William Lane Craig - christelijke apologeet en debater

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Question:

Dear Dr Craig,

In the last talk of the conference Formal Methods in the Epistemology of Religion (June 2009, Belgium), the famous European atheist Herman Philipse raised (in the introduction) a minor worry which I've shared with him for a long time: your Kalam arguments have problematic premise that beginningless causal chain would be (or form) an actually infinite set.

Indeed, if you are a presentist, why should you say that if the past was actually infinite, then the past intervals would form an actually infinite set (as is assumed in Kalam cosmological arguments)?

If only the present temporal realm is real (as the presentist claims), then there are no past intervals to form a set.

If you adopted degree presentism -- saying that the present is more real than the past and the future which are nevertheless also real, but to a lesser degree -- then you could assume multiple past intervals. Yet, then you should assume multiple future intervals, too -- and so you could run some Kalam argument against the infinity of the future. But it seems you want to avoid the conclusion that the future is finite. At least, such a conclusion would generate a problem for eternal heaven and hell: time is essential for humans, and it also does not make sense to say, "after this temporal life, there will be a timeless existence."

Any thoughts on the way out?

Thank you.

Vlastimil


Dr. Craig responds:

Good to hear from you, Vlastimil! Say “Hi” to Paula! It’s gratifying, isn’t it, to see that these issues are finally appearing on the European horizon? I’ve just been invited to contribute essays on the kalam cosmological argument to two German books of essays on the arguments of natural theology. To have such issues even discussed, even if critically, as in the conference you recount, is progress.

Strictly speaking, I wouldn’t say, as you put it, that a “beginningless causal chain would be (or form) an actually infinite set.” Sets, if they exist, are abstract objects and so should not be identified with the series of events in time. Using what I would regard as the useful fiction of a set, I suppose we could say that the set of past events is an infinite set if the series of past events is beginningless. But I prefer simply to say that if the temporal series of events is beginningless, then the number of past events is infinite or that there has occurred an infinite number of past events.

So saying seems to me unproblematic. The problems that arise in this connection are, I think, due to the difficulty of capturing various intuitive notions linguistically because of the presence of tense. For example, there seems to be an intuitive difference between the presentist, who thinks that only the present moment of time exists, and so-called eternalists, who think that all moments of time exist. But many philosophers have noted how difficult it is to express this difference linguistically. For if “exists” is present-tensed, than eternalists agree that the only moment of time that exists is the present! For that is just to say that only the present moment presently exists. On the other hand, if “exists” is tenseless, then the presentist agrees that all moments of time exist! For that just is to say that every moment of time exists at some time or other. Philosophers have resorted to linguistic contortionism in order to express the difference between presentism and eternalism. I think that it’s obvious that these are two different ontologies, even if our linguistic resources fail us in our attempts to express the difference in sentences.

On an eternalist ontology, since all events are equally real, there can be no question that a beginningless temporal regress of events is composed of an actually infinite number of events. Since all events are equally real, the fact that they exist (tenselessly) at different times loses any significance. The question, then, is whether events’ temporal distribution over the past on a presentist ontology precludes our saying that the number of events in a beginningless series of events is actually infinite.

Now we may take it as a datum that the presentist can accurately count things that have existed but no longer exist. He knows, for example, how many U.S. presidents there have been up through the present incumbent, what day of the month it is, how many weeks it has been since his last haircut, and so forth. He knows how old his children are and can reckon how many billion years have elapsed since the Big Bang. The non-existence of such things or events is no hindrance to their being enumerated. Indeed, any obstacle here is merely epistemic, for aside from considerations of vagueness there must be a certain number of such things. So in a beginningless series of past events of equal duration, the number of past events must be infinite, for it is larger than any natural number. But then the number of past events must be ℵ0 (the first transfinite cardinal number), for ∞ (signifying a potential infinite) is not a number but an ideal limit.

The question then arises whether on presentism the series of future events, if time is endless, is not also actually infinite. Intuitively, it seems clear that the situation is not symmetrical, but this is notoriously difficult to express linguistically. It might rightly be pointed out that on presentism there are no future events and so no series of future events. Therefore, the number of future events is simply zero, not ℵ0. (By this statement one means, not that there are future events, and their number is 0, but that there just are no future events.) But on presentism, the past is as unreal as the future and therefore the number of past events could with equal justification be said to be zero.

It might be said that at least there have been past events, and so they can be numbered. But by the same token there will be future events, so why can they not be numbered? Accordingly, one might be tempted to say that in an endless future there will be an actually infinite number of events, just as in a beginningless past there have been an actually infinite number of events. But in a sense that assertion is false; for there never will be an actually infinite number of events, since it is impossible to count to infinity. The only sense in which there will be an infinite number of events is that the series of events will go toward infinity as a limit.

But that is the concept of a potential infinite, not an actual infinite. Here the objectivity of temporal becoming makes itself felt. For as a result of the arrow of time, the series of events later than any arbitrarily selected past event is properly to be regarded as potentially infinite, that is to say, finite but indefinitely increasing toward infinity as a limit. The situation, significantly, is not symmetrical: as we have seen, the series of events earlier than any arbitrarily selected future event cannot properly be regarded as potentially infinite. So when we say that the number of past events is infinite, we mean that prior to today ℵ0 events have elapsed. But when we say that the number of future events is infinite, we do not mean that ℵ0 events will elapse, for that is false.

Ironically, then, it turns out that the series of future events cannot be actually infinite regardless of the infinity of the past or the possibility of an actual infinite, for it is the objectivity of temporal becoming that makes the future potentially infinite only.

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Op woensdag 23 september 2009 01:27 schreef DJ_Ryow het volgende:

The Atheist Experience #622 Don and Matt Rip William Lane Craig a New One!

Matt weer zo duidelijk en juist als het maar kan ook de YouTube comments van Qaatar en deze link zijn het lezen waard.

William Lane Craig = overrated

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Op donderdag 24 september 2009 23:24 schreef ikhouvannoodles het volgende:
Ik heb alvast één video van hem gezien.

Dr. William Lane Craig Responds to Dawkins Book

en dit was mijn comment erop
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Ik weet trouwens niet in welk context Dawkins zijn uitspraak gezegd heeft en ik hoef hem ook niet te verdedigen, maar wat ik wat ik jammer vind is dat Craig het publiek misleid door te zeggen alsof het argument 'waar komt god dan vandaan' direct word gebruikt om de god hypothese te weerleggen.

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Op zaterdag 26 september 2009 01:05 schreef ikhouvannoodles het volgende:
En trouwens kan jij die bewijzen van Craig aan mij laten zien, door middel van een artikel of filmpje? En betreft die ooggetuigen van jezus, kan jij mij een paar bronnen geven waar dat allemaal staat en wie die mensen allemaal zijn?

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Op zaterdag 26 september 2009 08:51 schreef SpecialK het volgende:

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Niet echt aangezien dat argument nooit wordt aangedragen als het logische bewijs dat god niet kan bestaan.

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Op zaterdag 26 september 2009 09:02 schreef Papierversnipperaar het volgende:

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Het is geen argument voor een stelling. Het is om de hypocrisie aan te tonen van de gelovige die roept dat "het heelal toch niet vanzelf uit niets kan ontstaan" om vervolgens met een God aan te komen die zo maar vanzelf uit niets is ontstaan.

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Op zaterdag 26 september 2009 03:00 schreef Prometheus4096 het volgende:
Als zo een figuur over filosofie of wetenschap praat komt er alleen maar onzin uit.

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Op zaterdag 26 september 2009 10:27 schreef Papierversnipperaar het volgende:

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Een belangrijk argument voor een God is dat er een oorzaak voor het universum zou moeten zijn.

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Op zaterdag 26 september 2009 11:01 schreef Papierversnipperaar het volgende:

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Als je voor (de oorsprong van) God andere standaards gebruikt ben je hypocriet.

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Op zaterdag 26 september 2009 11:08 schreef Haushofer het volgende:

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Nee, dan is het hek van de dam.

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Op zaterdag 26 september 2009 11:22 schreef Haushofer het volgende:

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Maar dat probeert iemand als Craig toch juist te doen? De opstanding van Jezus probeert hij krampachtig "historisch aannemelijk te maken" door te beargumenteren dat alle alternatieven onwaarschijnlijk zijn, er moet een schepper achter dit universum zitten door een causaliteitsargumentatie die voor mijn gevoel al decennialang geen hout meer snijdt etc.

Het is in mijn ogen het typische "ik wil graag geloven, en ik zal het intellectueel aannemelijk maken ook!". Als mensen niet zo verdraaid bijgelovig en irrationeel waren geweest had ik geloofd dat dit soort standpunten een tussenfase zijn waarbij het eindstation er een is van erkenning dat dit soort rare vermenging van ratio en religieus denken geen hout snijdt.

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Op zaterdag 26 september 2009 11:32 schreef Haushofer het volgende:
Misschien denk ik te fysisch. Laat ik het es anders formuleren:

Kan iemand een formulering geven van het begrip "causaliteit" wat op de een of andere manier fundamenteler is dan de natuurkundige definitie? Als causaliteit echt een eigenschap is van het universum wat de fysische wereld en de ruimtetijd overstijgt, dan kun je Craig's redenatie al een stuk serieuzer nemen.

Heeft causaliteit een betekenis als je de natuurkundige definitie loslaat?

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Op zaterdag 26 september 2009 12:11 schreef Haushofer het volgende:

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Nee. Causaliteit is gebaseerd in termen van eigenschappen van ruimtetijd, en heeft betrekking op datgene wat zich in die ruimtetijd bevindt. Ruimtetijd is niet gelijk aan datgene wat er in zit. Hetzelfde zie je bijvoorbeeld bij het volgende voorbeeld: informatie (of simpeler: objecten) kunnen niet sneller dan het licht, maar ruimtetijd kan zich prima zo snel uitzetten dat objecten een onderlinge snelheid verkrijgen groter dan de lichtsnelheid! Waarom? Omdat ruimtetijd volgens de ART niet hetzelfde is als datgene wat zich er in bevindt.

Hoe ruimtetijd ontstaat? Dat weten we niet, want de ART is niet meer geldig zodra het om singulariteiten gaat. Ik heb al verscheidene Christenen meegemaakt die dit als ontkenning van het probleem zien, maar het cruciale punt hier is (en daarom gebruik ik dikgedrukte letters): Zonder theorie van quantumgravitatie kunnen we werkelijk niks zinnigs zeggen over wat de oorsprong is van ruimtetijd. Craig gaat, zover ik kan zien, volledig voorbij aan dit cruciale punt (of ik lees er over heen; als je een link hebt, graag).

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The standard model does not - indeed, cannot - explain why the Big Bang occurred, but it can predict that it occured. So the question reduces to whether we have good evidence for this prediction of the standard model. The Hawking-Penrose singularity theormes governing objects in gravitational self-collapse render such an initial cosmological singularity inevitable so long as the equations of classical Geneeral Relativity apply. Some theorists have hoped to avert the initial singularity by the introduction of a quantum theory of gravitation. But even on quantum gravitational cosmological models, such as the Hartle-Hawking model, while the singular beginnning point is smoothed away, the prediction of a finite past and an absolute beginning of the universe remains unaltered, so that, in Hawking's words, the universe 'would quite litterally be created out of nothing'. Thus, Barrow comments, 'This type of quantum universe has not always existed; it comes into being, just as the classical cosmologies could, but it does not start at a Big Bang where physical quantities are infinite...."

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Now it is certainly true that theorists prefer a theory which involves no singularities, since the laws of physics break down at such a point; but that heuristic does nothing to rule out the fact that the correct theory of the universe may well involve singularities. The Hawking-Penrose singularity theorem proves that so long as the General Theory of Relativity holds, an initial cosmological singularity is inevitable. A singular beginning of the universe is not ipso facto unphysical or unscientific, though it may be discomfiting. A theorist is always at liberty, if he has an aversion to singularities, to "cut out" the initial singular point from the model, treating it, in Fitzgerald's words, "as a kind of mathematical limit lacking physical reality."{31} But the discomfiture of an absolute beginning remains unabated. As cosmologist Andrei Linde candidly confesses, "The most difficult aspect of this problem is not the existence of the singularity itself, but the question of what was before the singularity . . . . This problem lies somewhere at the boundary between physics and metaphysics."{32}

Taylor errs in inferring that the presence of an initial cosmological singularity implies an era about which the standard model's predictions are unreliable. The singular state is a durationless point with respect to time, the analogue to a temporal instant; t=0 does not even lie within the history of the universe, much less constitute an era, but lies on the boundary of space-time. Taylor seems to have confused the singular state with the Planck era prior to 10-43 sec after the Big Bang, whose description requires the marriage of GTR and quantum theory to yield a quantum theory of gravitation.{33} Some theorists hope that such a theory will not involve the singularities inevitable in classical gravitation; but this hope may well prove vain. John Barrow has rightly cautioned that "one should be wary of the fact that many of the studies of quantum cosmology are motivated by the desire to avoid an initial singularity of infinite density, so they tend to focus on quantum cosmologies that avoid a singularity at the expense of those that might contain one."{34} Noting the same tendency, Roger Penrose states, "I have gradually come around to the view that it is actually misguided to ask that the space-time singularities of classical relativity should disappear when standard techniques of quantum (field) theory are applied to them."{35} For if the initial cosmological singularity is removed, then "we should have lost what seems to me to be the best chance we have of explaining the mystery of the second law of thermodynamics."{36} What Penrose has in mind is the remarkable fact that as one goes back in time the entropy of the universe steadily decreases. Just how unusual this is can be demonstrated by means of the Bekenstein-Hawking formula for the entropy of a stationary black hole. The total observed entropy of the universe is 1088. Since there are around 1080 baryons in the universe, the observed entropy per baryon must be regarded as extremely small. By contrast in a collapsing universe the entropy would be 10123 near the end. Comparison of these two numbers reveals how absurdly small 1088 is compared to what it might have been. Thus, the structure of the Big Bang must have been severely constrained in order that thermodynamics as we know it should have arisen. So how is this special initial condition to be explained? According to Penrose, we need the initial cosmological singularity, conjoined with the Weyl Curvature Hypothesis, according to which initial singularities (as opposed to final singularities) must have vanishing Weyl curvature.{37} In standard models, the Big Bang does possess vanishing Weyl curvature. The geometrical constraints on the initial geometry have the effect of producing a state of very low entropy. So the entropy in the gravitational field starts at zero at the Big Bang and gradually increases through gravitational clumping. The Weyl Curvature Hypothesis thus has the time asymmetric character necessary to explain the second law. Without the initial singularity we should have white holes spewing out material, in contradiction to the Weyl Curvature Hypothesis, the Second Law of Thermodynamics, and probably also observation.{38} Penrose supplies the following figure to illustrate the difference:

If we remove the initial cosmological singularity, we render the Weyl Curvature Hypothesis irrelevant and "we should be back where we were in our attempts to understand the origin of the second law."{39} Could the special initial geometry have arisen sheerly by chance in the absence of a cosmic singularity? Penrose's answer is decisive: "Had there not been any constraining principles (such as the Weyl curvature hypothesis) the Bekenstein-Hawking formula would tell as that the probability of such a 'special' geometry arising by chance is at least as small as about one part in 101000B(3/2) where B is the present baryon number of the universe [~1080]."{40} Thus Penrose calculates that, aiming at a manifold whose points represent the various possible initial configurations of the universe, "the accuracy of the Creator's aim" would have to have been one part in 1010(123) in order for our universe to exist.{41} He comments, "I cannot even recall seeing anything else in physics whose accuracy is known to approach, even remotely, a figure like one part in 1010 (123)."{42}

Furthermore, the fact that certain quantum gravity models like the Hartle-Hawking model lack an initial singular point is in any case really quite irrelevant to our concern, since such models still posit the finitude of the past and an origination of the universe ex nihilo. As Barrow explains, "This type of quantum universe has not always existed; it comes into being just as the classical cosmologies could, but it does not start at a Big Bang where physical quantities are infinite . . . ."{43} The Hartle-Hawking universe thus gives "a picture of 'creation out of nothing'," even though "one never runs into an unusual point like the apex of a cone."{44}