Problems for Verificationism

Problems for Verificationism

RECAP

Verificationism

1. A word or a sentence is conventionally associated with a set of experiences.

2. Those experiences correlate with certain states of the world: whenever you have those experiences, the world is that way.

3. The meaning of a sentence is the set of experiences that verify it.

Mind Experience of a wound

Dagger

Perfectly correlates with

Experiences

“Dagger”

Means

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.

However, as we will see today, the verificationists are largely thought to have eliminated too much.

Too Little is Meaningless

First, one argument that they eliminated too little!

The logical empiricists wanted to say that sentences like “The Absolute is Perfect” and “God exists” are meaningless.

Too Little Is 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:

1. Statements about the past or future.2. Negative existentials.3. Positive universals.4. Certain positivist doctrines.

STATEMENTS ABOUT THE PAST OR FUTURE

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 them.

Statements about the Past

“T. Rex had a blue tongue”

Statements about the Future

“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.

A Confusion

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 “the Absolute is Perfect”– here, no experience will verify that claim, not even possible experience.

Statements about the Future

However, this response only goes so far. What sort of evidence now could conclusively show that hats will be popular on Alpha Centauri?

Reformulation

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.

Russell’s Objection

Bertrand Russell pointed out however that some statements that seem meaningful are not verifiable in principle.

Bertrand Russell

• 3rd Earl Russell, a British nobleman

• Won the Nobel Prize in Literature

• Campaigned against war, and even went to jail

• Greatly influenced the positivists, but was not a positivist

Russell’s Objection

“Neptune existed before it was discovered.”

Russell’s Objection

“Atomic war will kill everyone.”

THE VERIFIABILITY CRITERION ITSELF

The Verifiability Criterion Itself

Consider the verifiability criterion: “a sentence is meaningless unless some finite procedure can conclusively verify its truth.”

The Verifiability Criterion Itself

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?

Ludwig Wittgenstein

• One of the richest people in Europe at the time

• Gave away his entire fortune

• 3 of his brothers committed suicide

• Fought in both World Wars and hid that he was one of the most famous philosophers in the world

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…”

Kicking Away the Ladder

“He must, so to speak, throw away the ladder after he has climbed up it.”

(Wittgenstein, Tractatus Logico-Philosophicus, 6.54)

EXISTENTIAL AND UNIVERSAL CLAIMS

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.

A Typology of Claims

Type Example

Positive Existential There is an F that is GNegative Existential There is no F that is GPositive Universal Every F is GNegative Universal Not every F is G

A Typology of Claims

Type Example

Positive Existential ∃x (Fx & Gx)Negative Existential ~ x (Fx & Gx)∃Positive Universal ∀x (Fx → Gx)Negative Universal ~ x (Fx → Gx)∀

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.

Example: “The House is on Fire”

Verification Conditions

Example: “The House is on Fire”Falsification Conditions

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.

Neither Verifiable Nor Falsifiable

Furthermore, no set of observations will falsify “For every substance, there exists a solvent,” 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”).

Confirmation

The confirmation conditions of a sentence are the set of experiences that, if we had them, would increase the probability that the sentence is true.

Unlike verification conditions, confirmation conditions don’t guarantee the truth of the sentence, they just make it more likely.

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.

The Basic Idea

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.”

W.V.O. Quine, 1908-2000

• Highly influential 20th Century philosopher at Harvard

• Thought that philosophy and science were all part of the same enterprise

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).

The Second Dogma

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 Quine-Duhem Thesis

“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.

The Quine-Duhem Thesis

Quine is claiming that this does not by itself confirm the statement “There are brick houses on Elm Street.”

The Quine-Duhem Thesis

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).

Underdetermination of Theory by Data

My experiences as of brick houses are compatible with infinitely many theories (actual brick houses, hallucination, computer simulation, visual error…).

Underdetermination of Theory by Data

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.

Ubiquity of Underdetermination

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.

Old Problem

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.

Old Problem

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.

The Web of Belief

Some statements are more toward the “periphery” of the web (observation statements), and they are more likely to change with changing experience.

The Web of Belief

But sometimes “recalcitrant” experience causes us not to revise the periphery, but the more central, deeply theoretical (and even logical) statements.

Beliefs about logic and mathematics

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 theory-dependent, 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.