Verificationism
Classical Empiricism
Last time we learned about the idea theory.
Although it wasn’t confined to the empiricists,
most of them ascribed to it (Locke, Berkeley, and
Hume being the most notable).
Empiricism was variously the doctrine that all
ideas “came from” experience, or that all
knowledge did, or both. (Usually both.)
Classical Empricism
Empiricism had its problems, in addition to
those that the idea theory suffered from:
Experience tells you what is, not what must be/
should be/ will be. Yet we can know some of
these things.
Poverty of the stimulus: We figure out things like
language use faster than experience is capable
of teaching us. This suggests innateness.
Positivism
The French philosopher/ first Western
sociologist Isidore Auguste Marie François Xavier
Comte (1798-1857) theorized that society
progressed in three stages: from the theological,
to the metaphysical, to the “positive.”
Positivism
In the theological stage, people believe any silly
or magical thing their ancestors attributed to
the gods. Next, in the metaphysical stage gods
go out of the picture, but are replaced with
unjustified “metaphysical” assumptions (e.g.
universal human rights). Finally, in the positive
stage, the truth of our beliefs is “positively”
determined. Compte thought science was the
only source of positive determination.
Logical Empiricism/ Positivism
Around the 1920’s in Vienna and Berlin certain
philosophical doctrines became popular, and
their adherents were variously known as Logical
Empiricists or Logical Positivists (sometimes neoPositivists). Notable names included Rudolf
Carnap, Hans Reichenbach, and A.J. Ayer.
Empiricist Criterion of Cognitive
Significance
According to the logical positivists, in order for a
sentence to have cognitive significance (to be
meaningful), it had to have verification
conditions.
(‘Verification’ is a Latinate English word < ‘veri-’
true + ‘facere’ to make. Verification conditions
are conditions under which the truth of a
statement can be conclusively established.)
Empiricist Criterion of Cognitive
Significance
In fact, the positivists maintained that the
meaning of a sentence was its verification
conditions. So a sentence with no verification
conditions– where no experience can establish
its truth– is meaningless.
Truth vs. Verification
Many philosophers (even today) have identified
the meaning of a sentence with its truth
conditions. These are the circumstances in
which the sentence would be true. But the
positivists went farther– they held that the
meaning of a sentence was its verification
conditions– the circumstances in which we
would know the sentence was true.
The Elimination of Metaphysics
This was part of a radical philosophical agenda,
which included “the elimination of
metaphysics.” The idea was to view many
philosophical problems of the past (and also
many religious claims) as meaningless disputes
that could simply be ignored.
The Elimination of Metaphysics
Example: In a religion where God is beyond
human experience, the positivists would say
that “God exists” is neither true nor false but
meaningless, since no experience could verify it.
Kant, Hegel, and Heidegger were also big targets
for the positivists. Example Hegel quote: “But
the other side of its Becoming, History, is a
conscious, self-meditating process — Spirit
emptied out into Time.”
The Elimination of Metaphysics
The positivists even wanted to eliminate a lot of
more down-to-Earth metaphysics:
Modality: We can only experience what is, not
what could possibly be. So statements about
what is (merely) possible are meaningless.
Normativity: We can only experience what is,
not what should morally be. So statements
about what is good or bad are meaningless.
The New Science
There was also a scientific impetus to logical
positivism (beyond the just pro-science message
of positivism). Kant influentially held that
Euclidean geometry was synthetic a priori, and
that our experience must be as of a Euclidean
spacetime. But the Minkowski spacetime in
relativity is non-Euclidean.
Einstein
How do you respond to opponents (classical
physics) that think their theory is knowable in
advance of any argument or evidence? Einstein
responded by operationalizing: imagining rigid
rods extending in all directions, and clocks at
various points. That is, his arguments were
couched in terms of what you could measure or
experience (rather than straightforwardly in
terms of what was true).
Quantum Mechanics
Quantum mechanics also had metaphysical
problems of its own. Several counterintuitive
experiments seemed to suggest that the basic
laws of the universe were not quite consistent
with the laws of logic (e.g. the distribution laws).
This led some physicists to simply deny that
there were questions to be answered beyond
“what do we observe/ experience?”– no
questions like “what is the reality causing the
appearances?”
Empiricist Semantics
According to the positivists, the elimination of
metaphysics followed from the correct account
of meaning. When we understood that meaning
= verification conditions, then we would see that
‘the Absolute is perfect’ or ‘God exists’ can’t
possibly have meanings. Then we would be free
to look into more promising, resolvable
philosophical questions.
Protocol Sentences
We single out a certain, small set of sentences to
be the “protocol” or “observation” sentences.
These sentences are all very simple syntactically,
along the lines of: ‘that is red.’
The importance of the protocol sentences is that
they can be immediately verified. To tell
whether ‘that is red’ is verified (is true), you just
have to look.
Non-Protocol Sentences
All the other meaningful sentences (according to
the verificationist) are defined in terms of the
protocol sentences and the logical vocabulary
(AND, OR, NOT, ALL, SOME, NO, etc.).
For example ‘That is an arthropod’ := That is an
animal AND it has a jointed body AND it has
segmented legs.
Non-Protocol Sentences
Obviously these sorts of definitions work best
with scientific terminology like ‘arthropod,’ but
the positivists were happy with that. It could
turn out that much of our ordinary talk was not
strictly speaking meaningful, but needed to be
regimented in a more scientific language.
Protocol Sentences
There was some measure of debate among the
positivists regarding which sentences actually
qualified as protocol sentences. The simpler the
qualities they are about (e.g. ‘that is red’ ‘that is
warm’ ‘this is joy’) the easier it is to argue that
they can be verified immediately, but the harder
it is to define the rest of the sentences (try
defining “Obama is the president of the US” in
terms of what things are red, warm, joy, etc.!
Protocol Sentences
On the other hand, it’s easier to define more
abstract things if we let sentences like ‘That is a
chair’ or ‘That is a person’ be protocol
sentences. However, can these things really be
immediately verified? Our observations don’t
seem to guarantee that something is a chair (it
might be a fake chair, or the reflection of a chair,
or…)
Carnap’s Aufbau
In the Aufbau (The Logical Structure of the
World), Carnap undertook an ambitious project
to outline how one could translate all “highlevel” talk (e.g. “the train to Vienna is running
late”) into talk about sensations at coordinate
points in the visual field (“quality q is at pointinstant x;y;z;t” [actually it was even more
ambitious]). I should note that Carnap himself
wasn’t much of a fan of the Aufbau after
completing it.
Verificationist Semantics
So here’s the picture: The meaning of a sentence
is the set of experiences that would verify it.
Protocol (observation) sentences are directly
connected with their verification conditions: we
can immediately tell whether they are verified in
any particular circumstance.
Non-protocol sentences inherit their verification
conditions from the protocol sentences they are
logically constructed out of.
Special Exception
One exception was made: logic and
mathematics were held to be meaningful, even
though its hard to state (for example) what
experiences would confirm “2 + 2 = 4.”
Intuitionism (constructivism) was a positivistinfluenced, non-classical approach to logic and
mathematics that said that only provable
formulas (only “mathematically verifiable”
formulas) were true (denial of excluded middle).
COMPARISON WITH THE IDEA
THEORY
The Idea Theory
Here were the essential parts of the idea theory:
1. Words and sentences are the visible,
conventional signs of ideas.
2. Ideas represent things in the world by
resembling (non-conventional) them.
3. We can treat the meaning of a word as either
the idea it is a sign of, or the thing that idea
represents (it doesn’t really matter).
Verificationism
Verificationism is similar. A word or a sentence
was conventionally associated with a set of
experiences. Those experiences verify (“make
true,” a non-conventional relation) that things in
the world are a certain way because of a perfect
correlation between the experiences and the
states they verify. Sometimes this correlation
was enforced by an idealist worldview, or a view
on which the external world was logically
constructed from sense data.
Representation is Not an Equivalence
Relation
A main problem for the idea theory was its
identification of representation with
resemblance. While resemblance is an
equivalence relation (reflexive, symmetric, and
transitive), representation is not.
Reflexivity
But the verificationist thinks that the meaning of
a sentence is the experience(s) that would verify
it. Thus it follows (correctly) that most sentences
do not represent themselves, because most
sentences don’t verify themselves (exception:
the sentence “This is a sentence”).
Abstract Concepts
Idea theorists, as we saw, also had a problem
with abstract ideas, as no picture equally
resembles a fat man and a skinny man. One
potential line of response we saw was to let
abstract ideas be a collection of ideas, and to say
that the collection represented what is common
(shared by) all the items in the collection.
Abstract Concepts
The verificationist strategy was similar: the
meaning of ‘x is a dog’ was the collection of
experiences that would verify it. However, these
experiences need not share any features: one
might be an experience I’d have with my eyes
closed (shaggy coat feeling, barking noises), and
another might involve visual impressions of a
dog. Both could verify ‘x is a dog.’
Only So Much Time…
Obviously, I can’t re-cover every objection we
considered to the idea theory and then see how
the verificationist does with respect to that
question.
BUT, that doesn’t mean that wouldn’t be an
interesting paper topic for you to do.
Theoretical Concepts
One last issue though. Verificationism was
thought to have particular trouble with
theoretical concepts (that is, with representing
theoretical entities) like electrons or DNA.
(These are called “theoretical entities” because
we can’t observe them directly, but their
existence is confirmed by their characteristic
effects as described by our scientific theories.
Example: effects of charged particles in cloud
chambers.)
Idea Theory vs. Theoretical Entities
The idea theory had it pretty bad with respect to
such entities, but no one who lived at the time
the idea theory was big knew this. For all
anybody knew, particles were very much like
mental pictures of little tiny pool balls. But now
its implausible to think that anyone’s “mental
images” of an electron come close to resembling
electrons.
Verificationism vs. Theoretical Entities
Verificationism was fine here, at least insofar as
you could say that the behavior of the gas in the
cloud chamber verified the existence of
electrons, even though it didn’t resemble them.
The Problem
The problem was that the meanings of scientific
terms was supposed to be fixed in advance. Yet
for many theoretical terms, it took years or
decades after their introduction for us to
discover any way of verifying claims about them.
(Compare: ‘x is a Higgs Boson.’) So did claims
about electrons, positrons, mesons, or whatever
not mean anything until we discovered ways of
verifying them. And did we discover their
meanings then?
PROBLEMS FOR VERIFICATIONISM
Too Little is Meaningless
The logical empiricists wanted to say that
sentences like “The Absolute is Perfect” and
“God exists” are meaningless. If you’re of that
persuasion, you’re likely to think that “Either
some socks are cotton or the Absolute is
Perfect” and “Either God exists or snow is
purple” are also meaningless. But the latter two
clearly have conditions that would verify them.
Too Much Is Meaningless
A bigger focus of criticism, however, was that
according too the verifiability criterion, too
much is meaningless, including:
•
•
•
•
Statements about the past or future.
Negative existentials.
Positive universals.
Certain positivist doctrines.
Statements about the Past/ Future
One objection to the verifiability criterion was
that it made statements about the distant past
or the distant future meaningless, since there is
no way of verifying, for example, the statement
“T. Rex had a blue tongue” or “Hats will be
popular among the first humans that colonize
Alpha Centauri.”
A Confusion
This objection is a little bit confused. Positivists
don’t claim that for any meaningful sentence,
there actually exists evidence you could find
that would (when you found it) confirm that
sentence. This would imply that every
meaningful sentence was true. To be
meaningful, a sentence just has to have
verification conditions– it has to be possible for
there to be circumstances that verify it.
A Confusion
So I could, possibly, verify that T. Rex had a blue
tongue by finding a perfectly preserved frozen T.
Rex with a blue tongue.
Sure, that won’t happen, but that’s not the
point. Compare “God exists”– here, no
experience will verify that claim, not even
possible experience.
Reformulation
However, this response only goes so far. What
sort of evidence now could conclusively show
that hats will be popular on Alpha Centauri?
Additionally, we can reformulate the objection.
Events outside my light-cone cannot affect me.
So in what sense is it even possible to verify “A
dinosaur outside my light-cone has a blue
tongue”?
Verifiability “In Principle”
However, the objection isn’t so simple: complex
sentences like this were supposed to be built
out of protocol sentences like ‘x is a T. Rex’ and
‘x is blue’ and ‘x is a tongue.’ Each of these has
verification conditions. So we can say that a
sentence is verifiable in principle if it is a logical
construct out of protocol sentences, each of
which is verifiable in the old sense.
Verifiability “In Principle”
Russell pointed out however that some
statements that seem meaningful are not
verifiable in principle:
• Neptune existed before it was discovered.
• Atomic war will kill everyone.
Someone couldn’t verify (1) before the discovery
of Neptune, and they couldn’t verify it afterward
either! Similar remarks go for (2).
The Verifiability Criterion Itself
Consider the verifiability criterion: “a sentence is
meaningless unless some finite procedure can
conclusively verify its truth.” If this criterion is
meaningful, then it must be that some finite
procedure can conclusively verify the claim that
a sentence is meaningless unless some finite
procedure can conclusively verify its truth. But
what procedure would that be? (Also note that
the criterion doesn’t meet the special exception,
because it’s not a logical truth either.)
Kicking Away the Ladder
“My propositions serve as elucidations in the
following way: anyone who understands me
eventually recognizes them as nonsensical,
when he has used them - as steps - to climb
beyond them. He must, so to speak, throw away
the ladder after he has climbed up it.”
(Wittgenstein, Tractatus Logico-Philosophicus,
6.54)
Existentials and Universals
Here’s a(n incomplete) typology of claims:
Positive existential: There is an F that is G.
Negative existential: There is no F that is G.
Positive universal: Every F is G.
Negative universal: Not every F is G.
Existentials and Universals
Positive existential claims and negative universal
claims can be verified by a finite number of
experiences. For instance, it suffices to observe
just one cow that is dangerous to know that:
• There is a cow that is dangerous.
• Not every cow is safe.
Existentials and Universals
However, negative existentials and positive
universals cannot be verified by a finite number
of claims. If I observe one billion cows that are
dangerous, I still have not shown conclusively:
• There is no cow that is safe.
• All cows are dangerous.
Negative Existentials
Russell tells the following story: “[Wittgenstein]
maintained, for example, at one time that all
existential propositions are meaningless. This
was in a lecture room, and I invited him to
consider the proposition: 'There is no
hippopotamus in this room at present.' When he
refused to believe this, I looked under all the
desks without finding one; but he remained
unconvinced.”
Falsificationism
We might choose to instead identify the
meaning of a sentence with its falsification
conditions (rather than its verification
conditions). These are the circumstances under
which it can conclusively be known to be false.
Falsificationism
This resolves the negative existentials and and
positive universals. Observing one safe cow is
enough to falsify:
• There is no cow that is safe.
• All cows are dangerous.
Falsificationism
However, this just turns the tables: now we can’t
handle positive existentials or negative
universals: even observing one billion cows that
are safe, I still have not falsified with certainty:
• There is a cow that is dangerous.
• Not all cows are safe.
Falsificationism too Loose
Additionally, since both “The absolute is perfect
and some socks are made of cotton” and “Snow
is purple and God exists” are falsifiable, they
turn out perfectly meaningful for the
falsificationist.
It seems as though falsificationism is no better
off than verificationism.
Would it help to say:
New Criterion: A sentence S is only meaningful if
one or more of the following is true:
• S is a logical truth.
• S is verifiable.
• S is falsifiable.
All over Some
Surprisingly, that would not help. Consider the
sentence, “For any substance, there exists a
solvent,” and consider some set of observations:
•
•
•
•
A dissolves X
B dissolves X
C dissolves Y
C dissolves Z
Neither Verifiable Nor Falsifiable
No matter how many observations you pile up,
the sentence “For any substance, there exists a
solvent” will not be verified conclusively.
Because there may always be a substance you
have not yet considered that does not have a
solvent. Furthermore, no set of observations will
falsify the sentence, because even if you have
yet to find a solvent for substance S, there may
always be one you have not yet considered.
CONFIRMATIONISM
Confirmationism
One move to lessen some of the negative
implications of verificationism was to deny that
the meaning of a sentence was the conditions
under which it was verified (or falsified), and
instead identify it with the conditions under
which the statement was confirmed (or
“infirmed”).
The Basic Idea
So even if nothing conclusively guaranteed the
truth or falsity of “for every substance, there
exists a solvent,” the fact that you’d found a
billion substances, and a solvent for each one,
strongly confirmed that hypothesis. Or the fact
that you searched for a billion years extensively,
and have yet to find solvents for over a billion
substances strongly disconfirmed (“infirmed”) it.
Nice Try
This was a nice suggestion, but ultimately it
failed too, and American philosopher W.V.O.
Quine is widely recognized to have put the nail
in the coffin of verificationism/ confirmationism
in his landmark essay “Two Dogmas of
Empiricism.”
Two Dogmas
By the time Quine wrote “Two Dogmas of
Empiricism” in 1951, logical positivism was
pretty unpopular. Still, “Two Dogmas” was
insanely influential, and is easily one of the most
important works of 20th Century “analytic”
philosophy.
Analytic/ Synthetic Distinction
Quine’s first attack is on the dogma (of
empiricism) that there’s a distinction between
analytic and synthetic truths– things that are
true because of what they mean (“vixens are
female foxes”) and things that are true because
of the facts (“there are vixens in our back yard”).
Non-Central
As we’ve seen, the positivists assumed such a
distinction, but there’s no reason to think that
it’s central to verificationism/ confirmationism.
In fact, I’ve characterized the positivist
treatment of logical and mathematical truths as
a “special exception”– they wouldn’t need a
special exception if they admitted, with Quine,
that nothing is wholly analytic.
The Second Dogma
The good stuff starts in Section 5, “The
Verification Theory and Reductionism.” Here,
the dogma at issue is verificationism (how we’ve
been using the terminology: confirmationism).
Quine also calls it ‘radical reductionism’ because
it maintains that every sentence ultimately has a
meaning that is just a set of personal
experiences. It “reduces” statements about
chairs and tables, to statements about personal
experiences.
The Quine-Duhem Thesis
“[It’s not true] that each statement, taken in
isolation of its fellows can admit of confirmation
or infirmation… Our statements about the
external world face the tribunal of sense
experience not individually but as a corporate
body.” (“Two Dogmas,” p. 41).
“The unit of empirical significance is the whole
of science.” (“Two Dogmas,” p. 42).
The Quine-Duhem Thesis
Here’s the general picture. Suppose I have an
experience as of seeing brick houses on Elm
Street. Quine is claiming that this does not by
itself confirm the statement “There are brick
houses on Elm Street.” If I had strong prior
beliefs that, for instance, all bricks had been
destroyed and that I’d been given a powerful
hallicinogen that made me see brick houses,
then I would not assign a higher probability to
this claim.
Underdetermination of Theory by Data
Our observational data (experiences)
underdetermine our theories (claims about the
extra-mental world). My experiences as of brick
houses are compatible with infinitely many
theories (actual brick houses, hallucination,
computer simulation, visual error…). Only my
entire body of beliefs (that I’m not hallucinating,
that my eyes are working properly, that I seem
to be seeing brick houses) confirms or
disconfirms a theoretical statement.
Ubiquity of Underdetermination
This is not just reserved for “skeptical”
scenarios. Lots of evidence seems to confirm the
thesis that the Earth does not move: we aren’t,
for instance, thrown off of it as it hurtles
through space. The individuals in the past who
took this as evidence for a stationary Earth had a
mistaken theory of motion. Against the
background of modern theory, this is not
confirmatory evidence at all.
Old Problem
This is actually the same problem as we
considered before: verificationism vs. theoretical
statements. The reason we discover methods of
verification, rather than stipulate them in
advance, is that our theories advance, and
according to the new theories, certain
experiences confirm certain phenomena. If our
theories change, those same experiences may
no longer confirm those same phenomena.
The Web of Belief
Quine’s picture is that our beliefs form a “web”
where change in the degree of belief in any
statement affects the degrees of belief in all of the
others, simultaneously. Some statements are more
toward the “periphery” of the web (observation
statements), and they are more likely to change
with changing experience. But sometimes
“recalcitrant” experience causes us not to revise the
periphery, but the more central, deeply theoretical
(and even logical) statements.
SUMMARY
Verificationism
Verificationism is the view that the meaning of a
statement is the conditions under which it is
verified– the experiences such that if you have
them, then the statement is true.
Aims and Influence
The project was influential: both influenced by
and influencing the science of the time. It
advocated the radical elimination of all
metaphysics and normativity (art, morality) in
favor of a regimented, operationalist science.
Early Problems
Early problems for verificationism included:
• It couldn’t make sense of the discovery of
methods of verification for theoretical
entities.
• It seemed incompatible with meaningful
statements about things not possible to
experience.
• It threw out various clearly scientifically
acceptable claims “For every substance…”
Confirmationism
Many positivists thought that the limitations of
verificationism could be overcome by
generalizing the idea to confirmationism: the
meaning of a statement is the conditions under
which it is confirmed– the experiences such
that, if you have them, the statement is more
likely to be true.
The Quine-Duhem Thesis
However, philosophers of science eventually
came to accept that confirmation is theorydependent, meaning that it made no sense to
ask what experiences confirm or disconfirm
statement X– only what experiences confirm or
disconfirm X relative to theory T.
Holism
It was thus possible to continue to maintain
confirmationism, at the cost of holism. If
confirmation is theory-dependent, and meaning
= confirmation conditions, then meaning is
theory dependent: two people with different
theories cannot mean the same thing by the
same statement. Different philosophers differ in
their taste for such holism.