What Is Science?

The Cognitive Uses of Causal OrderLecture IV

The Demarcation Problem

What makes science different?

Popper’s Question

What makes science different from pseudoscience?

My Question

What makes science different from other forms of inquiry?

Especially respectable forms of inquiry…

Most especially respectable forms of inductive i.e. ampliative or non-deductive inquiry.

Some Forms of Inductive Inquiry

❖ Interpretation of sacred texts

❖ Other hermeneutic pursuits

❖ Systematic metaphysics

❖ Gathering folk wisdom

❖ Science

How Is Science Different?

❖ Better funded

❖ Special social organization

❖ Smarter personnel

❖ More empirical

How Is Science Different?

❖ Better funded

❖ Special social organization

❖ Smarter personnel

❖ More empirical

Empirical Exceptionalism

Science is more empirical than other knowledge-oriented pursuits

And because it is more empirical, it is in some ways better

(And maybe, in some ways, worse)

Exceptionalism in Recent Times

Critique of intelligent design movement

Three Ways To Be “Empirical”

1. Base your conclusions on observable phenomena

2. Test hypotheses with empirical content

3. Focus on a particular kind of relation between evidence and hypothesis: empirical confirmation

Confirmation

A piece of evidence confirms a hypothesis just in case it gives you more reason to believe the hypothesis than before

Used to be called: incremental confirmation

That a hypothesis is “confirmed” does not mean that it is likely to be true

Toward a Demarcation Criterion…

Science: Much deductive reasoning, much learning from authority, but all must be based in a substantial body of knowledge gained from empirical confirmation

Non-Science: Empirical confirmation, where it exists, is peripheral

Empirical Confirmation

Illustrated

Two Respectable Ways of Learning about Ravens

Empiricus:Go into the field, find ravens, observe their color, infer that all ravens are black

Two Respectable Ways of Learning about Ravens

Lector:Go to the library, read up on ornithology, find reputable authorities on raven color, infer that all ravens are black

Similarities

❖ Same hypothesis

❖ Supported inductively

❖ Evidence obtained through observation (raven color; sentences)

❖ A good way to learn

Difference

❖ Empiricus’s data empirically confirms the hypothesis, whereas Lector’s data does not.

Inductive Support and Empirical Confirmation

A fact inductively supports a hypothesis whenever it increases your confidence that the hypothesis is true.

Empirical confirmation is a kind of inductive support, but not the only kind – not even the only good kind – though maybe the best.

Good inductive inference

Empirical inference

Empirical Confirmation Is Essential to Science

There is much inductive support in science that is not empirical confirmation: books, journals, ornithological compendia…

But such things are “scientific” only insofar as the facts they convey are learned ultimately by empirical confirmation

What makes science special is that…

It is founded in a substantial body of empirical testing

Science Demarcated

Two Routes to a Theory of Empirical Confirmation

1. Build a self-standing theory of empirical inference

2. Given a theory of inductive support, specify a criterion for picking out the support relations that are empirical

Two Routes to a Theory of Empirical Confirmation

1. Build a self-standing theory of empirical inference

2. Given a theory of inductive support, specify a criterion for picking out the support relations that are empirical

Good inductive inference

Empirical inference

What Is Empirical Confirmation?

Empirical confirmation is instance confirmation

More Exactly…

Evidence e empirically confirms hypothesis h just in case

1. The evidence inductively supports h

2. The evidence instance-confirms h, either directly or indirectly

Instance Confirmation Repurposed

❖ It is no longer an account of confirmation (that’s the job of the theory of support)

❖ It is an account of which support relations are empirical

Plan

1. A look at Hempel’s account of instance confirmation and its problems

2. A rival “causal” account that captures something intuitively empirical

3. Virtues of this kind of inductive support

Hempel’s Instantialism

Three Parts

1. Setup: the relata of the confirmation relation are sentences (hypothesis and evidence statement)

2. Direct confirmation

3. Indirect confirmation

Direct Confirmation

A hypothesis is confirmed by its positive instances and disconfirmed by its negative instances

(After Jean Nicod)

Instancehood

An evidence statement is a positive instance of All Fs are G just in case it entails that no object mentioned in the statement is a counterexample – an F that is not G.

☛ An F that is G

☛ A non-F

Indirect Confirmation

Consequence Principle: If e directly confirms (i.e., instantiates) one or more hypotheses, it indirectly confirms all logical consequences of those hypotheses.

e

h

kInstantiation

Entailment

Claims

Hempel confirmation is a prima facie a lot like empirical confirmation

What makes science special is the foundational role played by inductive support relations that are cases of instance confirmation

Difficulties with Hempel’s Instantialism

Four Problems

1. Only hypotheses about observables can be directly confirmed

2. Only hypotheses about observables can be indirectly confirmed

3. The white shoe

4. The Good problem

e

h

k

t

InstantiationEntailment

The Good Problem

World 1: 1000 objects, 901 ravens, 900 black

World 2: 1000 objects, 100 ravens, all black

The first thing you see is a black raven. Which world are you more likely to be in?

One Way Out of the Good Problem

Instance confirmation alone is not sufficient for empirical confirmation; you need inductive support as well.

The black raven does not empirically confirm the raven hypothesis

Nor does it empirically disconfirm it

Causal Instantialism

Limited to: Causal Hypotheses

An In conditions Z, all Fs are G style hypothesis putatively true in virtue of a causal mechanism by which, in conditions Z, something about Fs causes G-hood

Target Mechanism

For a causal hypothesis In Z, all Fs are G:

☛ The actual mechanism whose consequences the hypothesis is supposed to describe

Associated Theory

For a causal hypothesis is the prevailing theory of the nature of the target mechanism

It’s what is taken to causally explain the hypothesis, if it’s true

Direct Confirmation

A hypothesis is confirmed by its positive instances and disconfirmed by its negative instances.

Instancehood

A state of affairs is an instance of If Z, all Fs are G just in case it is an F in conditions Z that is produced by the target mechanism

If it’s G, it’s a positive instance, if it’s not G, it’s a negative instance

Positive Instance

An instance that conforms to the hypothesis – a case where the hypothesis makes the correct prediction

A state of affairs is a positive instance of If Z, all Fs are G just in case it is an F in conditions Z that is produced by the target mechanism and that is G.

Instance Confirmation

A hypothesis is confirmed by its positive instances and disconfirmed by its negative instances

Indirect Confirmation

What is indirectly confirmed:

1. Associated theory

2. Hypotheses explained by associated theory

3. Initial conditions needed to explain this particular instance

4. G-hood of other Fs (in conditions Z)

Indirect Confirmation When e Instantiates h

1. The theory t that explains h

2. The other hypotheses explained by t

3. The initial conditions that explain e

4. The other things (instance predictions) explained by h

e

h

t

Initial conditions

Other hypotheses

Other instances

e

h

t

Initial conditions

Other hypotheses

Other instances

How to Get from Observed Premises to

Theoretical Conclusions

Example

Theory: Inflationary big bang cosmology

Hypothesis: The cosmic microwave background has such and such structure

Evidence: Observations of the microwave background

Theoretical Instances

Can All Fs are G be directly confirmed when F and G are theoretical, not observable, properties?

Yes, if you have evidence which confirms the existence of an F that also G – an instance.

Example

All electrons have charge 1.602 × 10–19 C

Instance-confirmed by an electron with such a charge

How to indirectly confirm such a state of affairs: find an effect that it helps to explain

Example

1. Observed motion of oil drop instantiates hypothesis about motion of drops

2. Indirectly confirm initial conditions used in explanation of motion

3. These include presence of electron with such-and-such charge

Four Problems in Hempel

1. Only hypotheses about observables can be directly confirmed

2. No upward flow of indirect confirmation from directly confirmed hypothesis

3. The white shoe

4. The Good problem

What makes science special is that…

It is founded in a substantial body of empirical confirmation

Science Demarcated

The Epistemic Virtues of Empirical Confirmation

Reasons to Use the Library

1. Fast

2. Efficient

3. Inexpensive

4. Reliable

Reasons to Go Empirical?

Empirical confirmation is not dependent on background beliefs

Or at least, not so much as other forms of inductive reasoning

Dangers of Non-Empirical Reasoning

Metaphysical background beliefs:

Empiricus: What Aristotle says is typically true

Lector: What Aristotle says is almost always false

It Can’t Happen with Direct Confirmation

Facts about instancehood are totally determined by form of hypothesis and nature of target mechanism

It Can Happen with Indirect Confirmation

Look at confirmation of associated theories

Two theories: one posits p, other posits ¬p

As All Fs are G gets confirmed, opinions as to p or ¬p diverge

But…

If the theories, or p itself, are causal hypotheses…

☛ Use empirical testing to distinguish which of p and ¬p is true, or

☛ Use empirical testing to distinguish which of the two theories of the F/G connection is true

Concluding Unscientific Postscript

Two Complaints

1. Empirical reasoning – reasoning from effect to cause – ignores too much information of inductive importance

2. Empirical reasoning makes too many assumptions about the world’s causal structure

First Complaint

Important information ignored?

๏ That is the secret of science’s independence of background knowledge

๏ Tradeoff: Ignore relevant information for (perhaps) a longer-term gain

Second Complaint

Have we built too many worldly assumptions into scientific reasoning?

Reason, in order to be taught by nature, must approach nature with its

principles in one handKant, Critique of Pure Reason

Michael StrevensPhilosophy DepartmentNew York Universitywww.strevens.orgstrevens@nyu.edu