I
I shall start with a few remarks concerning the meaning of the terms in question. Still
nowadays, ›a priori‹ is sometimes used in the sense of ›expressing
ontological laws‹ or in Barry Smith's words: »The family of [ontological, PB]
necessitation-relations extends […] to fill out the entire sphere of what,
traditionally, had been seen as the domain of a priori knowledge« (Smith 1992, 309).
Smith is committed to Husserl. In the 3. of his Logische Untersuchungen Husserl
declares those pure laws as being synthetic a priori, in which the occuring non-formal
terms are not formalizable salva veritate (Husserl, XIX/1, 260). Unfortunately, and
despite my sympathy for Husserl's ontological view, such a claim does not tell us what
kind of knowledge really is at stake. Smith at least seems to be willing to defend the a
priori-view by appeal to »an innate capacity to discriminate between instances of
categories«. Moreover, he continues that »hand in hand with this innate capacity goes
the ability to grasp the associated relations of necessitation« (320). There is no point
in denying some kind of innate capacity. Nevertheless, what such an appeal does not
explain is in what cases and by what criteria a discrimination made is true or false.
Furthermore, there is at least one hypothesis which cannot be based upon innate capacity
without falling into a vicious circle, the hypothesis of having the innate capacity
itself. In addition, there are those like David Armstrong who prefer to talk about
ontological laws in terms of inference to the best explanation. One of the aims of this
paper is to argue that ontological laws are a priori. However, I am not ready to follow
Smith or rationalists such as BonJour (1992). I restrict the use of ›a priori‹
strictly to epistemic contexts. It is a common place today that much confusion was
generated by logical positivists by their treating ›analytic‹ and ›a
priori‹ as synonymous or as coextensional. Instead the analytic/synthetic-distinction
is a semantic, the a priori/a posteriori an epistemic disctinction. The former yields
information about reference or applicability of the expressions in question whereas the
latter tells us what kind of evidence or thruth is involved. An analytic sentence is true
even if its relevant expressions do not refer or are not applicable in the given world
whereas any synthetic sentence, be it a priori or a posteriori, has to be applicable in
order to be true.(1) Semantics provides us with a necessary
condition. Synthetics a priori have to be applicable in some senseful way. Applicability
on the one hand and evidence or truth on the other are most certainly supposed to be
mutually dependent but they are obviously categorical different.
II
That there are no synthetic propositions a priori was the shared belief of classic
analytical philosophers. That there are no synthetics a priori de re has been the
shared belief of antimetaphysicians since Kant. Whereas a metaphysician claims that
statements like
(1) The Universe is the only natural system with no environment.
(2) The Universe is the only strictly necessary substance.
(3) Particulars are bundles of universals.
have to be true or false, antimetaphysicians will at best be willing to accept these
statements as general elements of a grammar (Wittgensteinians) or as ideas (Kantians) or
as elements of a categorical framework to organise our experience (Körner 1984).(2)
They believe that propositions like (1)-(3) have to be excluded from the class of true or
false sentences. For the sake of argument let us take it for granted that
antimetaphysicians are wrong and that our examples are synthetics a priori. In that case,
we can start with two observations:
(i) Example (3) obviously indicates that synthetics a priori cannot be necessarily true
as it has normally been demanded of aprioris. First, there are alternatives to (3).
Second, (3) cannot be true because it would presuppose the principle of the identity of
indiscernibles to be necessarily true — which it is not (cf Armstrong 1978, chap. 9).
Since (3) can be true or false (acceptable or deniable), criteria such as certainty or
infallibility can barely get generally accepted for aprioris.
(ii) The realistically minded metaphysician will defend some concept of nonepistemic
truth. She will not accept the reduction of truth to warranted assertibility or to some
meaning-based truth-conditions. Furthermore, she will call for extralinguistic
truthmakers. Unfortunately, it won't help much to simply claim that our examples are true
or false independent of our means of knowing. She will claim the same in regard to a
posteriori truths. The demand for extralinguistic truthmakers does not dispense her from
giving an account of evidence for the propositions in question. Metaphysicians who claim
to work in a field of what could be called total science are obliged to give an account of
the kind of knowledge they are expecting to find.
Despite their antimetaphysical attitude it may be worth reminding the reasons that Kant
and the logical positivists had for rejecting the synthetic de re. Some may still
be good, from others there may be lessons to learn in regard of a defensible account of
synthetics a priori.
First, think of the notion of ›force‹. Suppose what seems to be a good
working hypothesis that the term ›force‹ stands for some generic trait of being.
Now, if you accept the rationalist's basic assumption that the mind has some direct
awareness or acquaintance of necessary facts about the nature of being you are expected to
have some insight in basic facts about force such that you can grasp the true propositions
about it. Moreover, as a realist, you need extralinguistic entities of any kind whatever
to make your sentences true. Unfortunately, and this is true even for those like me who
favour a non-Humean view on causation, as far as ›force‹ is concerned there is
no argument at hand demonstrating that we are acquainted with the truth-maker in question.
It is a well-known fact that both Hume and Kant got influenced by this point.(3)
It undermines any attempt (such as BonJour's 1992) to restore a rationalist position since
in order to defend his view, the rationalist would have to show, (i) why in the case of
›force‹ there is no acquaintance with this generic trait of being although in
other cases the acquaintance is supposed to be available and (ii) whether there is any
case of acquaintance in necessary facts outside of logic at all.
Secondly, Kant adopted from rationalism an orientation towards certainty and
undeniability. Kant believed in the coextensionality of ›a priori‹, ›strong
general‹, ›necessity‹ and ›certainty‹ (cf. Critique A XV,
B 3/4, »apodiktische Gewißheit«), where certainty means, as is again proposed by Van
Cleve (1992), ›not truly deniable‹.(4) Kant
explicitly excludes hypotheses from the domain of the apriori (A XV). Now remember our
examples. Maybe (1) is a candidate for not truly being deniable. If someone claims that
the universe has an environment we will readily treat what we earlier called
›universe‹ and what we now declare as its environment both as parts of the
Universe, and so on. Nevertheless, someone who believes in God's creation of the Universe
may deny (1). Therefore, it seems most reasonable to look upon (1) and possible
alternatives as general hypotheses. (3) too is a general hypothesis based upon assumed
ontological entities such as universals. Certainly, universals will never be empirically
identified. The hypothetical character of at least (1) and (3) indicates that things could
be just the other way round than Kant suggested. Kant's criticism on rationalism was not
decisive enough as he still accepted its orientation towards certainty. If we are willing
to give up the coextensionality of certainty and a priori it may become reasonable to work
alongside the suggestion that all synthetics a priori are hypothetical.
Thirdly, Kant never denied that all knowledge stems from experience. Instead he could
be read to take into consideration the difference between context of discovery and context
of justification originally (Critique B 1). Despite the experience-dependence of
knowledge there may be a class of statements for which no justification is available by
inductive generalisation. We can restate Kant's point in Quineian terms. It may be the
case that progress in science will force us to look for new logical systems. However, this
will never change the fact that criteria for justification of logical systems cannot be
empirically grounded. If we exclude the problem of whether there are a few very general
nonfallible principles such as noncontradiction or consistency Quine could be done justice
without any commitment to empiricism. Aprioris are true or false. However, any apriori
which we are ready to give up, i.e. we believe to be false will always have to be replaced
by another apriori.
Fourthly, the logical positivists rejected the synthetic a priori for two reasons. On
the one hand, they refused it because of the reference of ist advocators to an inner sense
as an extralinguistic mean of evidence. Not only are there no acquintances with
extralinguistic truthmakers for aprioris de re there also is no extralinguistic evidence
for aprioris de dicto. I agree with that. On the other hand, the synthetic a priori de
re got eliminated by logical positivists because (i) they favoured sensualism, (ii)
they held the semantic doctrine that meaning determines reference and finally (iii) they
accepted the rationalist's orientation towards certainty too. As all of this premises got
seriously criticized none provide good reasons for eliminating the synthetic a priori de
re any longer — at least if one avoids appeal to inner sense or awareness of
necessary facts.
So far, we get the following results regarding our defence of an account of synthetics
a priori:
(i) There is no direct acquaintance with extralinguistic entities in question
guaranteeing that we grasp true propositions .
(ii) Nondeniability or certainty are not necessary conditions of the apriori.
(iii) Hypotheses may very well be the general form of aprioris.
(iv) For all synthetics a priori, if a synthetic a priori will be given up it will be
replaced by another synthetic a priori.
Still, nothing has been said about what kind of knowledge we gain with synthetics a
priori.
III
In his Ontological Investigations Ingvar Johansson proposes the following
threefold distinction (1989, ch. 16):
| |
analytic |
synthetic a priori |
synthetic a posteriori |
Applicable
Non-applicable |
NT
NT |
NT
F |
T
F |
where T stands for ›true‹, F for ›false‹ and NT for
›necessarily true‹. He claims that synthetic statements a priori are false just
in case their subjectterms do not refer, i.e. are not applicable. On the contrary, if the
terms in question are applicable then the statements will be necessarily true. Although I
agree with the thesis of fallibility of synthetics a priori (5)
Johansson's suggestion needs refinement in order to become acceptable. Remember our
examples:
(1) The Universe is the only natural system with no environment.
(2) The Universe is the only strictly necessary substance.
For (1) and (2) to be true ›Universe‹ has to be a referring expression, a
denoting proper name. Moreover, (2) implies that ›Universe‹ is a referring
expression in every possible world. I take (2) to function as a statement where by pure
rational means a rigid designator is introduced. Of course, it is not a rigid designator
like ›Socrates‹ or ›water‹. There is no demonstrative baptism.
Nevertheless, it is a rigid designator as (i) it holds its reference for all possible
worlds, (ii) there is no meaning in (2) involved, and (iii) science, cosmology, tends to
discover as good as possible what the Universe does consist of. It is the accepted
cosmological model at a given time which provides the meaning such that a analogue kind of
identity-statement to ›water is H2O‹ becomes available:
›The Universe is xyz‹, where xyz stands for the group of the fundamental
assumptions of a cosmological model.
I should say more about that. However, consider a sentence, well-known in todays
cosmology:
(4) The Universe is homogenous and isotropic.
As ›Universe‹ is always applicable, according to Johansson, (4) would have to
be necessarily true. Unfortunately, cosmologists teach us that the Universe may not be
totally homogenous. (4) is at best an idealized approximation and that seems to go well
with Johansson's concept of truthlikeness (or partial truth). The difficulty is that
truthlike statements cannot be accepted as necessarily true. Again, the appeal to a
nonepistemic concept of truth won't help. The point is not that we will never have
adequate empirical criteria to decide conclusively, but that a statement like (4) does not
need to be necessarily true only because the subjectterm is applicable. What Johansson
should say or presumably meant to say is that if the referring expressions in the
statement are applicable and if the latter is true then it expresses some kind of
necessity de re: in regard to physics, that the physical world could not be
different, in regard to ontology, that the general structure of being could not be
different. It is not truth by itself which is necessary, but that a true synthetic
statement a priori de re would express some necessary fact about reality.
Let us elucidate the point further. Remember
(3) Particulars are bundles of universals.
For a challenge, we can attack the bundle-view or we can deny that there are
universals. Suppose for now that there are universals i.e. that ›is a univeral‹
is applicable. Unfortunately, Johansson's suggestion again fails to be satisfying. Despite
our acceptance by hypothesis that ›being a universal‹ is applicable only one of
the following sentences can be true:
(5) For all x, if x is a universal then necessarily there is at least one instance of
x.
(6) For all x, if x is a universal then there may be no instance of x.
Applicability is not accompanied by ›necessarily true‹. Rather, we have a
hypothetical or conditional situation: if either (5) or (6) is true, than the true
sentence will express a necessary fact about reality. The same goes for another famous
example:
(7) For all x, if x is an instantiation of a colour then x is extended.
I want you to interpret (7) as a synthetic statement.(6)
In that case, if (7) is true it will express a necessary dependence between colour and
(spatiotemporal) extension. Unfortunately, the sentence once again is not necessarily true.
Suppose we advocate what Armstrong tells us to be the best version of a trope-theory, the
suggestion that tropes are pointlike non-extended qualities (Armstrong 1989, 115). In that
case (7) is a false proposition as an elementary colour-instance is not extended. All we
get are hypothetical truths depending on the chosen ontological framework. Applicability
as well as truth itself are assumed by hypothesis. Either the synthetic a priori functions
as a primitive or it is a consequence of primitives.
If the truth of synthetics a priori is not guaranteed but hypothetically assumed the
question arises about how to evaluate between competing proposals. Surely, apart from
standard criteria such as economy, comprehensiveness, non-ciricularity, we will expect
some explanatory goal regarding basic features of our experience (or better: our
scientific world picture). If we agree with the latter a second question will arise. If
actually all synthetics a priori are hypothetical would it not be more reasonable to
prefer what Peirce called abduction instead of synthetics a priori? Peirce himself had an
empiricist's view of abduction. His first and third »cotary propositions« restrict
abduction to perceptual judgements.(7) I believe that Peirce
let unconsidered that there are two kinds of abductive hypotheses at hand.
The well-known example »Water is H2O« may serve as a paradigm
for the empirical type. On the left hand side we have a demonstratively introduced
kind-term, on the right hand side a component of a scientific theory for which evidence is
added by predictions, observations and experiments. Abductive hypotheses are empirical (a
posteriori) iff demonstratively introduced (first order) terms and predictions,
observations or experiments are involved.
It is evident that the examples discussed hitherto do not fit in this scheme. Although
›Universe‹ functions as a rigid designator (i) the entity is not demonstratively
baptizable and (ii) neither observations nor experiments are available to support direct
evidence for statements of the form »The Universe is F«. There is no point in claiming
with Peirce that abductive statements concerning the Universe shade into some perceptual
(or experimental) judgement about the Universe itself. The best what could be done is to
confront (but not test) the consequences of a cosmological model with an observable region
or the consequences of a naturalistic hypothesis such as (1) with the accepted scientific
outcome at a given time. Nor does it make sense to talk of adding evidence for ontological
statements via predictions, observations or experiments. We can think about ways for
testing quarks, but not for testing universals or natural classes. Moreover and contrary
to ›Universe‹, applicability for ontological terms is dependent upon the
ontology defended. However, once assumed they become applicable in all possible worlds.
Furthermore, there is a kind of demonstrative definition involved, although of a higher
order: call ›a property‹ each case of being red, being round, having a certain
mass etc. Universals or tropes and the like are then introduced in order to explain
properties. As the list of properties is open and also dependent upon scientifically
accepted candidates, the standard adequacy conditions of an account of properties(8)
will not suffice. Any ontological theory, i.e. any synthetic a priori has to be confronted
with the best available empirical knowledge at a given time.
A more detailed account of the outlined adequacy conditions would exceed the scope of
this paper. However, in addition to the results of the preceeding section we get that,
given we acknowledge the a priori/a posteriori distinction as epistemic, the discussed
statements should be regarded as synthetics a priori. On the one hand they actually have
to be considered as hypothetical: if they are true, they will express a necessary fact
about the reality. On the other hand the standard criteria for aposterioris are
unavailable in evaluating them. Nevertheless, there are rational criteria at hand. Plato
would have said that the second best way is available only to human minds. Synthetics a
priori have to have explanatorial power in regard of the best empirical theories at a
given time. They have to be best explanations — they are abductive — but their
means of justification are not grounded in experience — they are a priori. Certainly,
they do not provide truth-criteria for empirical theories. General metaphysics can teach
us what the most reasonable theory about the most general structure of being would look
like. It is not nothing to know the pro's and con's for universals or the pro's and con's
for a naturalistic world picture. Although such a result is not what rationalists believed
to be the achievement of general metaphysics it is far more than antimetaphysicians have
ever been ready to accept.
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