Verificationism

Logical Positivism

Classical Empiricism

Last time we learned about the idea theory.

Although it wasn’t confined to the empiricists, most of the important ones– Locke, Berkeley, and Hume– believed in it.

Classical Empiricism

“All ideas come from experience.”

“All knowledge comes from experience.”

“All ideas and all knowledge come from experience.”

Classical Empricism

Empiricism had its problems, in addition to those that the idea theory suffered from:

Modal Knowledge: 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: 1. Theological2. Metaphysical3. Positive

Theological Stage

In the theological stage, people believe any silly or magical thing their ancestors attributed to the gods.

Metaphysical Stage

Next, in the metaphysical stage gods go out of the picture, but are replaced with unjustified “metaphysical” assumptions.

Example: universal human rights.

Positivism

Finally, in the positive stage, the truth of our beliefs is “positively” determined.

For Compte, science was the only source of positive determination.

Logical 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 or sometimes neo-Positivists.

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.

Empiricist Criterion of Cognitive Significance

‘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.

Example: “The House is on Fire”

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.

Anti-Religion

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.

Anti-MetaphysicsKant, 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.

Metaphysics! Metaphysics!

The new science: relativity and quantum mechanics

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

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).

The Twins Paradox

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.

Quantum Mechanics

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?”

Verificationist Semantics

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.

Observation 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.’

Immediate ExperienceRED

PAIN

LOUD

THREE

TABLE DOG

MOUNTAIN CHAIR

Observation Sentences

The importance of the observation sentences is that they can be immediately verified.

To tell whether ‘that is red’ is verified (is true), you just have to look.

Non-Observation 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.).

Definition of ‘Arthropod’

Example

‘That is an arthropod’ :=def

That is an animal AND it has a jointed body AND it has segmented legs.

Non-Observation 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.

Observation Sentences

There was some measure of debate among the positivists regarding which sentences actually qualified as observation 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.

Observation Sentences

Try defining “CY Leung is the chief executive of Hong Kong” in terms of what things are red, warm, joy, etc.!

Observation 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 observation sentences.

However, can these things really be immediately verified?

Our observations don’t seem to guarantee that something is a gorilla (it might be a man in a costume, or the reflection of a gorilla, or…)

The Aufbau

In the Aufbau (The Logical Structure of the World), Carnap undertook an ambitious project to outline how one could translate all “high-level” 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 point-instant x;y;z;t”

Verificationist Semantics

So here’s the picture: #1. The meaning of a sentence is the set of experiences that would verify it.#2. Observation sentences are directly connected with their verification conditions: we can immediately tell whether they are verified in any particular circumstance.#3. Non-observation sentences inherit their verification conditions from the observation 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.”

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).

Mind Idea of a Dagger

Dagger

Resembles

Sees

“Dagger”

Represents

Verificationism

Verificationism is similar.

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

2. 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.

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

Mind Idea of a Dagger

Dagger

Verifies

Experiences

“Dagger”

Represents

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.

Abstract Concepts

For the verificationist, the meaning of ‘there is a fire’ was the collection of experiences that would verify it.

However, these experiences need not share any features, and they need not resemble what they represent.

“Fire”

Problem #1 Eliminated Too Little

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

But consider:

• “Either some socks are cotton or the Absolute is Perfect.”• “Either God exists or snow is

purple.”

They 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 theoretical entities.2. Statements about the past or future.3. Negative existentials.4. Positive universals.5. Certain positivist doctrines.

Problem #2 Theoretical Entities

Theoretical Concepts

Verificationism was thought to have particular trouble with theoretical concepts (that is, with representing theoretical entities) like electrons or DNA.

Verificationism vs. Theoretical EntitiesThese 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.

Verificationism vs. Theoretical Entities

The positivist can 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.

The Problem

Consider the claim:

“DNA has a double-helical structure.”

This claim seems to be meaningful.

The Problem

But Watson and Crick had to discover how to verify it.

The Problem

So positivism seems to suggest that claims about DNA, electrons, positrons, Higgs Bosons, or whatever did not mean anything until we discovered ways of verifying them.

At that time we discovered their meanings.

Problem #3 Statements about the Past and the 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 positivist 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 normal sense.

Russell’s Objection

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

Russell’s Objection

“Neptune existed before it was discovered.”

Russell’s Objection

“Atomic war will kill everyone.”

Problem #4The 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)

Problem #5Existential 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

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.”