Introduction
Plantinga: How
can there be concord between science and religion?
à
“One way would be as follows: scientific discoveries provide premises for good
arguments for the existence of God.”[1]
Two examples:
(1) Fine
tuning arguments, i.e., scientific discoveries in physics and astronomy about
the structure of the universe (Ch. 7)
(2) Arguments
from biology, i.e., arguments involving the nature and character of the living
beings our world displays[2]
(Ch. 8)
I. Fine-tuning
Fine-Tuning Argument –
[S]everal
of the basic physical constants – the velocity of light, the strength of the
gravitational force, and of the strong and weak nuclear forces – must fall
within very narrow limits if intelligent life of our kind is to develop.[3]
Flatness problem – life is possible only because the
universe is expanding at just the rate required to avoid recollapse.[4]
One
reaction to these apparently enormous coincidences is to claim that none of
this ought to be seen as requiring explanation: after all, no matter how things
had been, it would have been exceedingly improbable that they be that
particular way.[5]
Plantinga: How is
this relevant?...Would this explanation pay in Dodge City?[6]
Assuming
the values of these [six] parameters are independent of each other, the
fine-tuning is of course multiplicative: the probability (on chance) that all
six of the dials will be tuned to life-permitting widths is less than 10-100.[7]
Reply 1: It isn’t
known that these variables are independent.[8]
Q1: What do think
about reply 1 and Plantinga’s response?
Plantinga: How do
we turn fine-tuning into an argument for theism?
à The basic idea is that
such fine-tuning is not at all surprising or improbable on theism God
presumably would want there to be life, and indeed intelligent life with which
(whom) to communicate and share love. Of course this life could take many
different forms (indeed, perhaps it has taken many forms)…[If God] wanted to
create human life in a universe like ours, he would have been obliged to
fine-tune the constants. On the other hand, on the atheistic hypothesis
according to which these constants have their values by chance (that is, those
values are not the result of anyone’s choice or intention) it is exceedingly
improbable that they would be fine-tuned for life. This seems to offer support
for theism: given theism, fine-tuning is not at all improbable; given atheism,
it is; therefore, theism is to be preferred to atheism.[9]
Q2: What do you
think about Plantinga’s argument above?
Reply 2: It isn’t
known that these variables could have been “tuned” otherwise (mention how these
constants came to be, i.e., by the cooling of the universe)
Q3: What do you
think about reply 2 and Plantinga’s response?
II. Objections
A. The Anthropic Objection
The Anthropic Principle –
A
necessary condition of anyone observing these values of the constants is that
those constants have very nearly the values they do have. We are here to
observe these constants only because they have the values they do have; if the
universe were not fine-tuned, we wouldn’t be here to note that fact.[10]
Plantinga: This
seems right, but how is it an objection to the FTA?
à The problem is
supposed to be that with respect to our evidence here (that the universe is fine-tuned)
there is an “observational selection effect” (OSE): we are arguing that the
universe is fine-tuned, but it isn’t possible that we should observe that it is
not fine-tuned. We could not have
failed to have the evidence we do in fact have; we could not instead have
observed that the universe is not
fine-tuned; and this fact is supposed to invalidate the argument.[11]
My
sample class is such that it couldn’t have contained a counter-example to my
conclusion even if there were one; there is excellent reason, therefore, to
doubt that the sample class is representative; and this ruins the argument.[12]
Plantinga: FTA
isn’t of the same form….Arguments involving OSEs aren’t always bad arguments;
why think the FTA is?[13]
Plantinga: I say
it’s much more like the firing squad argument…The problem with the fishing
argument is that I am arguing for a particular proportion of ten-inch fish by
examining my sample, which, given my means of choosing it, is bound to contain
only members that support the hypothesis in question. But in the fine-tuning
case, I am certainly not trying to arrive at an estimate of the proportion of
fine-tuned universes among universes generally. If I were, my procedure would
certainly be fallacious; but that’s not at all what I’m doing. Instead, I am
getting some information about alpha (nevermind that I couldn’t have got
information about any other universe, if there are other universes); and then I
reason about alpha, concluding that [design] is to be preferred to [chance].[15]
à
Eddington’s revised fish netting argument
Q4: Does a
multiverse theory change the situation for Plantinga’s argument; specifically,
does it make FTA more like Eddington’s (original) fish netting experiment?
B. Is the Relevant Probability Space Normalizable?
Formal Objection to
FTA (McGrew, McGrew, and Vestrup) – There is no coherent way to state the
argument.[16]
The
point is we can’t have each of non-discrimination, countable additivity, and
normalizability when assigning probabilities to these propositions…A genuine
probability measure, however, must be additive and normalizable. Hence no FTA
involves a genuine probability measure; therefore FTAs are incoherent.[17]
à Plantinga: [T]heir
objection is clearly defective: it proves too much…Their objection is too
strong in that it eliminates arguments that are clearly successful.[18]
The
history of measure theory is the history of attempts to come to an account of
measure that deals properly with sets of infinite magnitude and is also
intuitively satisfactory. As it turns out, no wholly satisfactory account is
possible. Thus H.L. Royden:
Ideally,
we should like m (the measure) to have the following properties: that m is
defined for every set of real numbers, that the measure of an interval is its
length, that the measure is countably additive, and that it is translation
invariant. Unfortunately, as we shall see…it is impossible to construct a set
function having all of these properties.[19]
Leopold Kronecker
– there aren’t any actual infinities. There may be quantities that approach
infinity as a limit, but there aren’t and couldn’t be any actual infinite
quantities.[20]
Q5: Any thoughts
on the argument above? Do you think FTA is a coherent argument?
C. Many Universes?
[P]erhaps
there are very many, even infinitely many different universes or worlds; the
cosmological constants and other parameters take on different values in each
world, so that very many (perhaps all possible) different sets of such values
gets exemplified in one world or another. If so, however, it’s likely or
inevitable that in some worlds these parameters take on values permitting life,
and of course we would find ourselves in such a world.[22]
à Plantinga: True,
given many universes displaying different sets of parameters, the probability
that one or another of them will be
fine-tined, display a life-permitting set of parameters, is high…But how does
that affect the probability that our
universe, this particular universe is
fine-tuned?...The multi-game hypothesis, even if true, is irrelevant. No doubt
someone in one of those enormously many poker games deals himself all the aces
and a wild card without cheating; but the probability that I (as opposed to someone or another) am honestly dealing in that magnificently
self-serving way is very low.[23]
Neil Manson:
[T]he “This Universe” objection helps itself to some non-obvious metaphysical
assumptions the most important of which is that the Universe could have taken
different values for its free parameters…whether the values of its free
parameters are among the essential properties of a universe will depends, we
think, on what a given multiverse theory says a universe is.[24]
Plantinga: Is it
plausible or reasonable to claim that the universe [or the elementary particles
that are spatiotemporally relate to those that are pars of the universe] has
these properties essentially?[25]
à
[I]t certainly seems that these things could exist even if the parameters in
question had slightly different values.[26]
Q6: Do you think
how things seem to Plantinga, or to anyone else for that matter, provides any
sort of defense against objections like Manson’s?
Plantinga: The FTA is far from conclusive; it is epistemically
probable, though by no means epistemically certain, that our universe could
have failed to be fine-tuned; therefore, the probability that it is fine-tuned, given the atheistic
many-universe hypothesis, is low, much lower than on the hypothesis of theism.[27]
Q7: What does it
mean for something to be epistemically probable? Given how far outside our
intuitions the present topics lie, do you think the concept of epistemic
probability is a helpful one?
Spinoza offers an alternative analysis of modal terms that might
be relevant here:
[T]here
is nothing to justify us in calling things contingent, I wish to explain
briefly what meaning we shall attach to the word contingent; but I will first
explain the words necessary and impossible…A thing is called necessary either
in respect to its essence or in respect to its cause; for the existence of a
thing necessarily follows, either from its essence and definition, or from a
given efficient cause. For similar reasons a thing is said to be impossible;
namely, inasmuch as its essence or definition involves a contradiction, or
because no external cause is granted, which is conditioned to produce such an
effect; but a thing can in no respect be called contingent, save in relation to
the imperfection of our knowledge…A thing of which we do not know whether the
essence does or does not involve a contradiction, or of which, knowing that it
does not involve a contradiction, we are still in doubt concerning the
existence, because the order of causes escapes us,—such a thing, I say, cannot
appear to us either necessary or impossible. Wherefore we call it contingent or
possible.[28]
D. Can We Come Up with the Relevant Probabilities?
3 ways to interpret FTA[29]
(1) In
terms of Bayes’ theorem
Elliot Sober: Antecedent
probabilities are too hard to discover – or perhaps to subjective, in that
different people will make very different estimates of them.
(2) Likelihood
version – If fine-tuning is more to be expected given theism than given
atheism, then the existence of fine-tuning confirms theism over atheism.[30]
On this interpretation of FTA, P(F/T) is greater than P(F/T), and therefore
theism is to be preferred to atheism, at least with respect to the evidence of
fine-tuning.
Elliott Sober –
We can’t make a sensible estimate of P(F/T).[31]
The
problem is to say how probable it is, for example, that the vertebrate eye
would have feature F1,…Fn if the eye were produced by an intelligent
designer…The problem is that the design hypothesis confers a probability on the
observation only when it is supplemented with further assumption about what the
Designer’s goals and abilities would be if He existed.[32]
Q8: What exactly would we expect to
discover about the engineering, so to speak, of organisms or the universe if
they were indeed designed? Even if evolutionary theory weren’t on the table as
an alternative explanation for how organisms are engineered, wouldn’t it still
put a significant strain on the design hypothesis to propose it as the
explanation for the structure of organisms and the universe, i.e., in light of
its apparent design flaws?
Plantinga: But why can’t we just add to
theism those further assumptions Sober speaks of? Why not revise theistic FTA
by adding some further proposition to the hypothesis?[33]
à “But two can play at
that game.” Atheism can build further assumptions into their hypothesis as
well…”What we get here is a sort of arms race in which each side can produce a
series of hypotheses on which F is ever more probable; indeed, each can finally
produce a hypothesis on which the probability of F is 1.”[34]
Plantinga: [H]ow can we determine which
hypotheses are to be compared, i.e., how can we determine which are the right
ones with respect to which to estimate the probability of fine-tuning? On the
Bayes theoretic version of the FTA, it is the prior probabilities that perform
that function; but on the likelihoods version we have to ignore them.[35]
Plantinga: Sadly enough, something
similar holds for the Bayes theoretic version. Here, of course, we do take the
antecedent probabilities into account. But how do we figure out the antecedent
probability of theism? What is the prior probability, prior to consideration of
the evidence, if any, afforded by fine-tuning?[36]
à Epistemic probability
– either high (for a theist) or low (for an atheist); for others, no probability
at all will be able to be assigned[38]
(3) Inference
to the best explanation
Plantinga: Even if [some unlikely]
explanation is the best one, you will quite properly refuse to accept it as the
truth of the matter. And this points to a problem with the FTA construed as
something like an inference to the best explanation; substantially the same
problem that afflicts it construed Bayesianly. Part of what makes an
explanation good or bad is its probability.[39]
Plantinga: It is fairly clear…that FTA,
taken this way – that is, taken as involving antecedent probabilities – offers
at best modest support for theism.[40]
Q9: Do you agree with Plantinga that FTA
lends mild support for theism over atheism? Do you think we have the means
necessary to make reasonable estimates of the relevant probabilities so as to
even justify the attempt at an argument for theism from alleged fine-tuning?
Why or why not?
[1] P. 197.
[2] P. 198.
[3] p. 198.
[4] P. 199.
[5] P. 200-201.
[6] P. 200-201.
[7] P. 203.
[8] P. 203.
[9] P. 203.
[10] P. 204.
[11] P. 205.
[12] P. 205.
[13] P. 206.
[14] P. 207.
[15] P. 208-209.
[16] P. 209.
[17] P. 212.
[18] P. 213.
[19] P. 215.
[20] P. 216.
[21] P. 216.
[22] P. 218.
[23] P. 220.
[24] P. 221.
[25] P. 222-223.
[26] P. 223.
[27] P. 225.
[28] Ethics,
Proposition 33, note 1. url: http://www.gutenberg.org/files/3800/3800-h/3800-h.htm
[29] p. 226.
[30] P. 227.
[31] P. 227.
[32] P. 227.
[33] P. 228.
[34] P. 228-229.
[35] P. 229.
[36] P. 229.
[37] P. 229.
[38] P. 229-230.
[39] P. 230-231.
[40] P. 230.
