I received a letter from a listener last week. Some of you might
remember the comment that I made about four or five weeks ago that it's
impossible for science to prove that there is no soul. This gentleman was
a bit bothered because he felt I was speaking in a vacuum, as it were, and
I really didn't know what I was talking about, and making a comment like
that not only misleads my listeners into having a false sense of
confidence about this issue, but also to those who know better it makes me
a little bit foolish.
Let me give you a couple of points that he made and then I'll give you
my response because I stand fully behind what I said earlier. He mentions
that I made this comment that science would never be able to disprove the
existence of the soul or the immaterial mind then he quotes Christian
philosopher Mortimer Adler. Many of you have probably heard his name. He's
written some fine books. He says that Adler disagrees with me in a
particular book that Adler wrote, Intellect: Mind Over Matter. "Adler
investigates the body-mind problem from a Christian philosophical
perspective. He prefers to call the soul or immaterial mind the intellect.
And he agrees with people like J.P. Moreland that the brain is a necessary
but insufficient condition to explain the mind." In other words, the
brain works together with the mind, but it's something different than the
mind. It has to be there for the mind to work. Although Moreland doesn't
say that entirely, he does say there's a connection. But it is something
different from the mind, which would be my view.
The writer goes on to say, "[Adler] goes on a step further and
says that if science is ever able to produce a machine that can
conceptualize on a conversational level it will prove that the brain is
sufficient to explain the mind and therefore do away with the necessity of
postulating an immaterial mind." Adler doesn't believe this is
possible, but the way to disprove the existence of the mind and therefore
undercut the Christian position is to produce a machine that can
conceptualize on a conversational level. And if it can do that then it
will do what we think it takes a mind to do. That would prove that a mind
is not necessary and therefore, by inference, would prove that human minds
don't exist and Christianity would be discredited.
The writer notes that "Adler spends some time explaining why
conceptualization is the premier attribute of the human mind and why the
experiencing of emotion is of no consequence, not the attribute of
self-awareness." This is an important point. "The reason I'm
writing this is because you made your grand pronouncement that science
will never be able to disprove the soul without giving any indication that
you are aware of the implications of quantum physics, or of the progress
in artificial intelligence and the neurological sciences. Aside from the
fact that the onus of proving a proposition is on the person who makes it
[presumably me in this case], and certainly the existence of the soul is
not proved, it appears contrary to your assertion that this is a
metaphysical idea that at least theoretically can be disproved by science.
Adler points out that Christians would probably not accept this proof and
would go on as if nothing had happened. But he knows that the game would
be up and Christianity would never again be what it was."
He concludes his letter, "I hope you will [respond on the air]
because this kind of statement in a vacuum, so to speak, convinces
knowledgeable listeners that you haven't a clue as to what you're talking
about, and of course this contradicts the very premise of your show. Lest
you think I'm some kind of rabid physicalist, I am a Zen Buddhist with a
grat respect for the Christian religion even though I consider dualism to
be a profound error." And it's signed "respectfully."
I would like to take a few moments and hopefully convince you that I'm
not speaking in a vacuum and that I do know what I'm talking about. But I
also want to give you some tools of thinking to help put down this broad
concern. The concern is that because of the progress of neurological
sciences and computer technology and the idea of artifical intelligence
(I'm going to set the quantum mechanics issue aside for today because it's
a separate issue) that we're actually getting close to a machine that can
actually think. Once we do that, once we make a machine that can actually
think and, in Adler's words "conceptualize on a conversational
level," then we will have proven away the existence of the soul. When
the soul is gone, Christianity is gone and our position is ultimately
refuted. My response is you don't have to be frightened of that for a
number of reasons.
First, my view that science is incapable of proving that souls don't
exist is hard to escape given the current definition of science. That
definition is based on a materialistic view of the world called
naturalism. Science deals with physical things governed by physcial laws.
According to this definition, when the writer started talking about
non-physical things he's talking about theology or philosophy, but he's
not talking about science. Modern science deals only with the physical
universe of cause and effect, governed by natural laws in a metaphysically
closed system. By very definition, science cannot address itself directly
to the question of whether non-physical things like souls exist or not.
Such a question is outside its capabilities, as science is now currently
defined. Some other method is necessary.
It's as if the scientist is attempting to say, "We don't see
invisible things; therefore invisible things aren't there." But one
can't see invisible things precisely because they're invisible. Of course
you wouldn't be able to physically measure a non-physical thing. Science
has a tendency of assuming something doesn't exist because it can't
measure it. But this approach simply is circular and, therefore, false.
Philosopher Dr. Greg Bahnsen calls this the "Crackers in the
Pantry Fallacy." To answer the question "Are there crackers in
the pantry?" one need only go look. But not everything is proven in
the same way. This is a physicalist response; it tests the existence of
physical things. But a soul by definition is not a physical thing,
therefore you can't "go look" for it in a physical kind of way.
This was my principle point in the comment quoted. He wrote
"Contrary to your assertion, this is a metaphysical idea that, at
least theoretically, can be disproved by science." I disagree.
Metaphysical arguments can't be disproved by science, even theoretically,
precisely because they're meta-physical. They transcend the physical
It's like trying to weigh a chicken with a yardstick. Yardsticks don't
give weight; they give length. If you said your chicken weighed 27 inches,
you'd be speaking nonsense. It's called a category error. Yardsticks
simply weren't made to do that sort of thing. That's my point. Science,
strictly speaking, is not even capable of testing for souls, so how can it
disprove the existence of souls? It can't.
Now on to Mr. Adler's thoughts, and let me quote the letter writer
because the wording is important: "If science is ever able to produce
a machine that can conceptualize on a conversational level it will prove
that the physical brain is sufficient to explain the mind, and thereby do
away with the necessity of postulating an immaterial mind....The
experiencing of emotion is of no consequence, nor even the attribute of
First, when a dualist -- one who believes there are two things that
make a human being, a body and a soul -- when a dualist speaks of the
existence of a soul he means something much more than the ability to
"conceptualize on a conversational level," and any attempt to
address the mind/body problem in this truncated fashion misses the mark
If the goal is to somehow prove that the brain and physical nervous
system, etc., are fully capable of explaining what we believe the soul
does, that the mind is really nothing more nor less than a physical brain,
then he's got to go the distance. His alternate model has to explain it
all, not just one aspect.
To the contrary, the experiencing of emotion and the attribute of
self-awareness is of tremendous consequence because these are both
critical attributes of the mental life that require an explanation from
the physicalist. These simply cannot be dismissed with a wave of the hand,
nor can one dismiss other mental attributes. Does this machine hold
beliefs about things? Does it have intentions and purposings? Does it
freely will to do things? Does it feel pain or fear? Does it experience
the taste of a strawberry or feel the frustration of unrequited sexual
If this machine model of mind cannot actually do these things -- not
imitate them; a mere imitation won't do -- then it does not do what human
minds do. And if it does not account for all of the details of the mental
life of a human soul then it does not "do away with the necessity of
postulating an immaterial mind." On the contrary, when we look at all
of the details and ask the question, "What view best explains the
evidence?", the idea of an immaterial mind does a better job of
explaining the vast landscape of mental experience than does the
Secondly, "if/then" assertions ("If science is ever able
to produce a machine that can conceptualize on a conversational level,
[then] it will prove that the physical brain is sufficient to explain the
mind.") can be true conditionals but still be meaningless in the face
of a category fallacy. The conditional statement "If I was a trolley
car, then I'd have wheels," is true but useless; you're not a trolley
car and you'll never be one, not even theoretically. Adler's statement
about machines and minds is much like the statement, "If I can show
you an eighth note that's colored blue, then I will have proven that
musical notes have color." That's true enough, as far as it goes, but
such a statement doesn't change one whit the fact that musical notes are
not colored things.
The same category fallacy applies to this issue of the mind. A moment's
reflection will demonstrate that mental states simply are not physical
things. When we contemplate our own mental life, we are aware of thoughts,
beliefs, sensations, yet we're not the least bit tempted to believe they
are the sorts of things that have weight, texture, size or extension into
My argument is that these are precisely the kinds of things machines
can never do by very nature. Machines are material by nature; mental
states are immaterial by nature. And no re-ordering of mechanical parts is
going to make emotion and ideas and desires and thoughts pop into
existence from machinery.
So first, science by its very nature can't disprove a soul's existence
because science deals with the physical and is not equipped to measure the
Second, a conversation machine is not enough. One would have to create
a machine that could actually do -- not imitate-but actually do --
everything a soul does.
Third, that will never happen because of a fundamental category
fallacy: physical things accomplish physical effects, and the mind's
functions are not physical, therefore a physical machine will not be able
to do what a mind does.
With all of that said, I'm going to give you the farm. I'll concede,
for the sake of argument, everything I've refuted up until now -- I'll say
that science can deal with this, that a physical machine can actually
produce non-physical things like thoughts and intentions, and that it
could do every little thing that a human soul could do. What then? What
would that prove about human souls? Absolutely nothing.
And this brings me to my final criticism of this reasoning. Even if I
granted this fabulous machine, a machine that had every single
characteristic of a human being's mental life, if I granted the farm on
this one, it would prove absolutely nothing regarding the existence of a
If a machine was invented that could conceptualize on a conversational
level, a machine that could hold beliefs, have intentions and purposings,
freely will to do things, feel pain and fear, experience the taste of a
strawberry and feel sexual frustration, the only thing it would prove is
that a machine could understand, feel, think, desire, and get horney. It
proves something about machines; it proves nothing what-so-ever about
It may prove that it's possible for a machine to feel through its
machinery what a human being already feels through his soul. But it would
not prove that a human being is a mere machine. It would not prove that a
human soul doesn't exist.
Actually, it might prove another thing (and this I got from a Star Trek
episode, though philosopher Richard Swinburne argues this way, too). If a
machine can be made to do all the things a human can, it may prove not
that men don't have souls, but that machines do have souls. Once again, it
would not prove that human souls don't exist. In fact, it wouldn't even
speak to the issue.
This is a serious flaw and I'm a bit stunned that someone of Adler's
stature has made this mistake. To "prove that the physical brain is
sufficient to explain the mind and thereby do away with the necessity of
postulating an immaterial mind," does not lead inexorably to
"human minds don't exist."
This is simply a non-sequitur. The second does not follow from the
first. To suggest that the shaking house (to use a timely illustration)
could have been explained by a large truck driving by does not prove that
the truck shook the house, not an earthquake. The suggestion merely
identifies the range of possible explanations. Even if a thing is a
possible explanation, it doesn't follow that it's a necessary explanation
or even the best explanation. That's an entirely different question. An
alternate explanation, even a viable one, simply is not a refutation of
the first position. And that's Adler's mistake.
As you can see, my prior statement was not made in a vacuum, as was