The A Priori Route from Essence to Necessity

Antonella Mallozzi

The Graduate Center - CUNY

The A Priori Route from Essence to Necessity

Birkbeck College, University of London

June 4th 2016

Desiderata for Modal Epistemology

(1) distinguishing metaphysical possibility

from other kinds of possibilities

(2) integrating Kripke's a posteriori

necessities

(3) respecting the fundamental

apriority of modal inquiry

The Epistemology of Metaphysical Modality

Conflicting demands?

A combination of EMPIRICAL + A PRIORI factors

KRIPKE'S NECESSITY-GENERATING PRINCIPLES

e.g. "If an object has a certain origin, it necessarily has that origin"

• embed essentialist criteria

• de re

• constrain metaphysical possibility given how things are at the actual world

Justifying the Bridge-Principles

A Priori Bridge-Principles

Scientific Investigation

enable the proper a priori inferences from actual to non-actual

Kripke's Inferential Model

for Knowledge of

A Posteriori Necessities

Connecting the actual to the non-actual.

Experience only gives us knowledge of what is actually the case

Info about the actual world

through empirical

observation & research

Kripke's A Posteriori Necessities

best case for interplay of

a posteriori + a priori

elements in modal inquiry

(necessity of origin, of composition, of fundamental kind, and of identity)

knowledge of the necessary a posteriori involves an a priori inferential step

A Realist Modal Metaphysics

instances of essentialist principles, as they involve essential properties

A Modified Analysis

Epistemic possibility: open a priori to a subject. Minimally logically-conceptually constrained

Metaphysical possibility: constrained by the actual world - by the nature of things at the actual world

Properties that objects have to have in order to exist at all

the more we learn about the world,

the more we learn about metaphysical modality

Kripke's Model

WE DISCOVER

GENUINE METAPHYSICAL POSSIBILITIES

Ex

(E) Ex

O

narrowing down the space of epistemic possibility to that of genuine metaphysical possibility

(i) If P, then necessarily P

(Necessity of origin, of fundamental kind,of substance...)

e.g. Ox

Ox

O

For Kripke, we know instances of (i)

“by a priori

philosophical analysis”.

(i) If P, then necessarily P

(modal; a priori)

‘If x has a certain essential property E,

then x necessarily has essential property E’

CONTENT

EPISTEMIC STATUS

(ii) P

simple actual fact that P.

we know P a posteriori via empirical experience.

e.g. Ox

(ii) P

(non-modal; a posteriori)

Which are the bridge-principles having the form (i)?

What makes it the case that the relevant bridge-principles have

a priori status?

(E) illuminates the content & justification of the bridge-principles and potential new cases

We need criteria for knowing which are the bridge-principles, and an explanation for how we could know them a priori

Just intuitive compellingness?

Why do such things as origins, substances, kinds are alleged to generate metaphysical necessities?

*Possible counterexamples?

How does it help to classify them as ‘essential properties’?

Modal intuitions being equal, some candidate instances of (i) do not seem to come out a priori.

Essences give us the desired criteria for metaphysical necessity

*species’ genetic structure

(iii) Necessarily P

P cannot be just any fact. How do we identify the ‘right sorts’ of facts to fit in our principles?

the bridge-principle ‘Gx Gx’ no longer looks a priori!

O

(modal [necessary];

a posteriori)

Ex

(E) Ex

O

Ex

(E) Ex

O

Relocating the epistemology of necessity at the level of the epistemology of essence?

FOCUS ON

ESSENCES

Essential properties

constitute the identity or nature of things.

They make things what they are

YES!

All the bridge-principles embed

an essential property.

The Significance of the Necessary A Posteriori

breaks down complex interplay of a priori inference + empirical input

categorical

individual

Is it because they embed such properties that they generate necessity?

respects the fundamental apriority of modal inquiry

revealing a new source of necessity against traditional conventional, logico-linguistic (analytic) necessity:

Kripke's necessity is de re - in things

material origin,

composition or substance

for particular artifacts

(this lectern, this table); biological origin for particular organisms

(Queen Elizabeth II)

The Bridge-Principle (E)

fundamental kind

(chemical structure, 'internal structure’, fundamental physical properties)

for kinds or categories of objects and phenomena

(water,tigers,heat)

The bridge-principles explain how we can move from knowledge of the actual world to knowledge of the non-actual, i.e., what is not an object of experience

Three Advantages

those necessities are grounded in the way the world is or in its intrinsic nature

empirical information needed to know certain necessities

provides the desired a priori step for modal knowledge

Combine Kripke's treatment

of a posteriori necessities with Fine's idea that metaphysical modality is grounded in essence

essential properties identify things— as individuals or as members of specific sets or categories

let's focus on these principles...

metaphysical thesis

(our world generates necessity)

epistemic thesis

(not everything that is necessary is a priori)

fits empirical bit (ii) of Kripke's analysis

more fine-grained & informative

a priori & safe from counterexamples

the search for essential properties turns on empirical investigation

specifies which sorts of facts P generate metaphysical necessity

constitutive a priori bond

between the notions of

essence,identity,and necessity

learning how things are,their behavior,

structural and intrinsic feature

We discover essential properties

Essences identify:

a thing has to have certain essential properties in order to be what it is

explains why instances of the bridge-principles hold

Science-oriented explanatory capacity makes it for a

naturalized

notion of essence

a priori that if a thing has a certain essence, it has it necessarily

What more can we say about these fundamental capacities for constitution and identification?

And how are these distinctive of essential properties as opposed to non-essential ones?

(E) meets the requirements of a scientifically driven modal inquiry

(E) gives modal inquiry robust foundation

(de re, in things)

& modus operandi

(from knowledge of essences to knowledge of necessities)

(E) preserves Kripke’s analysis and the fundamental a priori character of modal inquiry

More than intuitions!

Ex

(E) Ex

O

Essential properties play a special role

The generalized essentialist bridge-principle (E) improves Kripke’s analysis in a whole range of cases of the necessary a posteriori

They explain why things are in a certain way

They explain things' particular features and behavior—

both at a generic level and individually

A Puzzling Case?

Being a member of the human kind explains many other properties

(e.g., having a certain internal constitution, or being conscious), shared by all members of the same kind.

Having a certain biological origin, i.e., having certain parents, explains many other properties (e.g., the color of one's eyes,one's body shape).

Those features cannot be explained by non-essential properties

(e.g., ones' birthplace, one's favorite food).

The case of a posteriori identity statements involving proper names

O

Hesperus=Phosphorus

If the set of essential properties E of x constitute and explain

the identity and persistence of x,

x has to have E in order to exist at all

More and more

superficial and ‘ephemeral’ properties are explained by more and more

fundamental and ‘stable’

essential properties

The E’s are each necessary properties of x

Explanatory capacity

suggests a

continuous ontological hierarchy

(1) Hesperus=Phosphorus

(2) Hesperus=Phosphorus

(3)

De re metaphysical necessities are grounded in essences

‘Hesperus’ and ‘Phosphorus’ rigidly designate the same object, i.e.,the planet Venus. Although it is an empirical discovery that Hesperus is Phosphorus, it is a priori that if Hesperus is Phosphorus then necessarily Hesperus is Phosphorus.

Rigid designation tracks the

necessity of identity

O

What is metaphysically necessary for the things in our world is determined by what explains & preserves their very identity or nature, i.e., their essential properties.

Hesperus=Phosphorus

Things have to possess certain essential properties and maintain them across contexts and through change

to be the very things they are

Essential properties are

persistence conditions

—both temporally and modally

How does this case fit the purported analysis of the necessary a posteriori in terms of (E)?

Leave the philosophy of language aside,

esp. rigid designation

Is the necessity of ‘Hesperus=Phosphorus’ grounded in an essential property like the other Kripkean

a posteriori necessities?

Self-Identity?

‘Hesperus’ and ‘Phosphorus’ are names of the same object, the planet Venus, which of course is necessarily itself

Ex

(E) Ex

O

self-identity is definitely an essential property of objects—

just a trivial one, A=A.

O

However...

if ‘Hesperus=Phosphorus’ is an instance of ‘A=A’, then premise (ii) comes out obviously a priori not

a posteriori

Perhaps not just self-identity...

The empirical discovery that Hesperus=Phosphorus concerns

that one planet, Venus.

But it is also obviously different from one’s grasping the logical truth that Venus=Venus.

Perhaps this epistemic difference points to some further property of Venus? (essential & a posteriori)

Astronomers discovered that a certain heavenly body visible in the morning was in fact the same heavenly body visible in the same spot in the evening.

...It clarifies

• in what sense (ii) is a posteriori

• why strict self-identity, A=A, fails to capture Kripke’s point

Moreover...

• more to the content of a proposition than just the object it is about? (To the same Russellian proposition correspond two Fregean propositions)

• relevant information can be captured by descriptions,‘the morning star’ and ‘the evening star’

But we've slipped from the metaphysics back to the philosophy of language!

People used to refer to the first as ‘the morning star’ or ‘Phosphorus’, and to the second as ‘the evening star’ or ‘Hesperus’.

How does this help?

What they discovered is that there have never been two distinct stars in that position in the sky, but rather just one body (in fact, a planet),Venus, occupying a certain position in the sky both in the morning and in the evening.

Unfortunately, Venus’ actual position in the sky is not one of its essential properties.

It is a contingent fact that

morning star=the evening star.

In order for the analysis (E) to work, we need to identify some property E that is both essential to Venus and something we discover

a posteriori

A Dilemma

If the relevant essential property is self-identity, the case, although still necessary, no longer comes out a posteriori (for the necessity of self-identity is

a priori)

If we try to pick out some other property of Venus that we in fact discover a posteriori, the case no longer looks necessary (for the candidate properties, such as its position in the sky, seem plainly contingent)

Option #2

Option #1

We discovered that Venus has t

he property of

‘being identical to Venus’ or

'to Hesperus' or to Phosphorus'

Self-identity explains the fact that Hesperus=Phosphorus as well as the fact that Venus=Venus.

However, ‘Hesperus=Phosphorus’ is an a posteriori statement.

Everything is (a priori) self-identical,

but only Venus is

identical to Venus

(or Hesperus,

or Phosphorus)

How to build a general bridge-principle?

What's the property we discovered?

Thank You!

Antonella Mallozzi

The Graduate Center, CUNY

amallozzi@gradcenter.cuny.edu