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curred.
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If you already accept that the world is fundamentally physical, nothing
18
in the Libet experiments or their successors should have much of an influ-
19
ence on your attitude toward free will. You weren’t going to believe in lib-
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ertarian free will anyway, and these experiments have no bearing on one’s
21
stance toward compatibilism. Our brains are messy places, with many small
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subsystems churning along beneath the surface, only occasionally poking
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their way up into our conscious attention. There is no question that we
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sometimes make decisions unconsciously, whether it’s steering our car on
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the way to work or turning onto our side while we sleep. There’s also no
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question that other decisions, like whether to write a book and whether to
27
include a discussion of downward causation in that book, are essentially
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conscious ones. There are fascinating detailed questions that are worth ad-
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dressing about the specific ways in which our brain goes about its business,
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but none of that alters the basic truth that we are collections of elementary
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particles interacting through the rules of the Core Theory. And it’s okay to
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talk about us as human beings making decisions.
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If you accept the universal applicability of the laws of nature, and therefore
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deny libertarian freedom, the argument between compatibilists and
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incompatibilists can seem a bit tiresome. We basically agree on what’s
01
happening— particles obeying the laws of physics, and a macroscopic de-
02
scription of people making choices— and whether we decide to label it “free
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will” might not seem like the most important question.
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Where the issue becomes more than merely academic is when we con-
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front the notions of blame and responsibility. Much of our legal system, and
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much of the way we navigate the waters of our social environment, hinges
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on the idea that individuals are largely responsible for their actions. At ex-
08
treme levels of free- will denial, the idea of “responsibility” is as problematic
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as that of human choice. How can we assign credit or blame if people don’t
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choose their own actions? And if we can’t do that, what is the role of pun-
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ishment or reward?
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Poetic naturalists and other compatibilists don’t need to face up to these
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questions, since they accept the reality of human volition, and therefore
14
have no difficulty in attributing responsibility or blame. There are cases that
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are not so clear, however.
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We attribute reality to our ability to make choices because thinking that
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way provides the best description we know of for the human- scale world. In
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some circumstances, though, that ability seems to be absent, or at least
19
downgraded. One well- known example involved an anonymous patient in
20
Texas who developed a brain tumor after being operated on to help alleviate
21
his epilepsy. Once the tumor occurred, the patient started exhibiting symp-
22
toms of Klüver- Bucy syndrome, a disease that appears in rhesus monkeys
23
but is very rare in humans. Among the symptoms are hyperphagia (exces-
24
sive appetite and eating) and hypersexuality, including compulsive mastur-
25
bation.
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Eventually, the patient started downloading child pornography, which
27
led to his arrest. At his trial, neurosurgeon Orrin Devinsky testified that
28
the patient was not actually in control of his actions— he lacked free will.
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His compulsion to download pornography, in Devinsky’s view, could be
30
completely attributed to the effects of his previous surgery, leaving him
31
without any volition in the matter. The court disagreed, and found him
32
guilty, although he received a relatively light sentence. One of the argu-
33
ments against him was that he was able to avoid pornography when he was
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at work, so he evidently was able to exert some degree of control over his
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own actions.
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What matters here is not the extent to which this particular patient
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actually lost control over his choices, but the fact that such loss is possible.
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What that does to our notions of personal responsibility is a pressing real-
04
world question, not an academic abstraction.
05
If our belief in free will is predicated on the idea that “agents making
06
choices” is part of the best theory we have of human behavior, then the
07
existence of a better and more predictive understanding could undermine
08
that belief. To the extent that neuroscience becomes better and better at
09
predicting what we will do without reference to our personal volition, it
10
will be less and less appropriate to treat people as freely acting agents. Pre-
11
destination will become part of our real world.
12
It doesn’t seem likely, however. Most people do maintain a certain de-
13
gree of volition and autonomy, not to mention a complexity of cognitive
14
functioning that makes predicting their future actions infeasible in prac-
15
tice. There are gray areas— drug addiction is an obvious case where volition
16
can be undermined, even before we go all the way to considering tumors
17
and explicit brain damage. This is a subject in which the basics are far from
18
settled, and much of the important science has yet to be established. What
19
seems clear is that we should base our ideas about personal responsibility
20
on the best possible understanding of how the brain works that we can pos-
21
sibly achieve, and be willing to update those ideas whenever the data call
22
for it.
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P A R t S I x
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C A R I ng
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01
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Three Billion Heartbeats
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C
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arl Sagan, who introduced so many people to the wonders of the
14
cosmos, died in 1996. At an event in 2003, his wife, Ann Druyan,
15
was asked about him. Her response is worth quoting at length:
16
17
When my husband died, because he was so famous and
18
known for not being a believer, many people would come up to
19
me— it still sometimes happens— and ask me if Carl changed at
20
the end and converted to a belief in an afterlife. They also fre-
21
quently ask me if I think I will see him again.
22
Carl faced his death with unflagging courage and never
23
sought refuge in illusions. The tragedy was that we knew we
24
would never see each other again. I don’t ever expect to be re-
25
united with Carl. But, the great thing is that when we were to-
26
gether, for nearly twenty years, we lived with a vivid appreciation
27
of how brief and precious life is. We never trivialized the mean-
28
ing of death by pretending it was anything other than a final
29
parting.
30
Every single moment that we were alive and we were together
31
was miraculous— not miraculous in the sense of inexplicable or
32
supernatural. We knew we were beneficiaries of chance. . . . That
33
pure chance could be so generous and so kind. . . . That we could
34
find each other, as Carl wrote so beautifully in Cosmos, you
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know, in the vastness of space and the immensity of time. . . .
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That we could be together for twenty years. That is something
02
which sustains me and it’s much more meaningful. . . .
03
The way he treated me and the way I treated him, the way we
04
took care of each other and our family, while he lived. That is so
05
much more important than the idea I will see him someday. I
06
don’t think I’ll ever see Carl again. But I saw him. We saw each
07
other. We found each other in the cosmos, and that was won-
08
derful.
09
10
There are few issues of greater importance than the question of whether
11
our existence continues on after we die. I believe in naturalism, not because
12
I would prefer it to be true, but because I think it provides the best account
13
of the world we see. The implications of naturalism are in many ways uplift-
14
ing and liberating, but the absence of an afterlife is not one of those ways.
15
It would be nice to keep on living in some fashion, assuming my personal
16
continuation would be relatively pleasant, rather than being tortured by
17
ornery demons. Perhaps not for eternity, but I can easily imagine keeping
18
things interesting for a few hundred thousand years. Regrettably, that’s not
19
the way the evidence points.
20
The longing for life to continue beyond our natural span of years is part
21
of a deeper human impulse: the hope, and expectation, that our lives mean
22
something, that there is some point to it all. The notion of “reasons why” is
23
often useful in our human- scale world, but might not apply when we start
24
talking about the origin of the universe or the nature of the laws of physics.
25
Does it apply to our lives? Are there reasons why we are here, why things
26
happen the way they do?
27
It takes courage to face up to the finitude of our lives, and even more
28
courage to admit the limits of purpose in our existence. The most telling
29
part of Druyan’s reflection is not the acknowledgment that she won’t see
30
Carl again, but where she affirms that it was pure chance that they ever
31
found each other in the first place.
32
Our finite life- span reminds us that human beings are part of nature,
33
not apart from it. Physicist Geoffrey West has studied a remarkable series
34
of scaling laws in a wide range of complex systems. These scaling laws are
35S
patterns that describe how one feature of a system responds as some other
36N
feature is changed. For example, in mammals, the expected lifetime scales
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as the average mass of an individual to the 1/ 4 power. That means that a
01
mammalian species that is sixteen times heavier will live twice as long as a
02
smaller species. But at the same time, the interval between heartbeats in
03
mammalian species also scales as their mass to the 1/ 4 power. As a result,
04
the two effects cancel out, and the number of heartbeats per typical lifetime
05
is roughly the same for all mammals— about 1.5 billion heartbeats.
06
A typical human heart beats between sixty and a hundred times a min-
07
ute. In the modern world, where we are the beneficiaries of advanced med-
08
icine and nut
rition, humans live on average for about twice as long as West’s
09
scaling laws would predict. Call it 3 billion heartbeats.
10
Three billion isn’t such a big number. What are you going to do with
11
your heartbeats?
12
13
•
14
Ideas like “meaning” and “morality” and “purpose” are nowhere to be found
15
in the Core Theory of quantum fields, the physics underlying our everyday
16
lives. The same could be said about “bathtubs” and “novels” and “the rules
17
of basketball.” That doesn’t prevent these ideas from being real— they each
18
play an essential role in a successful higher- level emergent theory of the
19
world. The same goes for meaning, morality, and purpose. They aren’t built
20
into the architecture of the universe; they emerge as ways of talking about
21
our human- scale environment.
22
But there is a difference; the search for meaning is not another kind of
23
science. In science we want to describe the world as efficiently and accu-
24
rately as possible. The quest for a good life isn’t like that: it’s about evaluat-
25
ing the world, passing judgment on the way things are and could be. We
26
want to be able to point to different possible events and say, “That’s a wor-
27
thy goal to strive for,” or “That’s the way we ought to behave.” Science
28
couldn’t care less about such judgments.
29
The source of these values isn’t the outside world; it’s inside us. We’re
30
part of the world, but we’ve seen that the best way to talk about ourselves is
31
as thinking, purposeful agents who can make choices. One of those choices,
32
unavoidably, is what kind of life we want to live.
33
We’re not used to thinking that way. Our folk ontology treats meaning
34
as something wholly different from the physical stuff of the world. It might
S35
be given by God, or inherent in life’s spiritual dimension, or part of a
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teleological inclination built into the universe itself, or part of an ineffable,
02
transcendent aspect of reality. Poetic naturalism rejects all of those possi-
03
bilities, and asks us to take the dramatic step of viewing meaning in the
04
same way we view other concepts that human beings invent to talk about
05
the universe.
06
•
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The Big Picture Page 65