adapt itself in some way to an electorate that has (it is said) fundamentally shifted over the last few decades. I am a scientist and not a political expert, but science has something to teach us that may be of relevance here: don’t over-interpret the data.

The tendency of “pundits” to over-interpret shows itself with almost every election. Each time a party is ejected from the White House or isn’t, it is supposedly because some new and enduring coalition has been formed and some old coalition has finally disintegrated, or because the nation has turned against (or toward) social conservatism, or an era of Big Government has ended or just started. All nonsense.

The obvious fact is that the national electorate is an extremely heterogeneous lot and votes on the basis of innumerable disparate considerations. This candidate is “presidential,” or sympathizes with people like me, or is hostile to Israel, or is going to cut taxes, or is pro-life, or is going to create green jobs (whatever the heck those are), or has a mellifluous voice¸ or is charismatic, or is weak on defense, or has an annoying voice, and so on. Most voters do not have fully thought-out or consistent positions on most issues, which is why pollsters get different results depending on how they phrase questions or on the order in which they ask them. They want more spending, lower taxes, and less debt all at the same time. Reading into a 52 percent or even a 60 percent victory some kind of Rousseauean “General Will” is absurd.

Why did President Obama win re-election? There are some very obvious reasons that have nothing to do with ideology and in light of which the outcome is not particularly surprising. First, there is the fact that since the days of Grover Cleveland, about 30 elections ago, there has been only one case where a party held the White House for just four years: Jimmy Carter, and he had the Iran hostage fiasco, high inflation, high interest rates, and high unemployment.  It takes a LOT to make it happen. Now you might say that 8 percent unemployment should have been enough to do it. But this brings us to the second reason. People feel that President Obama was dealt a bad economic hand and so are less inclined to want to punish him for the state of the economy than they were in the case of Carter. Third, people have grown weary of war, and they hear less about war now (partly thanks to the media reporting on it less). And then there is the fact that most people seem to find Obama’s personality appealing.

Is this election somehow a repudiation of conservatism or the ideas of the Republican Party? If so, it is hard to understand why the GOP managed to win a sizable majority of House races.  Moreover, it is generally the case that when a party has held the White House for four years they not only retain it, but get a larger margin of victory than the first time, as in 2004, 1996, 1984, 1972, 1964, 1956, 1936, and 1924. You have to go all the way back to Woodrow Wilson’s re-election to find a counterexample. (And even that is not much of one, because his first victory was in a three-way race in which his opponents, Taft and Teddy Roosevelt, split the Republican vote.) The fact that Pres. Obama’s margin this time is much smaller (almost unprecedented) tells us that he survived, not that he or his ideology has enjoyed some kind of rousing vindication.

This is not to say that conservatives shouldn’t do some hard thinking. But it is to say that we should not read too much into the result.

Stephen Hawking is a remarkable person whom I’ve know for 40 years and for that reason any oracular statement he makes gets exaggerated publicity. I know Stephen Hawking well enough to know that he has read very little philosophy and even less theology, so I don’t think we should attach any weight to his views on this topic.

I will only address the question of whether modern governments (such as our own Federal government and State governments) have the right in some cases to execute criminals. Catholic teaching recognizes four purposes of punishment: deterrence, retributive justice, reform of the criminal, and rendering the criminal harmless.

It can be debated whether and under what circumstances the death penalty deters. It seems to me pretty obvious that there are certain crimes that can only be deterred by the death penalty. What could deter a man already serving a life sentence who has an opportunity to escape prison, but can only do so by killing someone, say a prison guard? Not the prospect of imprisonment, since he is already serving a life sentence. Would torture deter him? Maybe, but that would be much harder to justify than the death penalty. So it would seem that only the death penalty might stop him from killing a prison guard—who might have a spouse, children, parents, and friends.

What could deter someone who has already committed a crime that would draw a life sentence and can only avoid capture by killing the police officer? The threat of the death penalty seems the only way. (There is also the practical use of the threat of the death penalty as leverage to get criminals to provide evidence on confederates who might otherwise escape punishment.)

Then there is retributive justice. I don’t know what Bottum’s “high justice” is. As far as I am aware, it is not a term of either in the law or in moral philosophy. Forget “high justice,” whatever it is, and let’s just talk about plain old justice. The threat of a $5 fine would not deter a murderer, but is that the only reason we would find such a light punishment morally repugnant? Would we not also think it failed to satisfy the minimal requirements of retributive justice?

Retributive justice does not require that the punishment be of exactly the same degree of severity as the crime—which, in any case, isn’t always possible. But it does seem to require that there not be an extreme disproportion between the gravity of the crime and the severity of the punishment.

Just as I would say that a $5 fine for murder is a travesty, so I would say that a prison sentence for what the BTK killer did is a travesty. Call this “risible” if you will, but that is what my moral instincts tell me. Setting aside for the moment whether certain crimes “cry out to heaven” for justice, certain crimes against society cry out for justice from the state.

Romans 13 does not, I agree, legitimize punishing any and every crime by the death penalty. No one ever said it did. The question is whether it legitimizes some applications of the death penalty, and it seems to me pretty obvious that it does.

Does St. Paul calling the magistrate “God’s minister” mean that his justification of punishment applies only to explicitly religious states? Clearly not. What St. Paul says in Romans 13 about the authority of magistrates is in line with what the New Testament says in many places about legitimate authority of every type, whether it be of parents over children, masters over servants, or temporal rulers over their subjects. Such authority comes from God—even if wielded by people who do not acknowledge God.

It comes from God both in the sense that it is sanctioned by God and in the sense that obedience to it is obedience to God. A child who obeys his parents in what they legitimately command is by so doing also obeying God, even if the child is Christian and the parents are atheists or Buddhists or polytheists or Scientologists. Ephesians 3:15 tells us that “all fatherhood takes its name” from the Father who is in heaven, even for fathers who do not believe in a father in heaven.

Even a secular state has legitimate authority whose purpose is to maintain a just order in the temporal sphere. Whatever legitimate authority the state has it receives from God—even if it does not acknowledge God explicitly. The punishing of criminals is part of that authority. Even the government of a state based on some pagan religion that has no god or many gods has the right—indeed the obligation—to protect society and do justice by punishing criminals. And from the Christian point of view both that right and obligation come from God.

Nor does the fact that a government fails to uphold its obligations in some respects necessarily nullify its authority in other areas. (The fact that the U.S. government fails to protect life in the womb, for example, does not mean that it no longer has the authority to punish other crimes.) That would be an absurd proposition that would lead to perpetual chaos and make all government impossible.

Some of the arguments that would deny modern states any right to use the death penalty would also deny them the right to use any grave punishment, including life in prison. After all, we can also ask by what right a government takes away the last fifty years of a man’s life. Why isn’t that also “high justice”? It is a damn high price for anyone to pay, as an old friend of mine who is paying that price can attest.

The Catholic Church has taught quite explicitly at least since the time of St. Augustine, and continues to teach, that the state does have the right in some circumstances to use the death penalty. There may be all sorts of reasons why it would be a bad idea to exercise that right in modern times. It may do more harm than good.

I am not here pushing for the death penalty to be used more widely, or at all. But I do think a respectable (as opposed to risible) case can be made for its continued use in some cases. And I do think that we must be careful that the force of our moral passion not bend out of shape or even break the framework of moral analysis so carefully constructed over two millennia of theological reflection.

What are neutrinos and why does anyone care about their mass? Three kinds of particles have been observed so far and are the building blocks of the Standard Model of particle physics:

(1) There are particles called “gauge bosons” associated with the basic forces. Two particles exert a force on each other by exchanging one of these gauge boson particles (i.e. by one particle emitting a gauge boson and the other particle absorbing it). The exchange of gauge bosons is said to “mediate” the force. (Perhaps theologians will find that interesting.) Indeed, for all the forces except electromagnetism, two gauge bosons can interact with each other by exchanging a third gauge boson. In that case, gauge bosons are both the things interacting and the thing by which they interact—the things related and the thing relating them. Indeed, in the basic interation, whereby one gauge boson emits another (in which there are three particles involved: one in the initial state and two in the final state) there is a basic symmetry among the three particles involved, so that it is a matter of point of view which is being emitted and which is emitting. (Which may also interest theologians who look for analogies in nature of supernatural realities: ‘subsistent relations’ anyone?) But I digress!

(2) There are particles called “leptons”, which include the familiar electron. There are three “families” of leptons. In the first family there is the electron and the “electron neutrino”. In the second family, there is a particle just like the electron, except about 206 times heavier, called the “muon”, and also the “muon neutrino”. In the third family, there is a particle just like the electron and muon, except about 17 times heavier than the muon, called the “tauon” (aka “tau” or “tau lepton”), and also a “tau neutrino”. I will return to the neutrinos shortly.

(3) There are particles called “quarks”, which also come in three families. In the first family are the u and d quarks; in the second are the much heavier c and s quarks; and in the third are the yet much heavier t and b quarks. The u and d quarks are particularly important, because the protons and neutrons are mostly composed of them.

Why are there three families? No one knows. Ordinary matter needs only the first family particles (electrons and u and d quarks). It would seem that the world would not look much different if there were only one family. (However, the second and third family may play subtle indirect roles that greatly affect how the world looks.) Except for their large masses, the three families are Xerox copies of each other. The first particle discovered that belonged to one of the heavier families was the muon in 1937. The Nobel laureate physicist I.I. Rabi, greeted its discovery with the famous quip, “who ordered that?” a question inspired by dining at Chinese restaurants. To this day, no one knows the answer why there is this seemingly superfluous duplication—or rather triplication—of particles. The numerologically inclined theologian may be tantalized by the fact that the number three crops up repeatedly in fundamental physics: There are three families of quarks and leptons; three non-gravitational forces (strong, weak, and electromagnetic—gravity is very different from the other forces); three gauge bosons of the weak force; three ‘colors’ (analogous to electric charge) for the strong force; the electric charges of quarks are multiples of 1/3 the charges of leptons; there are three dimensions of space (or at least three “large” space dimensions).

Neutrinos are extremely elusive. Because they do not interact via the strong or electromagnetic forces, they ordinarily pass right through matter. This inspired John Updike to write an amusing poem about them many years ago:

Cosmic Gall

Neutrinos, they are very small.
They have no charge and have no mass
And do not interact at all.
The earth is just a silly ball
To them, through which they simply pass,
Like dustmaids through a drafty hall
Or photons through a sheet of glass.
They snub the most exquisite gas,
Ignore the most substantial wall,
Cold-shoulder steel and sounding brass,
Insult the stallion in his stall,
And scorning barriers of class,
Infiltrate you and me! Like tall
And painless guillotines, they fall
Down through our heads into the grass.
At night, they enter at Nepal
And pierce the lover and his lass
From underneath the bed-you call
It wonderful; I call it crass.

The New Yorker Magazine, Inc., 1960

Notice that Updike refers to neutrinos entering the earth at night from Nepal. What he is referring to is the fact that the Sun emits an enormous flux of neutrinos. So, during the day, “solar neutrinos” stream down on us, and at night, they stream up at us, having rained down on the other side of the earth and passed entirely through it. There are two other kinds of neutrinos hitting us all the time. The universe is filled with neutrinos—roughly the same number as there are particles of light. These come at us equally from every direction. There are also lots of neutrinos produced in the atmosphere when highly energetic particles (e.g. protons) from outer space (“cosmic rays”) impinge upon the earth, as they do in copious quantities. These are the so-called “atmospheric” neutrinos”.

If neutrinos pass right through matter, how does one ever detect them? After all, detectors are made of matter, and the neutrinos should pass right through them too. The answer is that neutrinos interact extremely weakly, but do interact. So the vast majority do pass through matter, but on rare occasions one does interact with ordinary matter. (This is governed by quantum mechanics, so that which one interacts is a matter of chance.) By having a huge amount of ordinary matter in one’s detector, one gives neutrinos more opportunities to interact. That is why neutrino detectors typically contain thousands of tons of water or metal or some other material.

In the so-called Standard Model, which is now about 40 years old, neutrinos are massless particles (as “photons” and “gravitons” are also believed to be). Hence John Updike’s statement that “they have no mass”. For a long time, however, theorists speculated that neutrinos may actually have a tiny mass. If neutrinos have mass, then a very curious phenomenon becomes possible: one type of neutrino (say, a “tau neutrino”) can slowly morph into another type (say, a “muon neutrino”). In fact, neutrinos should morph into each other and back again in a periodic way—hence these are called “neutrino oscillations”

Since the 1960s there have been hints in the data that this effect was happening in “solar neutrinos”. Since people understood fairly well how the Sun burns, i.e. the nuclear reactions that power the Sun, they could calculate the rate at which neutrinos are streaming out of the Sun. (This is closely related to how much light is coming out of the Sun.) They started measuring the “flux” of solar neutrinos in the 1960s using the large detectors I was talking about. They saw only about half as many neutrinos as should have been there. An explanation suggested by theorists at the time was that en route from the center of the Sun to the earth about half the solar neutrinos (which start off as electron neutrinos) “oscillated” into muon neutrinos, which the detectors of that time could not see. This turns out to be correct, but because of uncertainties in the precise details of how the Sun burns, this remained unconfirmed until the late 1990s. Meanwhile in 1998 another big discovery was made: In the so-called “atmospheric neutrinos” I mentioned earlier, many muon neutrinos were oscillating into tau neutrinos. These two results showed that neutrinos have non-zero (but tiny) masses. The mass of the heaviest neutrino is roughly 10 million times lighter than an electron.

This fact tells us that there is something going on that lies beyond the original Standard Model. The most likely possibility is that these neutrino masses come from processes that are predicted to exist in so-called “grand unified theories”—theories that unify the three non-gravitational forces. They are therefore windows onto a realm of phenomena that are very hard to get any direct information about. That is one reason why theorists are very interested in them.

What have the experiments the LA Times is talking about now seen? The oscillations of muon and tau neutrinos have (it is reported) now been seen directly in the laboratory. They produced a beam of muon neutrinos (which came from the decay of “muons”) at an accelerator (at CERN) and allowed that beam to propagate for many miles until they were largely morphed into tau neutrinos. Some of those tau neutrinos then interacted and produced “tau leptons” (remember: a heavier version of the electron). These tau leptons were then observed. This was a very direct confirmation of what was shown by more indirect means in 1998.

Here is what CWN reports:

Stating that “Catholics can become fanatical about one form of the Body of Christ in the bread of the Eucharist as the REAL presence of Christ,” Father Michael Kelly, the Jesuit CEO of the Asian Catholic news agency UCA News, criticized the doctrine of transubstantiation in a May 24 column.

In his column– a critique of the new, more accurate liturgical translations that reflect the content and dignity of the original Latin– Father Kelly writes:

“Regrettably, all too frequently, the only Presence focused on is Christ’s presence in the elements of bread and wine. Inadequately described as the change of the ‘substance’ (not the ‘accidents’) of bread and wine into the body and blood of Christ, the mystery of the real presence of Christ in the Eucharist carries the intellectual baggage of a physics no one accepts. Aristotelian physics makes such nice, however implausible and now unintelligible, distinctions. They are meaningless in the post-Newtonian world of quantum physics, which is the scientific context we live in today.”

It was a standard maneuver of dissident theologians in the 1960s to affect incomprehension of binding doctrine rather than honestly and forthrightly saying that they rejected it. No one is fooled by that transparent ploy anymore, and one assumes that Fr. Kelly realizes that. It must be, therefore, that he is genuinely confused. I will try to unconfuse him.
The Church has made it clear that one does not have to accept all of Aristotelian philosophy to accept the doctrine of transubstantiation. The substance of the doctrine (so to speak) is easily explained without the Aristotelian terminology. To say that ‘the accidents of bread and wine’ remain after consecration means that empirically the consecrated elements are completely indistinguishable from bread and wine. They taste like bread and wine; they look like bread and wine; they would, if made to react chemically or placed in a mass spectrograph, behave in every way just as bread and wine do. To say that ‘the substance’ of the consecrated elements is the Body and Blood of Christ, means that in reality the elements are no longer bread and wine but are the Body and Blood of Christ.

If one looks at the consecrated elements and asks ‘What are these?”, the correct answer (according to the doctrine of transubstantiation) is “These are the Body and Blood of Christ.” If one asks, “What do these appear to be under any empirical test?”, the answer is “bread and wine.” Basically, that is all there is to it. The dogmatic definition used Aristotelian terminology to express this, but it can be expressed without that terminology.

Some alternative beliefs to transubstantiation are the following:

(a) The consecrated elements not only appear to be but are bread and wine, and only symbolize the Body and Blood of Christ.

(b) The consecrated elements are not in themselves the Body and Blood of Christ, but spiritually and in effect are for the believer who consumes them, in the sense that when the believer consumes them he is united in a spiritual manner with the Body of Christ. (The corollary being that if the elements are not consumed or are consumed by a non-believer, they are not the Body and Blood of Christ. Thus the “presence” of Christ depends on both what is done with the consecrated elements and on the internal disposition of the recipient.)

(c) The consecrated elements are still bread and wine, but in some way the Body and Blood of Christ is also present with them or in them in a manner that is objective in that it does not depend on the disposition of the recipient (“consubstantiation”).

In short, one can explain the doctrine of transubstantiation and distinguish it from other beliefs about the Eucharist without any use of the Aristotelian apparatus. I don’t know what quantum mechanics has to do with any of this. If anything, quantum mechanics makes a straightforward connection between what appears empirically and what is “really there” more obscure than it was in Newtonian physics, and to that extent would make it easier rather than harder to affirm the doctrine.

I am going to explain in non-technical language what this is all about, and why it is interesting to physicists. Before I do so, however, I should note that the result is not yet a discovery. Some of the results announced are still only at the “2 sigma” or “3 sigma” level, which means that they could be statistical aberrations. It will take further experiments to nail down what is going on.

The almost-discovery at FNAL has to do with whether the laws of nature treat matter and antimatter in a perfectly symmetric way. For every kind of fundamental particle there is a corresponding kind of antiparticle. The antiparticle of a proton is an antiproton, for example. (The antiparticle of an electron would be called an antielectron if nomenclature were consistent, but it is almost always called a “positron”, because that is what it was called a long time ago, and the name stuck.) A particle and its antiparticle are in some ways exactly the same (e.g. they are believed to have exactly the same mass). In some ways they are opposite (e.g. they have opposite electrical charge). In the terminology of physics, a particle and antiparticle can “annihilate” each other. That is really an abuse of language, however. “Annihilate” literally means to reduce to “nothing”. Actually, when a particle and antiparticle meet, they disappear, but something of equal energy is produced—often another kind of particle-antiparticle pair. For example, a proton and antiproton could annihilate into an electron and positron. Some particles are their own antiparticle: for example the antiparticle of a photon (particle of light) is a photon.

There is strong reason to believe that soon after the Big Bang explosion the universe had exactly, or almost exactly, the same amount of matter and antimatter. If that had remained the case, it would been terrible for us, because eventually the protons and antiprotons would have (almost) all annihilated, as would the electrons and positrons, and so forth, leaving things like photons out of which it is impossible to make interesting structures, like you and me.

So, it must have been the case that some processes happened very early in the history of the universe to generate an excess of particles over antiparticles. Then, when the antiparticles eventually annihilated with particles, the excess particles would have remained—and that is what stars, planets, and living things are made of. The process by which an excess of matter over antimatter was produced early in the history of the universe is called “baryogenesis”. (“baryo-“ here refers to a kind of particle called baryons, of which protons and neutrons are examples.)

In order for processes to create an excess of matter (also called a “matter-antimatter asymmetry” or “baryon asymmetry”) the laws of physics must not treat matter and antimatter in a perfectly symmetric or even-handed way. That is, a certain putative symmetry of the laws of physics called “C” must be “violated.” (“C” is a mathematical operation that interchanges—“conjugates”—particles and antiparticles.) More importantly, a putative symmetry called “CP” must be violated by the laws of physics. (CP interchanges particles and antiparticles, and at the same time interchanges “left” and “right”.)

It has been known since 1964 that CP is, in fact, violated by a certain force of nature called the “weak interaction.” For a quarter of a century, however, this effect (“CP violation”) was seen in the laboratory only in processes involving particles called “neutral kaons”, and then it was seen also in similar processes involving neutral “B mesons”. (The processes being studied in this Fermilab experiment also involve B mesons.) To this day, CP violation has only been observed in process involving these two kinds of particles. The CP violation so far observed is very well accounted for by our current theory of particle physics, called “the Standard Model”. It is all traceable to the fact that a certain quantity appearing in the laws of physics is a “complex number” rather than a “real number”. It has been shown, however, by theoretical calculations, that the CP violation that is built into the Standard Model and the kinds of processes that the Standard Model allows are not adequate to account for the matter-antimatter asymmetry of the universe. By themselves they would have produced such an asymmetry, but one far smaller than actually exists.

How then did the asymmetry between matter and antimatter come about? This is not a mystery in the sense of something very difficult to explain. If anything, it is too easy to explain. There are hundreds of theories of “baryogenesis” on the theoretical-particle-physics market. (I have proposed several of them myself.) All of them postulate “new” particles and forces, i.e. ones not contained in the Standard Model. Which, if any of these theories is correct remains to be seen.

What is exciting about the new results from Fermilab is that (if they pan out) they will be the first time any CP violation that is not accounted for by the Standard Model has ever been seen in the laboratory. That would raise the possibility that these could be the kinds of processes that generated the matter-antimatter asymmetry in the early universe. I stress the word “possibility”, because it is also quite possible that the CP-violating processes that (perhaps) have been seen at Fermilab are not the ones responsible for the matter-antimatter asymmetry.

In any event, these are the kinds of theoretical issues involved in these new results. Are there any philosophical or theological implications in any of this? No, at least none of any great significance.

This isn’t about “explaining existence” as the headlines say. To explain “existence” is to explain why there is anything at all—why there is a universe at all and why there are laws of physics at all. This is merely about stuff turning into other kinds of stuff. More specifically, these experiments are about how certain kinds of particles turn into other kinds of particles—how antiparticles can (in effect) turn into particles. Really, it is about bookkeeping. It is about how a ledger that contained equal numbers in its particle and antiparticle columns turned into one that doesn’t. That is no more metaphysically significant than understanding how the balance in some financial ledger goes from being in the black to being in the red. Except that money, it seems, really can be “annihilated”, as so many have learned recently to their great sorrow.

Hubble Space Telescope

Below, I give links to some of the most fantastic awe-inspiring images taken by Hubble. (These are found at the marvelous site “Astronomy Picture of the Day”). Maybe I am just a simpleton, but I don’t see how anyone can look at pictures like this and not believe in God. Hubble isn’t just about beautiful pictures, though. It has enormously increased our understanding of the universe. This site lists the “top ten” discoveries of HST. The most fundamental, I think most scientists would agree, was the discovery announced in 1998 that the universe’s expansion is accelerating rather than slowing down. This discovery wasn’t made with HST alone, ground based telescopes were also involved. (A nice explanation of how one tells that the universe’s expansion is accelerating is here.) This discovery tells us something about the fate of the universe; it suggests that the universe will not eventually reverse its expansion and end in a Big Crunch, but will expand forever, getting ever colder and emptier in an sempiternal black oblivion. (Suggests, but does not prove—it could be that the expansion will stop Kick Ass (2010) accelerating and start decelerating and even reverse at some point.)

So, all hail the Hubble space telescope! Enjoy the view:

The famous “Pillars of Creation”

Tenth Anniversary: A Planetary Nebula

The Eskimo Nebula

A Supernova Remnant

The Cat’s Eye Nebula

The Deep Field: Universe at age 1 billion yrs

Even Deeper: Universe at age ½ billion yrs

Unusual Spiral Galaxy

Bright Spiral Galaxy M81

An Edge-on Look at a Galaxy

A Galaxy Face-on

The Ring Galaxy

The Carina Nebula

The Omega Nebula

The Trifid Nebula

The Orion Nebula

The Crab Nebula

The Butterfly Nebula

The Spirograph Nebula

A Star Jet: a jet of gas trillions of miles long

Stars Being Born

More Baby Stars

The Dumbbell Nebula

Shock waves from a supernova

The Hubble Double Bubble planetary nebula

Tracking Jupiter’s Great Red Spot

We have learned or will learn far more about the universe from the Hubble Space telescope, from satellites like PLANCK and WMAP, and from many other experiments and observatories than we would learn from landing people Mars.

Yes, astronauts jumping around on Mars would be sensational and excite people’s imaginations. That could stimulate interest in science and support for funding. In other words, its value is almost entirely as a publicity stunt. But it is an incredibly expensive publicity stunt. Most astrophysicists I have talked to think that a manned mission to Mars is a horribly inefficient use of research dollars. It will suck resources out of projects that are scientifically vastly more important.

If you love science, and care anything about the taxpayer, please don’t plan a manned mission to Mars!

I agree with you that there is nothing wrong with making “arguments from personal incredulity.” All of us necessarily make judgments based on what we find reasonable or plausible or antecedently probable. And you are right in observing that both ID and anti-ID people make such judgments. Some ID people think natural explanations of certain complex biological structures are as unlikely as walking to the moon. And some anti-ID people think miraculous explanations of these same structures are as unlikely as walking to the moon.

Still, I think Hart is basically right.

One can interpret “irreducible complexity” arguments in two ways. (a) They could be seen as attempts at rigorous proofs that certain structures, such as the blood clotting system or the bacterial flagellum, could not have arisen by small successive steps. In your words, they could be seen as attempts to “rule out” that possibility. Or (b), they could be regarded merely as statements that it is difficult to see how certain things could have arisen by small steps and that it is therefore, as you put it, “warranted [to search] for an alternate explanation.” As (a), irreducible complexity arguments fail. If one is to take them at all seriously, therefore, one must regard them as (b). But to regard them as (b) is to say, in effect, that they are arguments from personal incredulity. That is not to damn them. (And I don’t think Hart intended to damn them.) It is only to say that they fall very far short of being proofs of anything.

Why do I say they fall far short of being proofs? Consider an example that several people have used: a Roman arch. A Roman arch cannot stand unless all the stones that compose it are in place. And that would suggest that it cannot be built one stone at a time—i.e. it would seem to be “irreducibly complex”. Nevertheless, there is a way it can be built up one step at a time: First build a stone wall one stone at a time and one layer at a time. Then remove stones, one at a time, to leave an arch. This illustrates the difficulty in demonstrating the irreducible complexity of something. And that was Hart’s point: irreducible complexity “can never be logically demonstrated.” Or, at least, it is hard to carry out such a demonstration in practice.

Another point I think worth emphasizing: If an ID-skeptic says that a miraculous explanation of the complexity of certain structures seems to him as unlikely as someone having walked to the moon, it is not necessarily because he is “committed to atheistic materialism.” For example, I believe that miracles, by God’s power, can and occasionally do occur. Therefore, I believe that God could miraculously transport someone to the moon. Nevertheless, I think it improbable in the highest degree that anyone has ever been miraculously transported to the moon or ever shall be. In the same way, and for much the same reasons, a person who is a believer both in God and in the possibility of miracles might judge it highly implausible that complex biological structures such as the blood clotting system or the bacterial flagellum arose by miracles—which, in effect, is what ID claims.

Finally, while it perfectly reasonable to put forward the possibility that certain biological structures arose by miracles, that does not mean that the ID conjecture is a scientific one and should be taught as such in science classes. As I have said elsewhere, Moses parted the Red Sea, but that was not a new effect in hydrodynamics; miraculous cures may occur at Lourdes, but they are not new discoveries in oncology; and Jesus turned water into wine, but he did not thereby teach us anything new about organic chemistry.

When I read Mike Behe’s fascinating book Darwin’s Black Box, I was impressed at the complexity of the biological structures he described. They do indeed give the appearance of irreducible complexity. And this constitutes a great challenge for biological science. (That word “challenge”, by the way, is in the title of his book.) But the challenge does not seem to me to be manifestly impossible, like walking to the moon by natural means. But, then, that is the thing about personal incredulity, isn’t it? What is credible to one person is not credible to everyone.