Three Forms of Naturalism
by Penelope Maddy
Naturalism and normativity
Naturalists like Quine do not see (most)
philosophical questions as
fundamentally confused (like Kant,
Wittgenstein, and Carnap do.) Rather,
they are questions for which no scientific
methods have yet been developed.
If traditional philosophical questions can
be answered, they will be answered by
methods developed within the natural
sciences. Philosophical questions about
proper scientific method will involve the
scientific study of science itself.
For Quine, the normative dimension of
philosophy remains; it just doesn’t issue
from an extra scientific perspective.
Neurath’s Boat provides the proper
imagery. If scientists are the ones
piloting the boat, then philosophers are
the ones repairing and improving it.
Holism and the maxim of minimum
mutilation
Quine subscribed to a holistic account of
both meaning and confirmation. He was
deeply influenced by Pierre Duhem, an
early 20th century French physicist who
said:
The physicist can never subject an
isolated hypothesis to experimental test,
but only a whole group of hypotheses;
when the experiment is in disagreement
with his predictions, what he learns is
that at least one of the hypotheses
constituting this group is unacceptable
and ought to be modified; but the
experiment does not designate which
one should be changed.
This is idea perfectly familiar to the
logician as well. Indirect proof, or
reduction ad absurdum says that if a
group of sentences jointly imply a
contradiction, then at least one of these
sentences will have to be rejected. It
doesn’t say which one.
For example:
Matthew is an atheist.
Atheists go to hell.
Matthew is my friend.
My friends don’t go to hell.
Matthew both is and isn’t going to
hell.
Rejecting any one of these claims would
make the contradiction go away.
Quine’s principle of minimal mutilation
means that we reject the one that would
do the least damage to our web of
belief.
Holism and Skepticism
Since there are various ways to mutilate
minimally, Quinean holism seems like a
concession to epistemological
skepticism, but Quine’s answer to this is
that, at least with respect to theoretical
science, is that it makes no more sense
to be skeptical of molecules then it does
to be skeptical about the large scale
physical objects that molecules
allegedly compose.
Recall that the extreme empiricist
attends to the senses, and all we get
there is
“variformed and varicolored visual
patches, varitextured and
varitemperatured tactile feels, and an
assortment of tones, tastes, smells and
other odds and ends; desks… are no
more to be found among these data
than molecules.
So, the point is that unless you are
prepared to advocate a common sense
direct realism, itself immune to any
realistic considerations of how humans
learn, there really isn’t a legitimate
alternative being offered by the skeptic.
Having noted that man has no evidence
for the existence of bodies beyond the
fact that their assumption helps him
organize his experience, we should
have done well, instead of disclaiming
the evidence for the existence of bodies
to conclude: such then, at bottom, is
what evidence is, both for ordinary
bodies and for molecules.
Quine’s Naturalism applied to Logic and
Mathematics
Since Quine claims that all statements
are in principle revisable, this would
apparently apply to both logical
principles and to mathematics as well.
For example, in logic the law of the
excluded middle
P v ~P
is a tautology, and it is difficult to see
how it could ever be false. But, it is
actually a principle that is denied in
various “deviant” logics.
(For example, in fuzzy logic, the law of
the excluded middle is false because
fuzzy logic countenances degrees of
truth and falsity. In FL it is not the case
that P is either true or false, but rather
all statements are both true and false to
some degree. A completely true
statement is true to degree 1 and false
to degree 0. But a pretty true statement
is true to degree .7 and false to degree
.3)
Similarly, Quine believes that even
simple mathematical equations are in
principle revisable. Our sense that it is
just logically impossible for, say, a prime
number to be divisible by 10 is due to
the fact that that it is a core truth in
mathematics, which could not be
changed without dramatic revisions to
the rest of mathematics.
Post Quinean Naturalism
Maddy identifies three distinct takes on
mathematics that may still be properly
identified as naturalistic:
Quine: All knowledge is empirical,
sensory driven, knowledge, and
mathematics qualifies only insofar as it
contributes to it. Mathematics not useful
in science doesn’t count.
 Reason: Mathematics not useful in
science isn’t subject to revision on
empirical grounds.
Burgess: All knowledge is either
empirical or mathematical. Mathematics
not useful in science does count as
knowledge in its own right.
 Reason: You can’t banish
something from the circle of
knowledge that is “our very model of
a progressive and brilliantly
successful cognitive endeavor.”
Maddy: Mathematics only counts as
knowledge to the extent that it serves
empirical science. However,
mathematics that does not currently
serve empirical science should still be
taken seriously in science.
 Reason: History has shown that
mathematics with no apparent
application often does find critical
application.
The Quinean perspective is typically
regarded as extremist, and it is
important to see why, and why this
extremism might be regarded as
appealing. If we follow Burgess and
include mathematics that is immune
from any form of empirical criteria, then
the question immediately arises:
Why should we not include other
endeavors, for example astrology and
theology, as part of science?
Quine: Because astrology and theology
are not responsive to empirical criteria.
Maddy: Because most parts of
astrology and theology do not respond
to empirical criteria, and history has not
shown any part of them that do to be
scientifically useful.
Burgess: Theology and astrology do not
display the cognitive rigor we associate
with both mathematics and science.
Logic
Quine seems to waffle on the status of
logic. There are two contradictory
positions that have been attributed to
him:
 Logic is theoretically revisable on
sensory grounds, and therefore part
of scientific knowledge.
 Logic is immune to revision on
sensory grounds, and is therefore
not part of scientific knowledge.
Notice, that the Quinean criterion for
what counts as knowledge isn’t at issue
here. The question is just whether logic
meets that criterion.
Burgess, since he includes
mathematical knowledge despite being
immune to sensory revision, is free to
think of all logic as purely conceptual as
well without compromising it’s status as
scientific knowledge.
Maddy regards logic as essentially
empirical, though not necessarily
knowledge that comes from individual
experience. Her view may be
understood as naturalized Kantian, or
Darwinian, in that she assumes that
much rudimentary logic is built into our
cognitive architecture, but that the very
reason for this is that it has proven
useful for rudimentary representations of
the world. Arguments for deviant logics
(such as the fuzzy logic noted above)
will ultimately involve the claim that they
are more conducive to higher level
scientific inquiry.
Mathematics and the Scientific Study of
Science
We can also discern three distinct takes
on the normative study of scientific
method.
Quine places particular emphasis on
Ockham’s Razor, which is basically the
requirement that we do not needlessly
multiply entities. If a smaller, simpler set
of assumptions does the same
theoretical work as a larger more
complicated set of assumptions, we
should automatically prefer the former.
(Notice that there is a way of
understanding this preference that is not
open to the naturalist, and which neither
of these philosophers would adopt.
Specifically, it is the idea that we should
pursue simpler theories whenever
possible because simpler theories are
inherently more likely to be true, or, put
differently, reality itself is not
unnecessarily complicated. A naturalist
may argue that simpler scientific
theories have, historically, born more
fruit than unnecessarily complicated
ones, but they can not claim to know
that there is an inherent economy to the
way the world is put together.)
Hence, Quine accepts abstract
mathematical objects in science only
because they have been proven
scientifically useful and no one has
shown how to get rid of them. But he
has strong nominalist tendencies and
believes that if we could dispense with
mathematical objects and continue to
meet the predictive standards of science
then we should do so.
Burgess, on the other hand, argues on
empirical grounds that working scientists
do not attach a great deal of importance
to economy. They are in his view,
happy to multiply entities of all sorts if
they increase power and freedom
without compromising rigor.
Maddy, on the other hand, takes issue
with Quinean holism. You’ll recall that in
the previous article Maddy pointed out
that scientists actually do accept an
internal split level verification process
that allows for early predictive success
to be understood instrumentally, some
robust long term predictive success to
be interpreted realistically, and also
some assumptions, like the continuity of
space and time, to be interpreted
instrumentally despite meeting the
strongest predictive standards.
Here Maddy points out that working
scientists do not buy into the holistic
picture of confirmation and
disconfirmation. They remain
dissatisfied with predictive success as a
basis for realistic interpretation until a
more direct method of confirmation has
been established and carried out. Very
often this depends on defining
procedures and building machines that
can be acceptably described as
detecting the presence of the entities
under question, rather than simply
making accurate predictions on the
assumption that they exist. A proper
account of scientific method should
make sense of that.
The Indispensability Argument
The indispensability argument is simply
that we must accept mathematical
entities in our ontology because without
them science would make no sense.
Quine would be happy if it could be
shown that they are in fact dispensable.
Burgess thinks they are indispensable,
but for the simple reason that he
includes mathematics within science, so
this could be immune to refutation
(which is not good).
Maddy rejecting radical holism, claims
that theoretical indispensability of
mathematics is not enough to commit us
to mathematical objects. As a matter of
practice, scientists do withhold their
assent from theories that are merely
predictive, but which resist detection
through more or less direct causal
interaction.