Naturalism and the A Priori
by Penelope Maddy
Kant on transcendental illusions
 Philosophers milking the he-goat.
 “The light dove, cleaving the air in
her free flight, and feeling its
resistance might imagine that its
flight would be still easier in empty
space.”
Locke
 Representational theory of
perception.
 Truth as “conformity” or
correspondence of perception to
external reality.
 Resultant skepticism
Mind
Matte
r
(The picture above actually does not
capture Locke’s theory correctly,
because on Locke’s view the greenness
of the tree is a secondary quality, which
is not a quality of the tree itself, but
present in the mind only. On the other
hand, the shape and size of the tree are
primary qualities that exist in the world
itself.)
Berkeley’s Idealism
 Solves skepticism by elimination of
extra-mental world.
 Objects become collections of
sensations.
 God is the source of stability,
objectivity.
Kant’s Transcendental Idealism
Basic Picture
Private Experience
Public Phenomena
Noumena
C
a
t
e
g
o
r
i
e
s
Space,
Time,
Causation,
etc.
?
Kant resolved the problem of Skepticism
by allowing that there is no
correspondence to the reality beyond
experience, what Kant referred to as the
noumenon. Space and time, however,
are not properly conceived as aspects of
the noumenon. Rather, they are what
Kant calls a priori forms of intuition.
Maddy gives two different readings of
the Kantian scheme:
Harsh Reading
 Heat, color, taste, space, time, and
causation are all appearance, and no
part of external reality.
 External reality is completely
unknowable, however it affects our
senses to cause the appearances.
We call this the harsh reading because
it is incoherent. External reality is at the
same time represented as unknowable,
and known to produce our experiences.
The relation between the noumenon and
our experiences would appear to be
causal, even though causation is not a
relation that it makes sense to apply to
the noumenon.
Benign Reading
Although space and time are not
aspects of the noumenon, they are
distinct from sensations of color, taste,
heat, etc. in that they provide the form of
our experience and understanding, not
the content.
The content of our experiences
changes, but the form does not, and this
is why space and time are properly
regarded as real and external to us,
despite the fact that they are not
aspects of the noumenon.
Maddy makes this point very well: it is a
misreading of Kant to think that on his
view there are empirical objects and
transcendental objects, where the latter
gives rise to, or causes the former.
Rather, there is an empirical and
transcendental point of view.
So, to take Maddy’s example: a
rainbow may be described as a visual
illusion, where the underlying reality is
the interaction of electromagnetic
radiation and water. But even EMR and
H20 are perceptual objects when viewed
from a transcendental point of view.
Kant, then, is, like Locke, an empirical
realist in the sense that science
investigates an objective, external reality
conditioned by space, time, and
causation. This reality appears to
everyone in the same way, and is not
properly described as subjective
However, he is a transcendental idealist
in that he allows that even space and
time are something that we impose, they
do not correspond to an external reality.
(Here he differs from Locke)
Empirical
Realist
Kant
(Phenomenal)
Idealist
Berkeley
Locke (For
Secondary Qualities)
Transcendental
Locke (For
Kant (Noumenal)
Primary Qualities)
The main problem for the benign
reading is to make sense of the relation
between the noumena and phenomena.
Kant explicitly repudiates the idea that
transcendental objects cause empirical
objects, since both the concept of
“object” and the concept of “cause” do
not have any application in the
transcendental realm.
This really seems to lead Kant directly to
the kind of skepticism that plagued
Locke. Kant is put in the position of
saying that we humans have a hard time
understanding how our perceptions
could arise from nothing, but in the end
there is nothing at all we can know
about this noumenon.
Kant’s reply to this objection is,
essentially: don’t give me any shit.
…For what is demanded is that we
should be able to know things, and
therefore intuit them, without sense, and
therefore that we should have a faculty
of knowledge altogether different than
the human, and this not only in degree
but as regards intuition likewise in kindin other words, that we should be not
men, but beings of whom we are unable
to say whether they are even possible,
much less how they are constituted.
One major problem for Kant scholarship,
though, is that Kant does not really
abide by this restriction on our
knowledge of the noumenon. For
example Kant’s notion of the self, what
he calls the “transcendental unity of
apperception” seems to be a noumenal
object, or principle of precisely the sort
that he regards above to be incoherent.
The main problem for the benign
reading
Kant’s scheme allows for scientific
inquiry within a certain a priori
conception of space and time. It does
not necessarily conflict with the idea that
science discovers a reality permanently
hidden from direct experience (i.e., the
very small, the very far away, the very
long ago).
However, Kant’s philosophy expressly
does not permit science somehow
“discovering” that
 space and time are not absolute, or
that
 the real world has more than 3
spatial dimensions, or that
 deterministic causation is not real.
These are a priori truths, the very
conditions of the possibility of scientific
inquiry.
Now, since these are precisely the sorts
of things that what we understand
scientists to have discovered the
Kantian could respond in a few different
ways.
 reject modern science (really bad
idea)
 allow that a priori intuitions are not a
priori, but revisable on empirical
grounds (bummer for the whole
Kantian system)
 allow that science actually can
discover the nature of the noumenon
(which is absurd given the way the
noumenon is described)
Before proceeding let’s be sure we are
clear on some basic stuff that Maddy
does not address in this article.
Prior to Kant, David Hume had codified
a very basic challenge to anyone who
thought it was possible to have a priori
knowledge of the world.
Hume distinguished two ways in which a
statement could be true. One way was
for the statement to represent
contingent matters of fact, the other was
to express necessary relations of ideas.
Kant distinguished these as synthetic
and analytic truths respectively.
Synthetic truths tell us the way the world
is.
 Pluto orbits the sun.
 Rabbits have big ears.
 There are large pyramids in Egypt.
Analytic truths tell us how idea or
concepts are related.
 A planet is a celestial body that: (a)
is in orbit around the Sun, (b) has
sufficient mass for its self-gravity to
overcome rigid body forces so that it
assumes a hydrostatic equilibrium
(nearly round) shape, and (c) has
cleared the neighborhood around its
orbit.
 The ear is a sense organ for hearing.
 A tetrahedron is a pyramid.
Hume’s view gave us the following way
of looking at the relation between
epistemology and metaphysics.
Known A Known A
Priori
Posteriori
Analytic
Truth
Synthetic
Truth
X Ø
K X
Hume’s position serves a radical form of
empiricism, but preserves the idea that
at least some things are knowable a
priori. For Hume, this would include all
of logic and mathematics. But because
logic and mathematics are not synthetic,
it remains mysterious on Hume’s view
why logic and mathematics actually
seem to be useful in grasping the nature
of the external world.
Kant’s response was to claim that Hume
overlooked another class of truths: the
synthetic a priori. These are statements
that are about the world, but knowable a
priori.
But Kant’s real contribution was to show
how this could make sense to someone
with strong empiricist sensibilities. If
mathematical, geometrical, spatial and
logical relationships are understood to
be the forms of human experience
understanding, then we can see
statements representing these
relationships as both knowable a priori
and descriptive of the very structure of
the empirical world.
(Here is a good summary of the above.)
The problem, however, is that these socalled necessary forms of intuition and
understanding turn out not to be
necessary at all. In modern science the
concepts of time, geometry
Carnap’s Linguistic Framework
Carnap was one of the pioneers of the
linguistic turn. For him, philosophy
could only be done with a rigorous grasp
of what a language is and how it works.
One of the most important distinctions to
grasp in this context is the difference
between the “object” or what Carnap
called the “thing” language, and the
meta language.
 The object language is what we use
to talk about the world.
o Object language statement:
There is a pig on the porch.
 The meta language is what we use
to talk about language, specifically
the object language.
o Meta language statement:
“There is a pig on the porch” is
true.
The meta language is what we use to
specify the rules by which the object
language works. It specifies:
 The symbols of the language.
 How the symbols are put together to
form meaningful sentences.
 The basic axioms of the language.
 The rules of evidence for the
language.
So, for example, the meta language will
specify what counts as evidence for the
sentence “There is a pig on the porch”
by specifying the experiences and
relations that count as evidence for and
against that statement.
Carnap distinguished internal questions
from external questions.
Internal questions arise from within the
thing language and are dealt with using
the rules that it employs. An external
question is a question about the
language itself.
 Internal question: Is there a pig on
the porch?
This is a perfectly well formed question
which can be answered using the
specified rules of evidence. However,
 Is there an external physical reality?
is what Carnap would call a pseudo
question. It gets taken seriously
because it has the grammatical form of
an internal question. However, it is not
an internal question that can be
answered using the ordinary rules, but
rather a confused question about the
system itself. For Carnap, questions
about reality arise only internal to the
system. The rules of the language do
not apply to questions about the system
itself.
We can ask meaningful questions about
the system, but these are either going to
be questions about
 how the system works; or
 whether we want to actually use the
system.
But this latter question can not be
meaningfully answered by claiming that
it represents reality better than other
systems. Rather, one can only appeal
to pragmatic criteria: effectiveness,
simplicity, fruitfulness, etc..
Carnap’s a priori/ a posteriori distinction
The concept of the a priori arises in
Carnap’s system by reference to the
linguistic rules.
 A statement will be a posteriori if the
rules for confirming it specify that
certain experiential states must be
instantiated.
 A statement will be a priori if it can
be confirmed simply by applying
rules.
To determine whether there are five pigs
on the porch you will need to have 5
piggy porch experiences. However, to
determine whether 5 is greater than 4,
you need only apply the linguistic rules
governing basic arithmetic.
Comparison between Kant and Carnap
(p. 104-105 Maddy)
Kant distinguished between the
empirical and the transcendental
perspective.
Carnap distinguished between the
internal and the external perspective.
For both Kant and Carnap, in order to
understand how to answer a question
we must be clear about the perspective
from which it is asked. If we do not do
this, then we end up posing pseudo
questions and talking philosophical
nonsense.
For Kant (from the empirical
perspective), and Carnap (from the
internal perspective) the existence of
space, time, physical objects, etc. is a
priori. To question the reality of such
things from within these perspectives is
to pose a pseudo question.
For Kant, these questions are always
implicitly about the a priori forms of
intuition. For Carnap these questions
are always implicitly about the rules for
the linguistic framework being used.
The important dissimilarity is that
Carnap does not think that we are
necessarily constrained to the use of
one language in the way that Kant
thinks we are necessarily constrained to
certain a priori forms of intuition.
Furthermore, Kant and Carnap had the
same problem with the transcendental
perspective.
Kant claimed that transcendental
questions were ultimately
unanswerable, because we could know
nothing at all about the noumenon. But
Kant in fact did try to say things about
the noumenon.
Carnap claimed that external questions
were ultimately pragmatic questions
about the value of a particular linguistic
framework. But it isn’t clear what sort of
linguistic framework we would use to
pose and answer such questions. Is it a
non conventional meta linguistic
framework? If so, we need an account
of it. If not, how would we evaluate the
different answers given by different
alternative meta-languages.
The point here is that in both Kant and
Carnap the viability of the higher
perspective is dubious.
Quine’s critique of Carnap (p. 105-106)
Quine asserted very simply that the
criteria we use for evaluating scientific
hypotheses from within a particular
linguistic framework are not different in
kind from the criteria we use to
determine whether we should expand or
modify a particular linguistic framework.
In other words: if we are operating within
a particular scientific framework, with a
particular ontology and rules of evidence
specified, the value of a new hypothesis
is determined by considerations of
“simplicity, familiarity of principle, scope,
fecundity, and consistency with
experiment.”
If, on the other hand, we are adopting
an external perspective, and trying to
determine whether we should modify the
existing linguistic framework in some
way (e.g., the basic ontology, or the
rules of evidence) we would make
exactly the same sorts of
considerations.
In other words, Carnap’s distinction
between the internal and external
perspectives does not correspond to a
type difference in respect to the relevant
considerations, though there may be a
different emphasis. (E.g., consistency
with experiment may figure more
prominently in internal questions
whereas conceptual simplicity may
figure more prominently in external
questions.)
Neurath’s Boat
The naturalist, then, rejects Carnap’s
distinction between internal and external
questions for the same reason that she
rejects Kant’s distinction between the
empirical and the transcendental:
There is no distinct
transcendental/external perspective to
occupy.
Quine:
“It is within science itself, and not some
prior philosophy, that reality is to be
identified and described.”
“Naturalism does not repudiate
epistemology, but assimilates it to
empirical psychology. Science itself
tells us that our information about the
world is limited to irritations of our
surfaces, and then the epistemological
question is in turn a question within
science: the question how we human
animals can have managed to arrive at
science from such limited information.”
“Neurath has likened science to a boat
which, if we are to rebuild it, we must
rebuild plank by plank while staying
afloat in it.
“The naturalist philosopher begins his
reasoning within the inherited world
theory as a going concern. He
tentatively believes all of it, but believes
also that some unidentified portions are
wrong. He tries to improve, clarify, and
understand the system from within. He
is the busy sailor adrift on Neurath’s
boat.”
Challenges to Quinean Naturalism
Question: Even if Quine is correct that
there is no vantage point outside of
science upon which to base a split-level
conception of inquiry, it does not follow
that science itself does not employ such
a distinction internally.
Maddy thinks science does in fact
employ an important distinction between
theories that are accepted as describing
reality and those that are accepted on a
conventional or pragmatic basis.
Recall that from the Kantian point of
view it makes no sense to ask whether
space time really is 3-dimensional.
Posed from the empirical point of view
this is a category mistake, since 3dimensional space just is the form in
which the empirical point of view is
given. We’ve seen that the Kantian
point of view is mistaken in this regard,
since a multi-dimensional space is not
only perfectly coherent, but scientifically
useful as well.
So it does make sense to ask whether
space, time, causation, etc. are
empirical realities or just useful fictions
after all. Moreover, Maddy points out
that working scientists do distinguish
between the pragmatic value of a theory
and its empirical reality. Atomic theory
is the most recent example of this. In
the early 20th century the theory of the
atom was accepted as highly predictive
and useful, but scientists did not begin
to accept that it was an accurate
representation of reality until long after
all pragmatic tests had been passed.
Interestingly, some theories do not even
seem to be candidates for realistic
interpretation no matter how useful they
are. One current example of the above
is the mathematical assumption that
space-time is continuous, and that it can
be modeled on the real numbers using
the differential equations of the calculus.
This assumption has been hugely
productive. Scientists, however,
continue to regard it as both a sensible
and a completely open question whether
space-time is really continuous. (Kant,
of course, would have regarded it as
neither.)
Despite the fact that the
empirical/pragmatic distinction is useful
within science itself, Maddy concludes
that it does not offer us an alternative
conception of a priori knowledge. There
is, in other words, no internally
recognizable a priori criterion that must
be met in order for a theory to count as
empirical knowledge rather than just
instrumentally useful.
Maddy concludes that questions like
these are inherently questions about the
actual practice of science and can only
be answered by inquiring into the
psychological and social conditions the
incline scientists to interpret the
epistemic/pragmatic value of a theory in
one way or another.