The argument from miracles
Over the course of the last few weeks, we have discussed versions of most of the central philosophical arguments
for the existence of God.
I think that these arguments are interesting and important. Nevertheless, I think that it is fair to say that most religious
believers throughout history have not come to believe in God on the basis of the arguments we have discussed so
far. The argument we’ll be discussing today has probably been discussed less by philosophers than the ones we have
already covered, but has probably been more influential in actually convincing people that God exists.
This is the argument from miracles. There is a long tradition in Christianity of thinking that various miracles can
provide the basis for belief in the existence of God.
For example, in Chapter 20 of the Gospel of John, after the story of Thomas, John writes:
“Now Jesus did many other signs in the presence of (his) disciples that are
not written in this book. But these are written that you may come to believe
that Jesus is the Messiah, the Son of God, and that through this belief you
may have life in his name.”
The idea seems clearly to be that we can, and should, come to believe on the basis of John’s telling us about the
miracles performed by Christ. This idea has been widely accepted; St. Augustine, for example, is quoted as saying
that he would not be a Christian but for the miracles.
This raises the question: can the sorts of testimony that we get from St. John give us good reason for believing
in God? In our reading for today, Hume argues that this is not possible; Hume’s central claim is that we cannot
be justified in believing in God on the basis of testimony about miracles.
This raises the question: can the sorts of testimony that we get from St. John give us good reason for believing
in God? In our reading for today, Hume argues that this is not possible; Hume’s central claim is that we cannot
be justified in believing in God on the basis of testimony about miracles.
But before evaluating Hume’s argument, we should try to get a handle on why someone might think that miracles do
provide evidence for the existence of God. How might one argue for the existence of God on the basis of miracles?
The following rather straightforward argument suggests itself:
The argument from miracles
1. There have been miracles.
2. If there have been miracles, God exists.
_____________________________________________
C. God exists.
The argument from miracles
1. There have been miracles.
2. If there have been miracles, God exists.
_____________________________________________
C. God exists.
Obviously, the argument is valid, so the only question is whether the premises are true. Hume’s argument focuses
on the question of whether we have any good reason to believe premise (1). But let’s focus first on premise (2).
What, exactly, is a miracle?
According to Hume, a “miracle is a violation of the laws of nature.”
This might seem puzzling. After all, aren’t laws of nature supposed to be universal exceptionless claims? (If we
find an exception to a supposed law of nature, it seems that the right response is to say that what we thought was
a law of nature in fact is not.) And if this is what laws of nature are, isn’t the idea of a miracle just a contradiction?
This seems to be a very quick and easy argument against the possibility of miracles.
But it is not a very impressive argument. Believers in miracles take there to be moments in history at which God
suspends the usual natural order. But because this suspension of the natural order has a supernatural cause, it is
natural to think that it is not simply a counterexample to the relevant laws of nature, but rather an exception which,
because of the kind of exception it is, does not falsify the law in question for cases in which there is no
supernatural intervention.
Aquinas gives a definition of a miracle which is, for our purposes, more useful. According to Aquinas,
“those things are properly called miracles which are done by
divine agency beyond the order commonly observed in nature.”
This is a good a definition of “miracle” as any, and we will take this to define the term for our purposes.
If this is the definition of “miracle”, then premise (2) of our argument is trivially true. The remaining questions are: is
premise (1) true? and Do we have any good reason to believe that it is true?
God on testimony that miracles have occurred. He says:
The argument from miracles
“. . . therefore we may establish it as a maxim, that no human testimony can
1. There
have
been miracles.
have such force as
to prove
a miracle,
and make it a just foundation for any
system of religion.”
2. If(88)
there have been miracles, God exists.
_____________________________________________
C. God exists.
This is Hume’s conclusion. We now need to understand his argument for it, which begins
with some premises about the role of perceptual evidence and testimony in the forming
of beliefs.
Aquinas gives a definition of a miracle which is, for our purposes, more useful. According to Aquinas,
“those things are properly
called miracles
which are done by
2.1 Testimony
and evidence
divine agency beyond the order commonly observed in nature.”
Hume’s first claim is that we should base belief on the available evidence:
This is a good a definition of “miracle” as any, and we will take this to define the term for our purposes.
“A wise man, therefore, proportions his belief to the evidence. . . . He weighs
If this is the definition
of experiments:
“miracle”, then
premise which
(2) of side
our is
argument
trivially
true. The remaining questions are: is
the opposite
He considers
supportedisby
the greater
premise (1) true?
andof Do
we have any
goodside
reason
to believe
it is
true?
number
experiments:
To that
he inclines,
with that
doubt
and
hesitation;
and when at last he fixes his judgement, the evidence exceeds not what we
properly
How could we
know call
thatprobability.”
premise (1)(73-4)
is true?
Perhaps one could know that (1) is true by witnessing a miraculous event. But let’s assume for now that none of us
The general moral seems to be correct: when deciding whether to believe or disbelieve
have ever actually witnessed a miracle. Then it seems that our only evidence for (1) is the testimony of people that
some proposition, we should weigh the evidence for and against it to see whether it makes
do claim
have actually
a miracle.
So, it seems that to see whether we have good reason for believing
thetoproposition
or itswitnessed
negation more
probable.
(1), we have to figure out when we are justified in believing something on the basis of testimony.
How does this sort of general principle fit with our practice of basing beliefs on testimony?
very plausible
This is Hume
one ofhas
theacentral
topics answer:
addressed by Hume. Here’s what he has to say about it:
“we may observe, that there is no species of reasoning more common, more
useful, and even necessary to human life, than that which is derived from the
testimony of men, and the reports of eye-witnesses and spectators. . . . I shall
not dispute about a word. It will be sufficient to observe, that our assurance
in any argument of this kind is derived from no other principle than our
observation of the veracity of human testimony, and of the usual conformity
of facts to the reports of witnesses.” (74)
2.1
Testimony and evidence
The argument from miracles
Hume’s first claim is that we should base belief on the available evidence:
1. There have been miracles.
2. If there have been miracles, God exists.
_____________________________________________
“A wise man, therefore,
proportions his belief to the evidence. . . . He weighs
the opposite experiments:
He considers which side is supported by the greater
C. God exists.
number of experiments: To that side he inclines, with doubt and hesitation;
and when at last he fixes his judgement, the evidence exceeds not what we
properly
How could we
know call
thatprobability.”
premise (1)(73-4)
is true?
Perhaps one could know that (1) is true by witnessing a miraculous event. But let’s assume for now that none of us
The general moral seems to be correct: when deciding whether to believe or disbelieve
have ever actually witnessed a miracle. Then it seems that our only evidence for (1) is the testimony of people that
some proposition, we should weigh the evidence for and against it to see whether it makes
do claim
have actually
a miracle.
So, it seems that to see whether we have good reason for believing
thetoproposition
or itswitnessed
negation more
probable.
(1), we have to figure out when we are justified in believing something on the basis of testimony.
How does this sort of general principle fit with our practice of basing beliefs on testimony?
very plausible
This is Hume
one ofhas
theacentral
topics answer:
addressed by Hume. Here’s what he has to say about it:
“we may observe, that there is no species of reasoning more common, more
useful, and even necessary to human life, than that which is derived from the
testimony of men, and the reports of eye-witnesses and spectators. . . . I shall
not dispute about a word. It will be sufficient to observe, that our assurance
in any argument of this kind is derived from no other principle than our
observation of the veracity of human testimony, and of the usual conformity
of facts to the reports of witnesses.” (74)
Hume’s basic idea seems to be this: we believe things on the basis of testimony because, in the past, we have
found that testimony is normally correct: normally
2 the facts conform to the testimony we receive.
Is Hume right about the fact that we have found testimony to be, usually, correct?
Does this mean that we should always believe whatever we are told?
Pascal situates
the question of miracles within (one part of) the Christian tradition. But
and when at last he fixes his judgement, the evidence exceeds not what we
the question
we call
want
to answer(73-4)
is more general: can miracles play this kind of central
properly
probability.”
role in justifying religious
of any from
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miracles
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1. There
have
been
miracles.
we should
weigh the
evidence for and against it to see whether it makes
whosome
haveproposition,
not themselves
miracles.
2. witnessed
If there have
been miracles, God exists.
the proposition or its negation
more probable.
_____________________________________________
C. Godprinciple
exists. fit with our practice of basing beliefs on testimony?
How does this sort of general
2 plausible
Hume’s
argument against belief in miracles
Hume has a very
answer:
“we may
that there
no species
reasoning
common,
Hume thinks
thatobserve,
they cannot,
andis indeed
thatof no
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person
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base belief in
The argument
miracles
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even necessary
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God on from
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miracles have
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Hethat
says:
testimony of men, and the reports of eye-witnesses and spectators. . . . I shall
1. There have been
miracles.
not dispute
about a word. It will be sufficient to observe, that our assurance
2. If there have
God
exists.
anymiracles,
argument
of this
kind isit derived
from no
other
than our can
“. .in
.been
therefore
we may
establish
as a maxim,
that
no principle
human testimony
_____________________________________________
observation
of as
theto
veracity
anditofa the
conformity
have
such force
prove ofa human
miracle,testimony,
and make
justusual
foundation
for any
C. God exists. of facts to the reports of witnesses.” (74)
system of religion.” (88)
Hume’s basic idea seems to be this: we believe things on the basis of testimony because, in the past, we have
Thisbasic
is Hume’s
conclusion.
now
need to things
understand
his
argument
for it, which
begins
Hume’s
idea seems
to be We
this:
we believe
on the
basis
oftotestimony
because,
in the past, we have
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testimony
is normally
correct:
normally
conform
the testimony
we receive.
2 the facts
with
premises
about the
role ofnormally
perceptual
evidence
and testimony
in the we
forming
found
thatsome
testimony
is normally
correct:
the facts
conform
to the testimony
receive.
of beliefs.
Is Hume right about the fact that we have found testimony to be, usually, correct?
Does this mean that we should always believe whatever we are told? This can’t be right, since we are sometimes
told
contradictory
things.
And, inalways
any case,
Hume
does not
that we should always accept testimony.
Does
this mean that
we should
believe
whatever
wethink
are told?
2.1 Testimony and evidence
No. Testimony is just one piece of evidence among others. And in cases in which testimony contradicts some of
Testimony
just one
piece
of evidence
among
others.
And
cases in
which testimony contradicts some of our
Hume’sis first
we should
base
belief
the in
available
evidence:
our evidence,
weclaim
have is
to that
determine
which
piece
of on
evidence
is stronger:
evidence, we have to determine which piece of evidence is stronger:
“A wise man, therefore, proportions his belief to the evidence. . . . He weighs
the opposite experiments: He considers which side is supported by the greater
number of experiments: To that side he inclines, with doubt and hesitation;
and when at last he fixes his judgement, the evidence exceeds not what we
properly call probability.” (73-4)
general
seems
to be correct: when deciding whether to believe or disbelieve
This The
suggests
themoral
following
rule:
1. There have been miracles.
2. If there have
miracles,
Godestablish
exists. it as a maxim, that no human testimony can
“. . .been
therefore
we may
_____________________________________________
The
from miracles
have such force as
toargument
prove a miracle,
and make it a just foundation for any
C. God exists.
system of religion.”
(88)
1. There have been miracles.
2. If there have been miracles, God exists.
_____________________________________________
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is Hume’s
conclusion.
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now
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understand
argument
for it, which
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to
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on thehis
basis
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because,
in the past, we have
C.be
God
exists.
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premises
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perceptual
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in the we
forming
found
thatsome
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the facts
conform
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receive.
of beliefs.
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mean
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should
always
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whatever
webasis
are told?
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be right,insince
we are
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seems
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we believe
on the
of testimony
the past,
wesometimes
have
told that
contradictory
And,correct:
in any case,
Hume
not
think that
wetestimony
should always
accept testimony.
found
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is normally
thedoes
facts
conform
to the
we receive.
2.1 normally
Testimony
and
evidence
Testimony is just one piece of evidence among others. And in cases in which testimony contradicts some of our
Testimony
is first
just one
piece
of evidence
among
others.
in
cases in
which testimony contradicts some of our
Hume’s
claim
is that
we should
base
belief
onAnd
the
available
evidence:
evidence,
we have
to
determine
which
piece
of evidence
is stronger:
evidence, we have to determine which piece of evidence is stronger:
“A wise man, therefore, proportions his belief to the evidence. . . . He weighs
the opposite experiments: He considers which side is supported by the greater
number of experiments: To that side he inclines, with doubt and hesitation;
and when at last he fixes his judgement, the evidence exceeds not what we
properly call probability.” (73-4)
ThisThis
suggests
the following
rule rule:
about
when
we should,
and should
not, believe
testimony
about some event
The
general
seems
to be
correct:
when deciding
whether
to believe
or disbelieve
suggests
themoral
following
occurring:
some proposition, we should weigh the evidence for and against it to see whether it makes
the proposition or its negation more probable.
We should only believe testimony about the occurrence of some event E if the
Hume’s
principle
aboutthan
testimony
of the
testimony
being
true
is higher
the
probability
of E’s
not occurring.
Howprobability
does this sort
of general
principle
fit
with
our practice
of basing
beliefs
on testimony?
Hume has a very plausible answer:
We should not believe that M happened on the basis of
the testimony unless the following is the case:
“we may observe, that there is no species of reasoning more common, more
useful, and even necessary
to human
life,
than that
which
is derived
The probability
of the
testimony
being
false
< the from the
testimony of men,probability
and the reports
of eye-witnesses and spectators. . . . I shall
of M occurring.
not dispute about a word. It will be sufficient to observe, that our assurance
in any argument of this kind is derived from no other principle than our
observation of the veracity of human testimony, and of the usual conformity
The argument from miracles
1. There have been miracles.
2. If there have been miracles, God exists.
_____________________________________________
C. God exists.
Hume’s basic idea seems to be this: we believe things on the basis of testimony because, in the past, we have
found that testimony is normally correct: normally the facts conform to the testimony we receive.
The argument from miracles
This suggests the following rule about when we should, and should not, believe testimony about some event
1. There have been miracles.
occurring:
2. If there
have
been miracles,
Godisexists.
One
conclusion:
testimony
one, but not the only, source of evidence which we should use
_____________________________________________
when forming a belief. Testimony
is relevant
because
it has a (relatively) high probability
Hume’s principle
about
testimony
C. God exists.
of being true. But, like any evidence, this can be overridden by other sources of evidence
(like, for example,
contrary
testimony)
have giveona the
highbasis
probability
to the negation
We should
not believe
thatwhich
M happened
of
of the proposition
in question.
the testimony
unless the following is the case:
We should onlyThe
believe
testimony
about
the occurrence
of <
some
probability
of the
testimony
being false
the event E if the
2.2
probability of the
testimony
true is about
highermiracles
than the probability of E’s not occurring.
probability
ofbeing
MTestimony
occurring.
We now need to apply these general points about testimony and evidence to the case of
suggests
the
principle
miracles:
HumeThis
applies
this principle
explicitly
to theabout
case
of
miraculous
events:
miracles.
Onefollowing
conclusion
seems
to
follow
immediately:
“That no testimony is sufficient to establish a miracle, unless the testimony
be of such a kind, that its falsehood would be more miraculous, than the fact,
which it endeavors to establish . . . ” (77)
Suppose
we
have testimony
that some
miraculous
event M happened.
Hume is from
say that
not believe
The
problem
forfalsehood
the believer
in miracles
is that
being departures
the we
lawsshould
What it would
mean
for the
of the
testimony
to bemiracles,
“more miraculous”
than the occurrence
of the
M happened
on seem
the basis
the testimony
the following
the case:
of nature,
to beofexactly
the sortsunless
of events
which we isshould
not expect to happen.
relevant event? It would mean that the probability of the testimony being false is even lower than the
As Hume puts it:
probability of the event in question happening. And this is exactly what Hume’s principle about testimony
The probability of the testimony being false < the probability of M occurring.
should lead us to expect.
“A miracle is a violation of the laws of nature; and as a firm and unalterable
1. There have been miracles.
Pascal situates the question of miracles within (one part of) the Christian tradition. But
2. If there
have
been miracles,
Godisexists.
One
conclusion:
testimony
one, but not the only, source of evidence which we should use
_____________________________________________
the question we want to answer is more general: can
miracles
play this
kindtestimony
of central
Hume’s
principle
about
when
forming
a
belief.
Testimony
is
relevant
because
it
has
a
(relatively)
high
probability
The C.
argument
miraclesreligious belief of any sort?
rolefrom
in justifying
God exists.
of being true. But, like any evidence, this can be overridden by other sources of evidence
Wehave
should
believe
that M happened
on the basis of
1. There have
been
(like,
formiracles.
example,
contrary
testimony)
which
givenot
a high
probability
the negation
We
will
focus
on the
question
of whether
miracles
can
justify
the
religioustobeliefs
of people
the testimony unless the following is the case:
of
the
proposition
in
question.
2. If there have
been
miracles,
God
exists.
who
have
not themselves
witnessed miracles.
_____________________________________________
C. God exists. We should only believe testimony about the occurrence
The probability
of theevent
testimony
of some
E if thebeing false < the
2.2 being
Testimony
about
miracles
probability
of
M occurring.
probability of the
true is
higher
than
thein
probability
2 testimony
Hume’s argument
against
belief
miraclesof E’s not occurring.
We now need to apply these general points about testimony and evidence to the case of
suggests
the
principle
miracles:
HumeThis
applies
this thinks
principle
explicitly
to theabout
case
of
miraculous
Hume
that
they
cannot,
and
indeed
that noevents:
rational person would base belief in
miracles.
Onefollowing
conclusion
seems
to
follow
immediately:
God on testimony that miracles have occurred. He says:
Hume’s principle about testimony.
The argument from miracles
“That no testimony is sufficient to establish a miracle, unless the testimony
be
such
a kind,
that its
falsehood
be more
miraculous,
than
the fact,
1. There have
miracles.
“.been
.of. therefore
we may
establish
it aswould
a maxim,
no not
human
testimony
can
We that
should
believe
that M happened
on the basis of th
which
it
endeavors
to
establish
.
.
.
”
(77)
2. If there have
been
miracles,
exists.a miracle, and make
have
such
force asGod
to prove
it a just
foundation
for any
testimony
unless
the following
is the case:
_____________________________________________
system of religion.” (88)
C.
God
exists.
Suppose
we
have testimony
that some
miraculous
event M happened.
Hume is
say
that
not believe th
The
problem
forfalsehood
the believer
in miracles
is that
being
departures
from
the we
lawsshould
The probability
the
testimony
being
What it would
mean
for the
of the
testimony
to bemiracles,
“more miraculous”
thanof
the
occurrence
of
the false < the
M happened
on seem
the basis
the testimony
the following
isshould
the case:
of nature,
to beofexactly
the sortsunless
of events
which weprobability
notofexpect
to happen.
M occurring.
relevant event?
It
would
mean
that
the
probability
of
the
testimony
being
false
is
even
lower
than the
This
is Hume’s
As
Hume
puts it:conclusion. We now need to understand his argument for it, which begins
probability ofwith
the event
in question
happening.
And
this is exactly what Hume’s
principle
testimony
some premises
about
the role
of perceptual
and
in about
the forming
The probability
of the
testimony
being
false < the evidence
probability
of testimony
M occurring.
should lead us
to expect.
of beliefs.
“A miracle is a violation of the laws of nature; and as a firm and unalterable
We now
want
to know
whyestablished
Hume
thinks
thatlaws,
amean
principle
of falsehood
this
sort shows
we are
never
justified
in believing
This
is one
plausible
reading
of what
itthese
would
forproof
the
of
thethat
testimony
to
be “more
miraculous”
th
experience
has
the
against
a
miracle,
from
the
We now
want
to about
knowofwhy
thinks
that a principle of this sort shows that we are never justified in believing
testimony
miracles.
the
occurrence
the Hume
relevant
event.
very
nature
of
the
fact,
is as entire as any argument from experience can
testimony about miracles.
2.1 Testimony and evidence
possibly
be
imagined
. . . There
must be the
a uniform
experience
against
every
To
do
this,
we
need
to
figure
out
how
to
determine
relevant
probabilities:
of
the
testimony
being false,
and of M
We
now
want
to
know
why
Hume
thinks
that
a
principle
of
this
sort
shows
that
we
are
never
justified
in
believing
miraculous
event,
otherwise
the event
would
notprobabilities:
merit that appellation.”
(76To do this,
we need
to
figurethe
outquote
how
to
determine
thediscussed
relevant
the probability
of the testimony being
not
occurring.
Recall
about
evidence
earlier:
about
miracles.
Hume’s
claim
that weevent
should
belief on
the available
7) first
false, testimony
and the
probability
of the isrelevant
notbase
occurring.
Recall
the quoteevidence:
about evidence discussed earlier:
The implied
question
is: could testimony
ever
strong
enough evidence
override
“A wise
man, therefore,
proportions
hisprovide
belief to
the evidence.
. . . He to
weighs
our massive
evidence
in favor of nature’s
following
its side
usualis course
(which
also
evidence
the opposite
experiments:
He considers
which
supported
by is
the
greater
againstnumber
the occurrence
of the miracle)?
of experiments:
To that side he inclines, with doubt and hesitation;
and when at last he fixes his judgement, the evidence exceeds not what we
properly call probability.” (73-4)
2.3 The relevance of religious diversity
The argument from miracles
Hume’s principle about testimony.
1. There have“.been
miracles.
. . therefore
we may establish it as a maxim,
that
no not
human
testimony
can
principle
about
We Hume’s
should
believe
that Mtestimony
happened
on the basis of th
The argument
from
miracles
2. If there have
been
miracles,
exists.a miracle, and make
have
such
force asGod
to prove
it a just
foundation
for any
testimony
unless
the following
is the case:
_____________________________________________
of religion.” (88)
We should not believe that M happened on the basis of
1. There
haveexists.
beensystem
miracles.
C. God
the testimony unless
the following
is testimony
the case: being false < the
The probability
of the
2. If there have been miracles, God exists.
_____________________________________________
probability of M occurring.
This
is
Hume’s
conclusion.
We
now
need
to
understand
his
argument for it, which begins
C. God exists.
The probability of the testimony being false < the
with some premises about the role of perceptual evidence and testimony in the forming
probability of M occurring.
of beliefs.
We now want to know why Hume thinks that a principle of this sort shows that we are never justified in believing
We now
want to about
know why
Hume thinks that a principle of this sort shows that we are never justified in believing
testimony
miracles.
testimony about miracles.
2.1 Testimony and evidence
To do this, we need to figure out how to determine the relevant probabilities: of the testimony being false, and of M
To do this,
we need to
figurethe
outquote
how to
determine
thediscussed
relevant probabilities:
the probability of the testimony being
not occurring.
Recall
about
evidence
earlier:
Hume’s
first claim
that weevent
should
belief on
the available
false, and the
probability
of the isrelevant
notbase
occurring.
Recall
the quoteevidence:
about evidence discussed earlier:
“A wise man, therefore, proportions his belief to the evidence. . . . He weighs
the opposite experiments: He considers which side is supported by the greater
number of experiments: To that side he inclines, with doubt and hesitation;
and when at last he fixes his judgement, the evidence exceeds not what we
properly call probability.” (73-4)
Hume’s ideaThe
seems
to bemoral
this. When
trying to when
figure deciding
out the probability
some event
happening in
general
seems we
to are
be correct:
whether toofbelieve
or disbelieve
Hume’s
idea
seems
to
be
this.
When
we
are
trying
to
figure
out
the
probability
of
some
event
happening
in certain
certain circumstances,
we
ask:
in
the
past,
how
frequently
as
that
event
been
observed
to
occur
in
those
some proposition, we should weigh the evidence for and against it to see whether it makes
circumstances,
we ask:tointhis
thequestion
past, how
frequently
as probability
that event been
to occur in those circumstances?
circumstances?
Our answer
will
give
us the
of theobserved
relevant event.
the proposition
or its negation
more
probable.
Our answer to this question will give us the probability of the relevant event.
How does
this sort whether
of generala principle
fit with
our practice
of basing
beliefs
testimony?
So, for example,
to determine
fair coin flip
will come
up heads,
we ask:
in theonpast,
what percentage
Hume
hascome
a veryupplausible
answer:
of fair coin flips
have
heads? We
find that ½ of them have; so we take the event of the next fair coin
flip coming up head to have a probability of 50%, or 0.5.
“we may observe, that there is no species of reasoning more common, more
But this, Hume thinks, is enough to show us that we ought never to believe testimony regarding miraculous
useful, and even necessary to human life, than that which is derived from the
events.
testimony of men, and the reports of eye-witnesses and spectators. . . . I shall
not dispute about a word. It will be sufficient to observe, that our assurance
in any argument of this kind is derived from no other principle than our
One conclusion: testimony is one, but not the only, source
of evidence
whichabout
we should
use
Hume’s
principle
testimony
The argument when
fromforming
miracles
a belief. Testimony is relevant because it has a (relatively) high probability
of being true. But, like any evidence, this can be overridden by other sources of evidence
We should not believe that M happened on the basis of
1. There have been
miracles.
(like, for example, contrary testimony) which have give a high probability to the negation
the testimony
unless
the following
is the case:
2. If there
have of
been
miracles,
God
exists.
Hume’s
principle
about testimony.
The
argument
from
miracles
the
proposition
in
question.
_____________________________________________
C. God
1. exists.
There have been miracles.
The
the testimony
being false
thebasis of th
Weprobability
should notofbelieve
that M happened
on<the
probability
M occurring.
2. If there have been miracles, God exists.
2.2 Testimony about
miracles of
testimony
unless
the following is the case:
_____________________________________________
C. God exists.
We now
to apply
general
points
aboutout
testimony
evidence
to the
the
casehappening
of
Theand
probability
of
testimony
being
Hume’s idea seems
toneed
be this.
Whenthese
we are
trying
to figure
the probability
of some
event
in false < the
miracles. One
conclusion
seems how
to follow
immediately:
probability
of M occurring.
certain circumstances,
we ask:
in the past,
frequently
as that event
been observed
to occur in those
circumstances? Our answer to this question will give us the probability of the relevant event.
“That no testimony is sufficient to establish a miracle, unless the testimony
be
of such a whether
kind, thata its
falsehood
would
be more
miraculous,
thaninthe
fact,
So, forHume’s
example,
determine
fairwe
coin
will to
come
upout
heads,
we ask:
thesome
past,event
what happening
percentagein certain
ideatoseems
to be this. When
areflip
trying
figure
the probability
of
which
it endeavors
toWe
establish
...½
” (77)
of fair circumstances,
coin flips have
come
upinheads?
find frequently
that
of them
have;
so been
we take
the event
of theinnext
faircircumstances?
coin
we ask:
the past,
how
as that
event
observed
to occur
those
flip coming up head to have a probability of 50%, or 0.5.
Our answer to this question will give us the probability of the relevant event.
The problem for the believer in miracles is that miracles, being departures from the laws
nature,isseem
to betoexactly
thethat
sortswe
of ought
events never
which to
we believe
should not
expect to
happen. miraculous
But this, Humeofthinks,
enough
show us
testimony
regarding
This, Hume
thinks,
is enough
to show us that we ought never to believe testimony regarding miraculous events:
As Hume
puts
it:
events.
“A miracle is a violation of the laws of nature; and as a firm and unalterable
experience has established these laws, the proof against a miracle, from the
very nature of the fact, is as entire as any argument from experience can
possibly be imagined . . . There must be a uniform experience against every
miraculous event, otherwise the event would not merit that appellation.” (767)
Hume’s
point
ismiracles
thatquestion
miracles
always
departures
from
the
ordinary
laws
of nature.
Butordinary
the ordinary
The
implied
is:are
could
testimony
ever provide
strong
enough
evidence
to override
Hume’s
point is
that
are always
departures
from
the
ordinary
laws
of
nature.
But
the
lawslaws
of of nat
regularities
which
have
been
observed
to hold
100%
of
theofcourse
time.
Of
course,
weevidence
have
observed
testimony
our massive
evidence
in favor
ofobserved
nature’s
following
its
usual
(which
also
natureare
are
regularities
which
have
been
to hold
100%
the time.
Ofiscourse,
we not
have
not
against
the
of theofmiracle)?
be correct
100%
ofoccurrence
the
time.100%
Hence,
the
of the
testimony
regarding
a miracle
being false
will always be
observed
testimony
to
be
correct
the probability
time. Hence,
probability
of testimony
regarding
a miracle
than
the probability
thethe
miraculous
event;
and
then it follows
principle
about
testimony tha
being greater
false will
always
be greaterof
than
probability
of the
miraculous
event;from
andHume’s
then it follows
from
Hume’s
we about
shouldtestimony
never accept
testimony.
principle
that the
we should
accept of
the
testimony.
2.3 never
The relevance
religious
diversity
The argument from miracles
1. There have been miracles.
2. If there
have beenfrom
miracles,
God exists.
The argument
miracles
_____________________________________________
C. God
exists.have been miracles.
1. There
2. If there have been miracles, God exists.
_____________________________________________
We should not believe that M happened on the basis of the
Hume’s principle about testimony
testimony unless the following is the case:
We should not believe that M happened on the basis of
The probability of the testimony being false < the
the testimony unless the following is the case:
probability of M occurring.
C. God exists.
The probability of the testimony being false < the
of M
occurring.
Pascal situates the question of miracles within (oneprobability
part of) the
Christian
tradition. But
Hume’s idea seems to be this. When we are trying to figure out the probability of some event happening in certain
the question we want to answer is more general: can miracles play this kind of central
circumstances,
weseems
ask: intothe
past,
how frequently
as that
event out
been
to occur
in those
Hume’srole
idea
bereligious
this. When
we of
areany
trying
to figure
theobserved
probability
of some
event circumstances?
happening in
in justifying
belief
sort?
Our answer
this question we
will ask:
give in
usthe
thepast,
probability
of the relevant
certain to
circumstances,
how frequently
as thatevent.
event been observed to occur in those
We will focus
on the question
of whether
miracles
can
justify the
beliefs
of people
circumstances?
Our answer
to this question
will give
us the
probability
of religious
the relevant
event.
who
havemiracles
not themselves
witnessed
miracles.
Hume’s point
is that
are always
departures
from the ordinary laws of nature. But the ordinary laws of nature
are regularities
which
have
been observed
to hold
100% of
thethe
time.
Of course,
wenature.
have not
testimony
Hume’s point
is that
miracles
are always
departures
from
ordinary
laws of
Butobserved
the ordinary
laws to
of
be correct
of the time. which
Hence,have
the probability
of testimony
miracle
false will
always
be
nature100%
are regularities
been observed
to holdregarding
100% of athe
time.being
Of course,
we have
not
greater
than thetestimony
probability
miraculous
event;
andagainst
then
it follows
from
Hume’s
principleregarding
about testimony
that
Hume’s
belief
in miracles
observed
to of
be2the
correct
100%argument
of
the time.
Hence,
the
probability
of testimony
a miracle
we should
accept
the be
testimony.
being never
false will
always
greater than the probability of the miraculous event; and then it follows from Hume’s
principle about testimony that we should never accept the testimony.
Hume thinks that they cannot, and indeed that no rational person would base belief in
Godconclusion:
on testimony that miracles have occurred. He says:
Hence Hume’s
And this is precisely Hume’s conclusion:
“. . . therefore we may establish it as a maxim, that no human testimony can
have such force as to prove a miracle, and make it a just foundation for any
system of religion.” (88)
On this reading, Hume’s argument depends upon the following assumption:
This is Hume’s conclusion. We now need to understand his argument for it, which begins
with some premises about the role of perceptual evidence and testimony in the forming
The zero probability principle
of beliefs.
If some event has never been observed to occur
before, then the
of itand
occurring
is 0%.
2.1probability
Testimony
evidence
Hume’s principle about testimony
The argument from miracles
1. There have been miracles.
2. If there have been miracles, God exists.
_____________________________________________
C. God exists.
We should not believe that M happened on the basis of
the testimony unless the following is the case:
The probability of the testimony being false < the
probability of M occurring.
On this reading, Hume’s argument depends upon the following assumption:
The zero probability principle
If some event has never been observed to occur
before, then the probability of it occurring is 0%.
This is what enables Hume to conclude that we can never be justified in believing testimony about a miracle,
since, as he plausibly assumes, the probability of the testimony being false will always be > 0.
Interestingly, this principle also seems to be enough to establish a stronger claim: one is never justified in
believing in the existence of miracles, even if one is (or takes oneself to be) an eyewitness. Can you see why?
Perceptual experiences of the world, like testimony, don’t conform to the facts 100% of the time. So, the probability
of a miraculous event M occurring will always, given the above principle about probabilities, be less than the
probability of one’s perceptual experience being illusory, since the latter will always be > 0. Hence, it seems, one
would never be justified in believing in the existence of a miracle, even on the basis of direct perceptual experience.
This might at first seem like a good thing for Hume’s argument: it shows not just that one an never believe in miracles
on the basis of testimony, but also that one can never believe in them for any reason at all!
But in fact this brings out a problem for the zero probability principle.
Hume’s principle about testimony
The argument from miracles
1. There have been miracles.
2. If there have been miracles, God exists.
_____________________________________________
We should not believe that M happened on the basis of
the testimony unless the following is the case:
C. God exists.
The probability of the testimony being false < the
probability of M occurring.
The zero probability principle
If some event has never been observed to occur
before, then the probability of it occurring is 0%.
Perceptual experiences of the world, like testimony, don’t conform to the facts 100% of the time. So, the probability
of a miraculous event M occurring will always, given the above principle about probabilities, be less than the
probability of one’s perceptual experience being illusory, since the latter will always be > 0. Hence, it seems, one
would never be justified in believing in the existence of a miracle, even on the basis of direct perceptual experience.
This might at first seem like a good thing for Hume’s argument: it shows not just that one an never believe in miracles
on the basis of testimony, but also that one can never believe in them for any reason at all!
But in fact this brings out a problem for the zero probability principle.
Consider the following sort of example:
You are a citizen of Pompeii in AD 79, and there is no written record of the tops of
mountains erupting and spewing forth lava. Accordingly, following the zero probability
principle, you regard the chances of such a thing happening as 0%. On the other hand,
you know that your visual experiences have been mistaken in the past, so you regard the
chances of an arbitrary visual experience being illusory as about (say) 1%. Then you have
a very surprising visual experience: black clouds and ash shooting out of nearby Mt.
Vesuvius. What is it rational for you to believe?
Hume’s principle about testimony
The argument from miracles
1. There have been miracles.
2. If there have been miracles, God exists.
_____________________________________________
We should not believe that M happened on the basis of
the testimony unless the following is the case:
C. God exists.
The probability of the testimony being false < the
probability of M occurring.
The zero probability principle
If some event has never been observed to occur
before, then the probability of it occurring is 0%.
Consider the following sort of example:
You are a citizen of Pompeii in AD 79, and there is no written record of the tops of
mountains erupting and spewing forth lava. Accordingly, following the zero probability
principle, you regard the chances of such a thing happening as 0%. On the other hand,
you know that your visual experiences have been mistaken in the past, so you regard the
chances of an arbitrary visual experience being illusory as about (say) 1%. Then you have
a very surprising visual experience: black clouds and ash shooting out of nearby Mt.
Vesuvius. What is it rational for you to believe?
This sort of case seems to show that the zero probability principle is false. Other such examples involve falsification of
well-confirmed scientific theories.
So, if Hume’s argument depends on the zero probability principle, it is a failure. But this doesn’t quite mean that
Hume’s argument is a failure. Sometimes an argument relies on a false premise, but can be fixed by finding another
premise which both avoids the problems with the original one, and still delivers the intended conclusion.
So we should ask: can we come up with another principle, which would avoid these sort of counterexamples while
still delivering the result that Hume wants?
The argument from miracles
1. There have been miracles.
2. If there have been miracles, God exists.
_____________________________________________
C. God exists.
Hume’s principle about testimony
We should not believe that M happened on the basis of
the testimony unless the following is the case:
The probability of the testimony being false < the
probability of M occurring.
So we should ask: can we come up with another principle, which would avoid these sort of counterexamples while
still delivering the result that Hume wants?
It seems that we can. All Hume’s argument needs, it would seem, is the following trio of assumptions:
(a) If some event has never been observed to occur before, then the probability
of it occurring is at most X%.
(b) The probability of a piece of testimony being false is always at least Y%.
(c) Y>X
X does not have to be zero, as the zero probability principle assumes; it is enough for Hume’s argument that it be
some number which is always lower than the probability of testimony being false.
Suppose, for example, that the probability of an event of some type which has never before been observed is at
most 1%, and that there is always at least a 10% chance of some testimony being false. If we assume Hume’s
principle about testimony, would this be enough to deliver the conclusion that we are never justified in believing in
miracles on the basis of testimony?
No, because one can get testimony from multiple witnesses. Suppose that we have three witnesses, each of whom
are 90% reliable, and each independently reports that M has occurred. Then the probability of each witness being
wrong is 10%, but the probability of all three being wrong is only 0.1%. This, by the above measure, would be
enough to make it rational to believe that M happened on the basis of testimony.
The argument from miracles
1. There have been miracles.
2. If there have been miracles, God exists.
_____________________________________________
C. God exists.
Hume’s principle about testimony
We should not believe that M happened on the basis of
the testimony unless the following is the case:
The probability of the testimony being false < the
probability of M occurring.
It seems that we can. All Hume’s argument needs, it would seem, is the following trio of assumptions:
(a) If some event has never been observed to occur before, then the probability
of it occurring is at most X%.
(b) The probability of a piece of testimony being false is always at least Y%.
(c) Y>X
Suppose, for example, that the probability of an event of some type which has never before been observed is at
most 1%, and that there is always at least a 10% chance of some testimony being false. If we assume Hume’s
principle about testimony, would this be enough to deliver the conclusion that we are never justified in believing in
miracles on the basis of testimony?
No, because one can get testimony from multiple witnesses. Suppose that we have three witnesses, each of whom
are 90% reliable, and each independently reports that M has occurred. Then the probability of each witness being
wrong is 10%, but the probability of all three being wrong is only 0.1%. This, by the above measure, would be
enough to make it rational to believe that M happened on the basis of testimony.
So it seems that the possibility of multiple witnesses shows that (a)-(c) are not enough to make Hume’s argument
against justified belief in miracles on the basis of testimony work no matter what values we give to “X” and “Y”.
(Of course, it is important to distinguish between having testimony from multiple witnesses and having testimony
from a single witness who claims there to have been multiple witnesses.)
But what if we have just one witness. In those cases, won’t Hume’s principle about testimony provide a good
argument against the rationality of believing in miracles?
The argument from miracles
1. There have been miracles.
2. If there have been miracles, God exists.
_____________________________________________
C. God exists.
Hume’s principle about testimony
We should not believe that M happened on the basis of
the testimony unless the following is the case:
The probability of the testimony being false < the
probability of M occurring.
But what if we have just one witness. In those cases, won’t Hume’s principle about testimony provide a good
argument against the rationality of believing in miracles?
Even this can be called into question, because there is good reason to doubt whether Hume’s principle about
testimony is itself true.
This principle can sound sort of obvious; but it isn’t, as some examples show. First, what do you think that the
probability of the truth of testimony from the writers of the South Bend Tribune would be?
Let’s suppose that you think that it is quite a reliable paper, and that its testimony is true 99.9% of the time, so that the
probability of its testimony being false is 0.1%.
Now suppose that you read the following in the South Bend Tribune:
“The winning numbers for Powerball this weekend were 1-14-26-33-41-37-4.”
What are the odds of those being the winning numbers for Powerball? Well, the same as the odds of any given
combination being correct, which is 1 in 195,249,054. So the probability of the reported event occurring is
0.0000005121663739%.
So, if Hume’s principle about testimony is correct, one is never justified in believing the lottery results reported in
the paper, or on the local news, etc. But this seems wrong: one can gain justified beliefs about the lottery from your
local paper, even if it is the South Bend Tribune.
You may want to think about how, if at all, Hume’s principle could be modified to avoid these counterexamples.
The argument from miracles
1. There have been miracles.
2. If there have been miracles, God exists.
_____________________________________________
C. God exists.
Hume’s principle about testimony
We should not believe that M happened on the basis of
the testimony unless the following is the case:
The probability of the testimony being false < the
probability of M occurring.
You may want to think about how, if at all, Hume’s principle could be modified to avoid these counterexamples.
If it cannot be fixed, then Hume fails to show that it is never rational to believe in miracles on the basis of testimony.
This, of course, does not show that we are currently rational to believe in miracles on the basis of the sorts of
testimony we might use as evidence. To decide this question, at least three further issues would need investigation.
1. What are the rules which govern rational acceptance of testimony? If Hume’s principle about testimony is not
right, then what is?
2. How good is the evidence for events which seem to be exceptions to the usual natural order? This would involve
historical investigation into questions like the following: How many witnesses were there? How reliable were those
witnesses? Did they have anything to gain by lying? Etc.
3. When is good evidence that some event is an exception to the usual natural order also good evidence of
supernatural intervention?
These are all very difficult questions to answer. What I think the discussion of Hume shows is that to decide the
relevance of miracles to religious belief, questions like these are the important ones. There is no argument - at least
no obvious argument - of the sort Hume sought against belief in miracles.