Why Think Causally

8/13/2019 Why Think Causally

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Why Care AboutCounterfactual

Support?The Cognitive Uses of Causal Order

Lecture 2


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You Do Care About

Counterfactual

Su ort


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Two Regularities

All uranium spheres are less than a mile in

diameterAll gold spheres are less than a mile indiameter


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Two Regularities

All uranium spheres are less than a mile in

diameterAll gold spheres are less than a mile indiameter


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Two More Regularities

All ravens are black

All members of the 1964 GreenburySchool Board are bald


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Two More Regularities

All ravens are black

All members of the 1964 GreenburySchool Board are bald


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Conclusion

Some true generalizations are law-like;

some are notBut what is lawlikeness?


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Answer

A lawlike generalization supports

counterfactuals


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Two Counterfactuals

If these two ravens were to mate, their

offspring would be blackIf Hilary Clinton were elected to the 1964Greenbury School Board, her hair would

fall out


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Counterfactuals andLawlikeness

The baldness of the school board members

is a coincidence; if things had gonedifferently, baldness would not be universal

The blackness of ravens is not a

coincidence; if things had gone (somewhat)differently, blackness would still beuniversal


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Counterfactuals andLawlikeness

The baldness of the school board members

is a coincidence; if things had gonedifferently, baldness would not be universal

The blackness of ravens is not a

coincidence; if things had gone (somewhat)differently, blackness would still beuniversal


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Counterfactual Support

A generalizationAll Fs are Goffers

counterfactual support if1. Actual Fs in non-actual circumstances

would still be G

2. Non-actual Fs would be G

A matter of degree


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You Care AboutCounterfactual Support

If you care about the distinction between

law-like and accidental regularitiesThere are other reasons, too


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The Empiricist CaseAgainst Caring


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The Logical Empiricists

Rudolf Carnap

Hans Reichenbach

Carl Hempel


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The Actual and the Modal

Actual fact: a fact about what happens in

the actual (even observable) worldModal fact: facts about possibilities,necessities, what might but did not happen,

what could not happen


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Two Positivist Theses

Only the actual is knowable

Only the actual has practical significance


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Only the Actual HasPractical Significance

Modal facts cannot make a difference to

our realizing the goals of science


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The Goals of Science

1. Explanation

2. Prediction

3. Control


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The Empiricist Theoryof Explanation

Hempel: To understand a phenomenon is to

be able to predict the phenomenon (atleast in retrospect)

In order to explain, learn how to predict


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The Goals of Science

1. Explanation

2. Prediction

3. Control


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The Actual and the ModalAspects of a Regularity

1. Actual: All actual ravens are actually

black2. (a) In some counterfactual

circumstances, some actual ravens

would be black(b) Some non-actual ravens, if theyexisted, would be black


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Prediction and Control

Are about actual outcomes

Thus they are covered by the actual part ofa regularity

Nothing else matters

In particular, the modal part does notmatter


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The Empiricist Position

We may care about counterfactual

supportbut we should not

Find a new definition of law-likeness


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Against the Empiricists

But Not Against

Empiricism


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My Claims

Paying attention to counterfactual facts can

make a difference to prediction and controlEven given all empiricist assumptions

Because counterfactual facts are at bottom

facts about the actual world importantfacts!


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Explaining Caring aboutCounterfactual Support

I will put one piece of an explanation in

place: explain practical significance ofcaring

What then must be added: evolution?

something else?


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Some AttemptsTo Care


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Two Failed Attempts toExplain Caring

1. Planning explanation

2. Induction explanation


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Planning Explanation


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Planning my actions requires counterfactual

thinking


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When I plan what to do, I select from

several possible actions the one that willbest realize my goal

For each action I ask: what would happen

if I were to do that?I decide by the counterfactual answers


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Empiricist Reply

This may be the way that humans actually

plan, but there is another way to plan thatdoes not require counterfactual thinking


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Empiricist Planning

Look at actual frequencies

Perform the action that most often leads tothe goal (other things being equal)

Claim: this is for practical purposes

identical to counterfactual planning


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Induction Explanation


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Induction Explanation

In order to learn the actual part of a

regularity, I must learn its modal partIf the actual part is the practical end, themodal part is the means to that end


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Inductive Argument

From the fact that

! All observed Fs are G

infer that

!

AllFs are

G


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Thesis

In order to perform this inference, you must

have reason to believe that! All observed Fs are G

is not an accident or a coincidence

So: require counterfactual knowledge


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Problem

The thesis is implausibly strong

A better thesis: in order to make theinference, you should lack reason tobelieve that the G-ness of observed Fs is a

coincidence


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The Theses Contrasted

To inferAll Fs are G, must have reasonto

believe that the G-ness of observed Fs isnot an accident

To inferAll Fs are G, must lack reasonto

believe that the G-ness of observed Fs is anaccident

O h i H C


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Otherwise, How CanInduction Get Started?

We cannot have reason to believe that a

pattern is not an accident until we havedone some inductive inference


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Lets look for something else


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What Is

Counterfactual

Su ort, Reall ?


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How Counterfactuals Work

Robert Stalnaker

David Lewis

Jonathan Bennett


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Closest Possible Worlds?

Sounds like the truth or falsity of the

counterfactual depends on the spatialstructure of some hyper-universe full of non-actual worlds


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World Proximity

1. Same history as actual world

2. Something in recent past goes slightlydifferently, so that pen is dropped

3. Same fundamental laws as actual world

Note that (2) implies partial exceptions to(1) and (3): make these very small


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Very Small

The thing that happens, so that the pen is

dropped, must1. Change as little as possible about past

history

2. Violate the laws as little as possible


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Putting it all together


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E l ti W ld f A


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Evaluation Worlds forA(Lewis, Bennett)

1. Same history as actual world until

shortly before occurrence ofA

2. Then there is a conservative deviationfrom actual history that brings aboutA

3. From then on, actual laws determinewhat occurs

C ti D i ti


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Conservative Deviation(Lewis, Bennett)

1. Happens as close toAas possible

2. Has as few side effects as possible

3. If possible, violates no laws and is nottoo improbable

4. If violation is necessary, it is discreet


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Restrictions

This story is correct for ordinary

counterfactuals


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Closest Possible Worlds?

Sounds like the truth or falsity of the

counterfactual depends on the spatialstructure of some hyper-universe full of non-actual worlds

Wrong


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Closest Possible Worlds

What happens in the closest worlds

depends on:1. Actual history

2. Actual laws

3. Criteria for conservative deviation


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Closest Possible Worlds

What makes counterfactual claims true or

false are facts about the actual worldSpecifically: Ordinary occurrent facts andfacts about laws

Empiricists are OK with both


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Thesis

If the facts that make a counterfactual claim

true are actual facts, then the modalaspect of a regularity is something actual

And so can make a difference even in the

empiricists sense prediction & control


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Question

Still, even if an interest in counterfactuals is

an interest in actual facts, whythese

actualfacts? They look like a rather arbitraryselection


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The Modal Aspectof a Regularity

The Actual and the Modal


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The Actual and the ModalAspects of a Regularity

1. Actual: All actual ravens are actuallyblack

2. (a) In some counterfactualcircumstances, some actual ravens

would be black(b) Some non-actual ravens, if theyexisted, would be black


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All Ravens Are Black

! If these two ravens had mated, theiroffspring would have been black

! If this raven had been fed a diet ofworms, it would still have been black


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Some Raven Physiology

Tyrosinase helps to covert tyrosine tomelanin inside the melanosomes

Melanosomes are incorporated intofeather-producing cells

Much physical structure: bundle it togetherand call it P


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All Ravens Have P

That is, they all have this complicatedphysical structure that makes them black

Include in Pthe physical structure thatensures that Pis passed from parents to

offspring


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A Raven Counterfactual

If these two ravens had mated, theiroffspring would have been black

Find the closest worlds where the ravensmate


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Closest Mating Worlds

1. Same history as actual world untilshortly before mating

2. Conservative deviation brings aboutmating

3. From then on, actual laws apply


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Closest Mating Worlds

1. Same history, so raven parents have P

2. Deviation brings about mating conservative, so does not undermine theP-hood of the parents

3. Actual laws apply, so parentsP-hoodcauses P-hood, blackness, of offspring


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Separability

1. Physical separability: the fact of matingconsists of physical facts distinct from P

2. Causal separability: the fact of matingconsists of physical facts that are not

creating or sustaining causes ofP


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Contrast Case

If this raven had had some genetic defects,it still would have been black

Blackness not present in every evaluationworld because genetic defects not

separable fromP


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Why You Care About

Counterfactual

Su ort


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Overview

Regularities in the real world are very fine-grained

Knowledge of reasons for a regularityscounterfactual support provides compact

basis for knowledge of fine-graineddetails


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Overview

We care about regularities that offercounterfactual support because we careabout having a compact basis for learninga regularitys fine-grained details


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Fineness of Grain

All ravens are not black

Bleached ravensAlbino ravens

f


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Fineness of Grain

All ravens for which conditions Zhold, areblack

Zis very complex

Learning Zis learning fine-grained details

about a regularity

This is one-half of fineness of grain


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What Counterfactual Support


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What Counterfactual SupportDepends On

1. All actual ravens have P

2. Causal inertia of P3. Causal and physical separability of P

from relevant antecedents

4. Causal laws in virtue of which Pcausesblackness


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Simpler Case:Causal Antecedents

A d


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Antecedents

Antecedent of a generalization:All Fsare G

Antecedent of a counterfactual:IfAhad occurred, then Bwould have

occurred


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G d Thi K


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Good Things to Know

1. It is hotter above than beside a fire

2. Short term exposure may not causedamage

3. Damage more severe with length of

exposure

H T K Th


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How To Know Them

Dont just memorize factoids. Learn aboutmechanisms:

1. Damage comes from heat accumulation

2. Heat accumulation falls off with distance

3. Heat rises



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What Counterfactual SupportDepends On





S i l G li i


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Social Generalizations

If you have more material possessions thanother people, they will tend to envy you


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Non-CausalAntecedents

Roasted Raven Is


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oas ed ave sGood to Eat

The antecedent, ravenhood, does not dothe causing

It is some physical property Pof ravens thatmakes them edible

To Know Fine-Grained


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wDetails

1. Learn conditions under which ravenshave P

2. Learn conditions under which Phas itscharacteristic effect (taste, nutrition)

To Know Fine-Grained


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Details

1. Learn conditions under which ravenshave P

2. Learn conditions under which Phas itscharacteristic effect (taste, nutrition)

Learning Fine-Grained


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gDetails

In conditions Z, ravens have PHow to learn Z?

Method 1: learn about the mechanism thatcauses ravens to have P

Problem: Pis unobservable

Learning Fine-Grained


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gDetails

Method 2: Assume that most ravens innormal circumstances have P

Worry about the final phase, where theraven is removed from normalcircumstances: killing, dressing, cooking

Do these actions interfere with P?

It All Ab t I t f


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Its All About Interference

What actions interfere with or undermine aravens P-hood?

Those that manipulate things that are notseparable from P



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ppDepends On






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Summary

A ti


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Assumptions





Source of Knowledge of Fine-


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gGrained Details





C l i P t 1


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Conclusion, Part 1

To learn or predict fine-grained details of aregularity, learn the facts in virtue of whichit provides counterfactual support

These are actual facts that predict otheractual facts

Concl sion Part 2


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Conclusion, Part 2

Pay special attention to regularities thatprovide counterfactual support, becausewith these regularities, there is a compactbasis for learning fine-grained details


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