Conceivability, Possibility, and the Inconsistent Triad
1
Conceivability,
Possibility, & the Inconsistent Triad
Three desiderata for modal epistemology
(i) distinguishing metaphysical possibility from other kinds of possibility within modal space
(ii) integrating the Kripkean essentialist principles & the necessary a posteriori
(iii) respecting the fundamentally a priori character of modal inquiry
Kripkean Challenge (KC):
Kripke's necessary a posteriori shows that what is a priori conceivable
may not be metaphysically possible
Desideratum (i):
focus on metaphysical modality
especially vs. epistemic modality
Epistemic possibility: open a priori to a subject independently of particular information about the world. Minimally logically constrained
Metaphysical possibility: concerns the nature or the identity of things or how actual things could have been or gone in a different way
Conceivability does not entail possibility as not everything we conceive is (metaphysically) possible
Desideratum (ii):
endorse Kripke's results
We can certainly conceive that Hesperus is not Phosphorus, although that is not a genuine metaphysical possibility
Certain necessities are rooted in the actual world and are only knowable a posteriori, via empirical investigation
Metaphysical possibility is constrained by the features of the actual world plus essentialist bridge-principles (the necessity of origins, composition/substance, fundamental kind, and identity)
Desideratum (iii):
close the gap between actual and non-actual
Empirical experience seems confined to only telling us about what is actually the case
An a priori step (inferential/intuitive) is required to explain how we can know the non-actual, i.e., what is not an object of experience
"Experience teaches us that a thing is so and so, but not that it cannot be otherwise"
The Kripkean bridge-principles are themselves a priori justified
Chalmers’ 2DModal Rationalism
is a promising attempt at satisfying desiderata (i)-(iii)
- distinguishes different notions of possibility, thus satisfying (i)
- aims to respect the Kripkean principles & data,
thus satisfying (ii)
- defends an a priori route to metaphysical modal knowledge, thus satisfying (iii)
Conceivability
Chalmers's Strategy:
- a conceivability-based route
Usually involves a variety of epistemic activities such as a priori reasoning, imagining, visualizing, supposing...
Alleged to entail or at least be evidence for possibility
Traditionally, our rational representational capacities can cast light on modal reality
Might not be confined to our actual capacities, but denote those of an ideal reasoner
distinguishing different notions of conceivability as well as possibility and connecting a kind of conceivability with a kind of possibility
Chalmers's Modal Rationalism
boosting conceivability & restricting possibility
I'll give you an account of how
conceivability entails
possibility that meets
KC!
(CP) Ideal Primary Conceivability Entails Primary Possibility
IDEAL CONCEIVABILITY
Virtual stance of a reasoner “free of all contingent cognitive limitations”
A kind of reasoning that cannot be weakened by further reasoning
No modal error & no counterexamples from cognitive limitations
PRIMARY CONCEIVABILITY
particular way we evaluate an expression’s primary intension
Pure 2-Dimensionalist
Combining two-dimensionalism (1) with modal monism (2)
Chalmers Vs. Kripke on modal metaphysics
the relevant notion of metaphysical modality is non-Kripkean and independent of the actual nature of things (how strange!)
Chalmers claims that
Kripkean metaphysics
“will put constraints on the space of possible worlds that are brute and inexplicable”
SECONDARY INTENSION
WHY??
only option for the two-dimensionalist who does not want to give up modal monism
The Kripkean constraints derive from the fundamental nature of our world. Its factual makeup + the essentialist bridge-principles determine the range of genuinely
metaphysical possibilities
PRIMARY INTENSION
Pure Two-Dimensionalism & Chalmers' commitment to Conceptual Metaphysics
Questions for Conceptual Metaphysics
This is just how nature is
“the concept of metaphysical modality itself has roots in the epistemic domain"
How are counterfactual possibilities “rooted a priori”
in the epistemic domain?
metaphysical modality itself has to be
a priori rooted in those primitive logico-conceptual structures and relations that hold regardless of how the actual world is
The idea of intensional structure may entail that modal truths are already somehow built into our expressions
How are the actually-factually constrained Kripkean possibilities ultimately an a priori matter?
The nature of the actual world as revealed by empirical investigation draws the boundary between the epistemic and metaphysical space—it justifies and explains that boundary
Why should
epistemic possibilities
be themselves
metaphysical possibilities?
For Chalmers, it is constitutive of an expression’s intensional structure that the referent of that expression have certain modal features...
where the relevant notion of modality is metaphysical
Anti-Realism?
taking a world W as counterfactual....
This allegedly guarantees cognitive access to the metaphysical realm via ideal a priori conceivability
taking a world W as actual....
What seems really “brute and inexplicable”
is granting that logical-conceptual coherence, however idealized, generates metaphysical possibility
and considering a sentence S...
Evaluating PRIMARY intensions
is a purely a priori exercise based on considerations of logical & conceptual coherence of the hypotheses under examination
Evaluating SECONDARY intensions involves considering a counterfactual world given
a posteriori info about how our world has turned out
2D Kripkean
When we consider a world as actual
we put aside empirical info about our world & virtually take the perspective of a speaker within the world under consideration
Monistic Kripkean
When we consider a world as counterfactual we reason along the familiar dimension of Kripkean or metaphysical possibility,
granting things at our world as they actually are
Two different strands of Kripkeanism emerge from the encounter with
two-dimensionalism
Combining Kripkean metaphysics (3) with two-dimensionalism (1)
Combining Kripkean metaphysics (3) with modal monism (2)
Two ways a Kripkean can respond to
Modal Rationalism, one closer and one farther from the 2D insights
Perhaps showing tensions within N&N itself?
Monistic K
Suspicious of the 2D framework,rejects its take on a posteriori necessities
Relevant examples are possible only in the loose sense that it is
not a priori that,e.g.,
Hesperus is Phosphorus
The possibility of Hesperus not being Phosphorus is illusory: it only corresponds to a subjective state of ignorance about certain astronomical facts
There is no distinct primary modality, no further dimension of possibility besides the metaphysical one
Epistemic possibility: merely a subject’s lack of information
not objective possibilities
“out there”
in the metaphysical realm
From the point of view of
the philosophy of language...
"is W a counterfactual possibility in which S would have been the case?”
For the Monistic K sentences expressing a posteriori necessities do not carry the extra-content needed to build the typical surrogate primary possibilities
"if W is the case, is S the case?"
The Kripkean Challenge itself seems misguided, since for the Monistic K there is no real way to conceive that Tully is not Cicero
Conceiving a case where Cicero is not Tully would be conceiving a case where that very individual fails to be himself. But how could that be?
Common ground between the two-dimensionalist and both the Monistic & the 2D Kripkean that cases like “Hesperus is not Phosphorus”,
“Cicero is not Tully”, “Water is not H2O”, etc.
are metaphysically impossible
While the two-dimensionalist is trying to press a de dicto reading of the case, the Kripkean pushes back the de re
How can you conceive that Cicero is not Tully?
Within the 2D framework
We struggle to deny the necessity of identity, and every time we seem to be doing it, we realize there is a shift in content
Logico-conceptual possibility:
empty structure that could be filled with any factual content as long as the resulting scenario is ideally coherent (after the ideal reasoner’s evaluation and approval, anything goes)
2D intensions should
preserve the modal distinctions that otherwise blur at the level of worlds
2D K has some sympathy for
two-dimensionalism. She is more flexible as to the philosophy of language and engages with Modal Rationalism
Would a Kripkean concede that they are still possible in some other sense?
Still, those distinctions do blur at the level of worlds
The Monistic K has a point here: since it is metaphysical modality that is at stake,
it is hard to see how the de re reading should not be the right one
"if W turns out to be actual, will it turn out that S?”
If metaphysical=logical modality,
then primary logical-conceptual possibilities become as such metaphysical possibilities
Metaphysical possibility:
governed by a number of additional constraints, i.e., principles of the Kripkean metaphysics
(what is metaphysically possible is determined by what is actually the case, given essentialism)
Inacceptable from a Kripkean point of view
Expressions may have some extra descriptive content and that opens up a further dimension of possibility
"if W had obtained, would S have been the case?"
That's why a priori conceivability does not
really help cast light onto metaphysical possibility
Similarity
Those are alien and unrelated to the actual world
The closer a world is, the more similar its metaphysical configuration to the actual world’s,
& the stronger the modal notions involved.
The farther we move from the actual world, the more
a posteriori features fade away,
leaving only superficial logical modal structure
Logical necessities as world-independent:
they hold regardless of how the actual world happens to be.
The very logical-formal conditions for a world to exist
(Fine's transcendental truths)
One needs to know how things really are and the relevant bridge-principles to grasp metaphysical possibilities
No clear sense in which those would embody
some possibility of Cicero not being Tully
Where Monistic K only sees a misdescription, 2D K sees an epistemic possibility
What one conceives as verifying a scenario doesn't really falsify an
a posteriori necessity
Degrees of modal force/
closeness to the actual world:
LOGICAL possibility weaker &
can handle scenarios far removed from the actual world
MONISM is a dangerous thesis for 2DK
The actual world with its properties, laws, and population retains complete priority in determining the space of metaphysical possibility
METAPHYSICAL possibility is loaded with the a posteriori deep features of the actual world. Stronger, but only ranges over the worlds close by
Although more flexible with
the philosophy of language,
2DK does not negotiate the metaphysics
Different objects, different content
The possible is constrained by the actual
For 2D K we can still speak of e.g. ‘Hesperus’ and 'Phosphorus' when considering controversial primary possibilities, since relevant descriptions or Fregean senses are part of the content of expressions.
Those give individuation-conditions for the referents (or determine the truth-values) of expressions along the primary dimension
2DK accepts a version of (CP) where primary possibility captures nothing more than a priori hypotheses, without further metaphysical commitments
By constrast...
2D rationalist metaphysics has purely a priori character
Qualitative difference between
logico-conceptual and metaphysical possibility
Rational logical-conceptual structures and relations
constrain the space of possibility a priori.
These are primitive or prior to the actual world (& to any possible world)
But also maximally permissive as to what is possible
Take "Cicero is not Tully".
In the 2D pic you need to admit that there are two people, Cicero and Tully,
at the world where this is verified
2DK expands the space of possibility, but keeps firm what is really the case given how things have turned out. Metaphysical possibility is still rooted in the actual world
Both the intrinsic & structural features of the actual world and the Kripkean essenialist bridge-principles are irrelevant to the content of primary possibilities
They have different sources, which excludes reductios and identifications
METAPHYSICALLY
POSSIBLE
WORLDS
LOGICALLY
POSSIBLE
WORLDS
MODAL DUALISM
Ideal a priori primary conceivability still does not give us access to the metaphysical modal realm
Evaluating different intensions is looking at
different possibilities
We conceive a sentence as T/F depending on how
the world at which the sentence is evaluated looks like
We conceive possibilities that could make
that sentence T/F
MODAL UPGRADING
Monistic K rejects
(1) two-dimensionalism, while retaining (3) a strong notion of metaphysical modality.
The space of possibilities for her covers only metaphysical possibilities, thereby her monism (2)
Answer to KC
Modal monism gives the unwanted result that even merely epistemic possibilities are verified by metaphysically possible worlds,just like any genuine possibility
"Cicero is not Tully"
1-INT
2-INT
logically = metaphysically possible worlds
(1) two-dimensionalism and (3) a Kripkean metaphysics cannot be conjoined with (2) modal monism. From the point of view of 2D K, two-dimensionalist modal rationalism can only be viable if paired with modal dualism
Kripkean sentences express multiple propositions
Primary intensions will be verified by worlds that are theoretically-qualitatively indistinguishable from all the other worlds
A posteriori necessities are secondarily necessary but primarily contingent
Ideal primary conceivability captures a priori ideally rational hypotheses verifying sentences' primary intensions, i.e., primary possibilities
(CP) Ideal Primary Conceivability Entails Primary Possibility
[2D Kripkean]
[Monistic Kripkean]
(CP)
but given modal DUALISM
}
(CP)
KC
Kripkean Metaphysics
KC
A priori access to Metaphysical Modality
An Inconsistent Triad
(CP) seems to meet the
Kripkean Challenge:
A moderate thesis?
Primary possibility is qualitatively different from secondary-Kripkean possibility
Given the refined notions of conceivability and possibility, (CP) seems plausible and even straightforward
No conflict between dimensions
& no (longer) conflict between our modal intuitions
Ideal a priori conceivability guides us reliably to perfectly coherent logical-conceptual possibilities (primary possibilities)
Modal rationalism fails
Severed Modal Rationalism
Possibility & necessity
are de re, in things
—-the things of our world.
The very nature of the
properties, laws, and population surrounding us determines their modal profile
But still metaphysically impossible that
Phosphorus is not Hesperus
Metaphysical modality is constrained by
the factual makeup the actual world plus the Kripkean essentialist bridge-principles
two-dimensionalism
A scenario verifies the primary intension of “Hesperus is not Phosphorus”
We can access a priori only epistemic possibilities
So from a Kripkean perspective, the 2Dist
The long-established Kripkean
a posteriori necessities are secured to belong
to a whole other dimension
Accordingly, modal inquiry begins empirically, informed by observation and scientific investigation
either gets the surrogate possibilities that he wants
-- but those are not metaphysical , merely epistemic (2DK)
expressions are modally complex and capture two dimensions of possibility: epistemic and metaphysical
“Hesperus is not Phosphorus” is primary possible
or gets some metaphysical possibilities, but with a different content
(not relevant intension) (Monistic K)
Either way, conceivability does not entail metaphysical possibility
From an ontological point of view, within the 2D-framework
logico-conceptual and metaphysical possibility are indistinguishable
Still, the 2D framework works with that very distinction
Only two can be
true at a time
For Chalmers,
2-dimensionalism
will restore the
golden triangle of
constitutive connections between meaning, reason, and modality
that was built by the progressive efforts of Kant, Frege, and Carnap—
and later crashed by Kripke
Kripke's necessary a posteriori
A two-sided idea
those necessities are grounded in the way the world is or in its intrinsic nature
empirical information needed to know certain necessities
metaphysical thesis
(our world generates necessity)
epistemic thesis
(not everything that is necessary is a priori)
there is only one modal space or source of necessity
metaphysical possibility & necessity are constrained by the
a posteriori features of the actual world + Kripkean bridge-principles
A new source
of necessity vs.
traditional conventional, logico-linguistic
(analytic) necessity
Kripkean metaphysics
modal monism
Different sources of necessity?
But if metaphysical modality is Kripkean and de re,
primary possibilities cannot be themselves metaphysical
...Why is the
Kripkean
unhappy?
2-dimensionalism has a more
'generous' attitude to what is possible and enriches modal space
with further possibilities
Not an option for Chalmers.
For he endorses
modal monism (2):
there is only one
source of necessity & logical-conceptual possibility is coextensive with metaphysical possibility
From a certain point of view, it does seem so
But those are descriptive a priori possibilities entailed by the content of the primary intensions, that only depend on language + logical entailment
Primary modality is de dicto modality
and it is largely independent of how things actually are
The scenario depicting “Water is not H2O” that both Chalmers and the Kripkeans conceive has probably the same features:
a world with some sort of liquid substance that looks exactly like water & has the same role as actual water
But for Monistic K this is horrific.
What a possible world could look like both intrinsically & structurally is determined by how the actual world looks like
Chalmers wants to say that we can call that “water” and still deny that it is H2O
The Source of the Inconsistency
Two-dimensionalists and Kripkeans work with opposite criteria for metaphysical possibility
But 2D modal rationalism tries to satisfy both criteria
The Kripkeans, instead, either do not want to call it “Water” but something else, whatever it is (Monistic K), or accept to call it “water” but only insofar as the described scenario is not a metaphysical possibility (2DK)
A terminological issue?
We cannot just associate familiar
words to different things
when that involves a deep metaphysical change
Perhaps a misunderstanding concerning the term “metaphysical”?
(a change in the structure of a fundamental kind, or that leads to give up transworld identity—the necessity of identity)
From Chalmers’ point of view,both primary and secondary possibilities are metaphysical
In this sense, Chalmers’s modal metaphysics is purely a priori and quite flimsy
And primary conceivability only tells us that if things are so and so,
then certain counterfactuals follow,
without addressing the issue of
how the modal realm 'really' is
...But this rather reveals a world-view
Is it just that Chalmers is willing to call
e.g. “water” something that
the Kripkean is not?
For Chalmers,the metaphysical structure of possible worlds can change
as long as
the scenario that verifies this modified world
is coherent
In the 2D monistic metaphysics
modal distinctions belong
to the semantic domain
We can just call those different things at the
modified world with the same old words,
as long as we are careful not to fall into
a contradiction
Whether something is
primarily/secondarily possible
depends on where an intension is
verified/satisfied
within the same space of worlds--
--not on which worlds are genuinely metaphysically possible as opposed to mere epistemic possibilities
Modal dualism could provide the qualitative distinction between sources of necessity & corresponding possibilities that would help reconciling two-dimensionalism (1) and Kripkean metaphysics (3)
The inconsistency
But Chalmers'
two-dimensionalism comes instead with modal monism (2)
two opposite notions of metaphysical modality:
Chalmers' (combining (1) + (2)) vs. the Kripkean (3)
(3) can only be compatible with either (1) or (2) not both
2D modal rationalism does not accommodate the Kripkean notion of metaphysical modality that aims to integrate at the level of the secondary dimension
A further issue for 2D Modal Rationalism
2-D MODAL RATIONALISM...
May give us a general 'formula' to construct perfectly coherent hypotheses but those might have very little to do with how the modal realm 'really' is
Playing the game at the semantic level with the 2D intensional apparatus
does not answer the Kripkean worries.
We cannot just reduce metaphysical modal differences to semantic-linguistic ones
Primary conceivability only casts light on primary possibility...