Chapter 23
Metaphysics in Analytic Philosophy
Peter Simons
1 Introduction: Loss and Restitution
Among those with an outdated or partial conception of analytic philosophy, the whole
movement is associated with the rejection of metaphysics. But such rejection,
however motivated and justified, was never the sole prerogative of analytic
philosophy, nor was it ever the majority view within that movement. Early analytic
philosophers engaged in metaphysics without compunction, and it was only during
the “middle period” of the 1930s–1950s that, under the influence of logical positivism
and ordinary language philosophy, metaphysics was first rejected and later
marginalized. It is this publicity-catching period that is often taken pars pro toto. We
shall chart the origins, critique and re-establishment of metaphysics within analytic
philosophy.
Whichever philosophers are taken to be the parents or progenitors of analytic
philosophy, whether Russell and Moore, Frege, Bolzano or even Leibniz, all of them
were fully engaged in metaphysics. In Leibniz and Bolzano we have a monadology of
mental or physical atomic substances, in Bolzano and Frege we have a timeless
Platonic realm of abstract objects guaranteeing the objectivity of logic and meaning,
in Moore and Russell we have a world of many material objects existing
independently of minds.
As analytic philosophers grappled with the problems in the foundations of
mathematics and engaged in consolidating the new logic, attention shifted to the
language medium and the metaphysical dimension faded from attention.
Wittgenstein’s trenchant prohibitions on nonsense found resonance with continental
European logicians and philosophers of science whose suspicion of metaphysics
derived from empiricist tendencies in Germany and France, and these crystallized in
the Vienna Circle’s attempts to demonstrate the senselessness of metaphysics.
These efforts quickly emerged as self-defeating, but a general suspicion of
metaphysics as reactionary and backward-looking lingered through analytic
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philosophy’s establishment as a dominant movement. Never completely extinguished
even in the analytical movement, metaphysics began to re-emerge to prominence in
the 1950s with the work of Quine, Strawson and others, and the increasing importance
of logical and linguistic semantics afford a ready avenue for the re-establishment of
metaphysics as the ontic counterpart to language, as it had been among the early
analytics.
The rediscovery of genuine and unsolved metaphysical problems at the hands
of several analytic philosophers gradually led to a de-emphasis on the linguistic and
semantic approach to metaphysics, and in a reverse of the linguistic turn, metaphysics
was pursued in wide circles in relative autonomy. As the new millennium dawned, it
was clear not only that metaphysics was no longer dead, but that its resurrection as
analytic metaphysics was one of the more remarkable developments in philosophy in
general and in its analytic strain in particular.
2 Frege and Logical Objectivity
We start with Frege. Never a philosopher by avocation, still less a metaphysician,
Frege’s mission was to prove Leibniz right against Kant that the concepts of
arithmetic and analysis are purely logical, and that the laws of arithmetic have the
same objectivity and certainty as those of logic, being logical themselves. This was
logicism. Unburdened by the weight of logical tradition, Frege reinvented logic for
this purpose, introducing an astonishing range of innovations including modern
quantification, truth-functions, the functional analysis of sentential complexity,
yielding in passing a treatment of relations, and the development of a logical system
of unprecedented precision and clarity.
On the face of it this appears relatively remote from metaphysical speculation.
But Frege’s insightful analyses rested on certain key assumptions that turned out to be
ontological in nature, in particular his view that proper names such as numerals and
other mathematical constants designate abstract individuals, that function names stand
for abstract functions, and that clauses designate two special entities called the True
and the False.
Frege’s assumptions about the harmony between the grammatical categories
of expressions and the categories of entities they designate appear to be, and in some
respects are, naïve, but he held to them in order to secure logic’s objectivity against
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what he construed as the twin diseases of his time: psychologism and formalism.
Psychologism, which was a particular embodiment of the Humean naturalism and
empiricism then dominant in Germany, claimed that the laws of logic are to be taken
in scientific manner as the laws of thought, that is, the contingent empirical laws
governing actual thought-processes. Frege saw that this would lead to logical
relativism, allowing alternative thought-processes to have their own, equally
legitimate “logics”, undermining the Western tradition of the objectivity of
knowledge from Plato onwards. It would also give the laws of logic, which Frege saw
as a priori, an inferior status as mere empirical generalizations and undermine the
distinctness of arithmetic and other non-geometric parts of mathematics he considered
as analytic. Frege’s position and arguments, seconded more ponderously but more
influentially by Edmund Husserl, soon pushed psychologism aside.
Formalism on the other hand treated mathematics as a mere game with
symbols, having no reference to any objects and having at best incidental usefulness
in application. Since many games are possible, the certainty of mathematics is
undermined because the applicability of mathematics is left unexplained, or regarded
as mere good fortune, or a matter of convention or convenience. In dispute with the
more advanced formalism of David Hilbert however, Frege’s trenchantly ontological
interpretation of mathematical concepts and axioms failed to emerge as a clear
winner. This undecided outcome was to affect later philosophy of mathematics and
influence the metaphysics debate.
In the course of consolidating his position in logic and mathematics, Frege
incidentally developed a powerful and still widely influential philosophy of language,
distinguishing in meaning between sense and designation, and upholding the
objectivity of the contents of thought as abstract propositions or “thoughts”. Like the
numbers and other mathematical entities, such propositions and their parts were
construed Platonistically as neither material nor mental, but of a “third realm”, thus
involuntarily reprising the forgotten position and arguments of Bolzano more than
half a century earlier. Like Bolzano before him and Popper after him, Frege faced the
metaphysical difficulty of explaining how the mind could “grasp” such transcendent
abstract senses, a problem he never satisfactorily resolved.
Another problem that Frege left to others to resolve was how to deal with
contradictions that emerged in his logic and were highlighted by Bertrand Russell.
These concerned Frege’s assumption of “value ranges”, special abstract objects
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corresponding to functions, which were to be the designations for numerical and other
terms. In his later work Frege dropped value ranges without replacement, but
persisted with the general Platonistic framework for logic and his three-way
metaphysics of the material, the mental and the abstract.
3 Moore, Russell and Realism
It was Bertrand Russell who first notified Frege of the inconsistency in his system,
discovered when Russell was grappling with the foundations of mathematics from a
similar and independently formulated logicist standpoint. Unlike Frege however,
Russell came to his Platonism through a struggle, the struggle against the absolute
idealism of Bradley and others then dominant in English-language philosophy.
Bradley was the dominant British philosopher of the day, and his Victorian update of
Parmenides, Spinoza and Hegel in a monism in which the only true object is the
Absolute was the staple of Cambridge philosophy when Russell and his contemporary
G. E. Moore were studying there under the idealist John McTaggart. Bradley’s
monism was an unabashedly metaphysical position, motivated by logical
considerations and supported by arguments attempting to show the inconsistency of
diversity. The incredible epistemological consequences of this idealism, surfacing
also in McTaggart’s arguments against the reality of time, pushed Moore into
rebellion and rejection with several papers, notably his 1899 “The Nature of
Judgment” and his 1903 “The Refutation of Idealism”. The former rejected Bradley’s
absolute idealism by distinguishing between objects and concepts, though in a way
that is hard to credit today, while the latter rejected Berkeleyan subjective idealism.
This led Moore into a greater respect for unsophisticated opinions, coming to imbue
his subsequent philosophy with its twin characteristics of common sense realism and
a tendency to indulge in copious and minute analysis of the terms in which
philosophical problems are expressed. Of these, the former has generally (though not
universally) survived, while the latter has tended to be preserved in spirit but sidelined
in practice by logico-linguistic analysis more akin to that of Frege or Russell.
Fired by Moore’s rebellion, Russell thankfully embraced a luxuriant realism,
allowing every name or term to stand for something, often in many and varied ways.
Along the way Russell discovered a kindred spirit in the Austrian philosopher Alexius
Meinong, and for a while their positions were close. But Russell never agreed with
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Meinong’s acceptance of objects with inconsistent characteristics, and sought ever
more refined ways to show that Meinong’s assumptions led to logical contradiction.
In this first enthusiasm for realism, Russell was able to treat mathematical objects as
equally existent alongside more familiar material ones, while Moore was happy to
construe objective values such as goodness as something indefinable outside us, to be
grasped by a special kind of intuition. In so doing, Moore and Russell were not only
working in partly recognized parallel to continental thinkers such as Brentano,
Meinong and Husserl: they were also storing up again the access problems of prior
Platonists.
After the long dominance of idealism in Britain and America, the turn to
realism in the early 1900s brought about a seemingly permanent shift away from the
Hegel–Bradley line. It was not only the principal analytic philosophers who
contributed here: apart from the Austrians previously mentioned, a similar movement
among the American New Realists reacted against American idealism, and older
contemporaries such as Samuel Alexander, C. D. Broad and G. F. Stout also
influentially promoted various versions of realism. Of these the most considerable
was Alexander, whose work influenced not only Whitehead but also later generations
of Scottish and Australian analytic philosophers.
4 Logicism and Logical Atomism
Russell’s pursuit of logicism led him not only to his mathematical Platonism but to a
decisive engagement with the new logic, apprehended by him first through Peano, but
soon diverted through detailed if fallible study of Frege. The years of struggle to find
a solution to the logical paradoxes dominated a decade of Russell’s life, during which
time he completed his early masterpiece The Principles of Mathematics and embarked
on the more ambitious realization of logicism in collaboration with his former teacher
Alfred North Whitehead, resulting in the three-volume (and yet incomplete)
monument Principia Mathematica (1910–13).
Russell’s favoured solution to the paradoxes was his theory of types, sketched
in a crude version for classes in 1903 but fully developed for propositional functions
in an article of 1908. Like Frege, Russell realised that his paradox arose through an
uncritical acceptance of all singular terms for classes as actually designating such a
class. While the theory of types undercut this assumption by restricting the
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meaningful phrases that could enter into such expressions, Russell went further and
looked to treat all expressions for classes as only appearing to designate. This “no
class” theory became the official version in Principia, but the way had been prepared
by Russell’s twin occupations with Meinong on the one hand and Frege on the other.
Rejecting both terms for impossible objects like the round square and Frege’s twolayered theory of meaning as sense and designation, Russell contrived to find a new
way to account for descriptive terms like ‘the author of Waverley’ as entering into
truths without standing for (denoting) objects. The resulting theory of definite
descriptions had a threefold effect. Despite the obscurity of its initial exposition, it
came to serve as Ramsey’s “paradigm of philosophy”. Secondly, it did serious work
in Principia, in that nominal terms for classes were used but taken as not
fundamental, being analysed as more or less elaborate quantifier phrases. Finally, in
the hands of Russell’s collaborator Whitehead, where as part of a Grassmanninfluenced method of “extensive abstraction” it was used in a crusade against
imperceptible geometrical entities like points, lines and surfaces, it inspired Russell to
go on to “expose” ever more singular terms as not really designating expressions, but
as overt or covert descriptions to be “paraphrased away”. The result was that the
exuberant realism of Russell’s early years was progressively pared back as more and
more kinds of entity such as people and cities were “replaced” by Principia-inspired
logical constructions out of a more limited range of entities such as sense-data and
Platonic universals. The logical method was now functioning as the cutting edge of
Ockham’s Razor, which Russell wielded with relish to simplify his ontology.
From 1911, Russell’s logico-philosophical investigations came increasingly
under the influence of the young Austrian engineer Ludwig Wittgenstein, whom
Frege had advised to study with Russell. Imbued with linguistic and aesthetic
puritanism alien to Russell’s English liberalism, Wittgenstein persuaded Russell to let
him take over development of the philosophy of logic, which Wittgenstein, in
common with others, found imperfectly, perhaps incoherently stated in Principia. His
austere account of the world and the role logic plays in our knowledge and
understanding of it emerged as Wittgenstein grappled in largely solitary struggle with
questions of the nature of representation, truth and the proper nature of logic. The
early Notes on Logic, dictated for Russell’s sake, state many of Wittgenstein’s
positions in clear form, and Russell let them work on his views. Cut off from contact
by the war, Russell and Wittgenstein independently developed similar but importantly
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divergent visions of the world and logic’s role, Russell in the sparklingly readable
1918–19 Lectures on Logical Atomism (a name he had invented in 1911),
Wittgenstein in the painstakingly formulated and painfully published but ultimately
more influential Tractatus Logico-Philosophicus of 1922.
While both works, the latter in particular, lay massive stress on language and
logic, they share a broad metaphysical viewpoint and plan. The world consists
primarily not of objects but facts, and it is facts that correspond to true propositions
and by existing make these propositions true. Whereas an object like Socrates is
named by a name, a fact is the ontological counterpart of a true statement or its
associated that-clause, e.g. that Socrates taught Plato. Some apparent names do not in
fact name at all, as in the theory of descriptions, while not all true statements
correspond to their own facts, for example the truths of logic and mathematics. In
such cases the truth is to be explained by the role of logical connectives like negation
and conjunction, which are truth-functions, and do not stand for anything, whereas for
Frege they stood for logical functions.
Beyond this convergence however, there are notable disparities between
Russell’s and Wittgenstein’s versions of logical atomism, with metaphysical
implications. Russell accepts negative, conjunctive and general facts, corresponding
to true negations, conjunctions and universal quantifications. Wittgenstein rejects all
facts as constituents of reality apart from those corresponding to true atomic
propositions, which consist in what Wittgenstein calls the existence of a state of
affairs. Russell takes sense-data and universals as the designata of genuine singular
and general terms respectively, while Wittgenstein steers clear of such internal
differentiation among the components of states of affairs. Pursuing a trenchant and
ultimately confused notion of analysis, Wittgenstein pronounces a priori that all
objects (nameables) in the world are atomic, or lacking in proper parts, and exist
independently of what is the case, thus coming close to ancient and Leibnizian
atomism.
Most importantly for the sequel, Wittgenstein has a radically more austere
conception of what a meaningful language can be like. Language serves the
representation of empirical reality, the facts, or natural science, and any form of
expression that is neither doing this nor (like logic) is a by-product thereof, is literally
meaningless. This includes, by a disconcerting reflexive move, the statements of the
Tractatus itself, which are incoherently understood as “enlightening” nonsense by
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comparison with the unenlightening nonsense that Wittgenstein dubs ‘metaphysics’.
Russell never bought this deflationary analysis, and suggests in his published
Introduction that languages might come in a hierarchy whereby we can talk about one
language using another, thereby anticipating metalogical moves initiated by
Leśniewski and Tarski shortly afterwards. Nevertheless, Wittgenstein’s insistent
opposition to such a way out led him not only into disagreement with Russell but also
to conceive of himself as having finally solved the problems of philosophy, or rather,
showing that there are no real philosophical problems, and leading to his
(temporarily) abandoning philosophy.
5 The Rise and Fall of Logical Positivism
The most famous clash between metaphysics and analytic philosophy occurred in and
around the Vienna Circle of logical positivists and associated thinkers. Logical
positivism, as manifest most prominently in interwar Vienna but echoed with varying
emphasis in other parts of Europe, notably in Berlin, did not emerge ex nihilo. Three
streams fed it. One was Wittgenstein. A second stream, generally underemphasized in
English-language depictions of positivism, was the background of scientific
approaches to the human and social sciences, as advocated by Mill, Comte (from
whom the word ‘positivism’ was taken) and Marx. The third was a general
enthusiasm of German-speaking philosophers for a form of empiricism inspired by
Hume and other British empiricists. This arose initially in reaction to Kant, Hegel and
other German idealists and the anti-scientific tendencies of German romanticism.
While later eclipsed in academic philosophy by the rise of German neo-Kantianism, it
informed the work of German scientists such as Weber, Helmholtz, Kirchhoff and
Boltzmann, whose philosophical education tended to be better than their counterparts
elsewhere, and was bolstered outside the physical sciences by the enthusiastic take-up
of Darwinism in Germany by Haeckel and others. Such scientists tended towards a
metaphysically low-key, instrumentalist understanding of their work, emphasizing the
procedures of observation and measurement and regarding theories as regulative
instruments rather than as depictions of reality.
The most prominent philosopher–scientist representing this position was the
Austrian physicist–physiologist–philosopher Ernst Mach. Mach pursued a
metaphysically deflationary phenomenalism, treating theories as ways to streamline
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the move from observation to prediction, and disallowing them any ontological
import. Mach carried his position forward in print, formulating a version of
Newtonian mechanics lacking Newton’s “occult” forces and imperceptible space and
time, and thereby inspiring the young Albert Einstein. Appointed to a chair of the
History and Philosophy of the Inductive Sciences in Vienna, Mach soon retired due to
ill health, remaining as a radical member of the Upper House, and through the strong
influence of his non-Marxist radicalism in Russia inspiring a furious ad hominem
critique by Lenin.
Mach’s influence in Vienna extended to local scientists and from 1911 a trio
consisting of mathematician Hans Hahn, physicist Philipp Frank and social theorist
Otto Neurath met regularly in Viennese cafés to discuss Mach and the foundations of
science. After World War I Mach’s chair was filled by the German philosopher
Moritz Schlick, who had trained as a physicist with Max Planck and shared many of
their views. It was the socially adept and urbane Schlick who initiated regular
Thursday meetings in Vienna that became known as the Vienna Circle.
Not himself a logician, Schlick moved to bolster logical competence in Vienna
by appointing a rising young German logician Rudolf Carnap, who like himself had
worked on the borders between philosophy and physics. Carnap had studied with
Frege and Husserl and was well versed in the new logic. Carnap’s first major book,
The Logical Construction of the World (usually called by its short German title, the
Aufbau) was an heroic attempt to marry the logical methods of Frege and Russell with
the phenomenalism of Mach and the first-person constructive perspective of Husserl
and in the process scientifically “recover” the world, no less.
Having read and been forcibly struck by the Tractatus, Schlick arranged for
the Circle to study the book. The closing remarks on metaphysical nonsense struck a
resonant chord with Neurath and Carnap, and Schlick undertook to introduce the
socially extremely inept Wittgenstein to the Circle. His persuasive powers brought the
two sides together but the meetings were not a social success and soon Wittgenstein
restricted his contact to Schlick and Waismann. Nevertheless the combination of the
Circle’s scientistic attitude and Wittgenstein’s dismissive attitude towards
metaphysics resulted in the first attempt since Hume to formulate a clear principle by
which bad metaphysics (which in their view was all of metaphysics) could be exposed
as such. This was the much-vaunted verification criterion of meaning, according to
which a statement is meaningful if and only if some observation could count as
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verifying it. Setting logical truths and falsehoods aside in Wittgensteinian fashion as
marginal cases, it proceeded to lay waste to all other forms of discourse, including
theology, ethics and aesthetics, as well as traditional metaphysics.
One important fact about this criterion is that it works with the whole sentence
or statement as a unit of meaningfulness, this a legacy of Frege’s and Wittgenstein’s
insistence on the priority of sentences over names. Another is that the verifiability is
clearly one in principle, not restricted by mere practical limitations. Neurath, who was
opposed to all metaphysics in principle as an anti-democratic hangover from feudal
and bourgeois societies, seized on verifiability, as did Carnap. The latter expounded
metaphysics in Wittgensteinian fashion, but more systematically, as resulting from
misuses of language that produce pseudo-statements that look like statements of fact
but in reality are not. These would include statements of value, of theology, and of
metaphysics. Philosophical problems are pseudo-problems that arise precisely through
such a misuse of scientific language. Carnap in particular identified the practice of
speaking about language misleadingly as though it were about the things designated
rather than the words, as a source of ready misunderstanding. His remedy was to
always, when in doubt, perform “semantic ascent”, the move to talking about
language rather than its objects.
The verifiability criterion did not, some renderings to the contrary, debar
scientists, or indeed logical positivists, from meaningfully using terms that have
ontological import. Someone who states in biology for instance that such and such is a
recessive gene is thereby implying that among the things that exist in the world are
genes. Nor did its adoption rule out ontological disagreements among positivists. Ever
the Marxist, Neurath interpreted scientific statements as being about material bodies
rather than the collections of sense data that phenomenalists such as Mach or Russell
thought made up the world. Neurath also persuaded Carnap that this was the best way
to treat the basic statements of science. Nevertheless “victory” over Carnap in an
ontological dispute was not a heavy metaphysical matter, because Carnap took the
alternatives of materialist (physicalist) and phenomenalist languages to be a matter for
convenience and pragmatic decision rather than finding out which one correctly
depicted the world. There is some evidence that this kind of light-touch attitude to
what the basic names designated also represented Wittgenstein’s view at the time he
was interacting with the Vienna Circle.
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A generally scientific attitude to philosophy was shared not only by the logical
empiricists around Hans Reichenbach in Berlin, but also by various groups in France,
Britain, Scandinavia, and Poland. Contacts between Warsaw and Vienna proceeded
mainly at the level of logic, involving Carnap, Tarski and Gödel. The Lvov-Warsaw
school of philosophy and logic never bought the Vienna Circle’s anti-metaphysical
stance: their philosophy can best be described as anti-irrationalist, and involved
respect for logic, language and science rather than a rejection of metaphysics. While
metaphysical positions among Polish analysts varied widely, from the extreme reism
of Kotarbiński via the Husserlian moderatism of Ajdukiewicz to the lush Platonism of
Łukasiewicz, they were prepared to disagree metaphysically and regard such disputes
as substantive rather than as a matter of linguistic choice. In this way they resisted the
excesses of positivism and pointed the way forward to the post-war revival.
The positivist criterion of meaningfulness was attacked almost immediately by
Ingarden and others as reflexively self-defeating, since it was itself unverifiable but
supposedly meaningful. The effects of this critique can be observed at painfully close
range in the tortuously backtracking Foreword to the 2nd edition of the English
positivist A. J. Ayer’s influential Language, Truth and Logic, a work which for many
anglophones encapsulated the excitement and ultimately the failure of the positivist
anti-metaphysical crusade. In 1934 Karl Popper proposed his alternative falsifiability
criterion, not of meaningfulness but of scientificity: scientific statements are
falsifiable, unscientific ones, including metaphysical statements, are not. Like
mathematics, metaphysics is assigned by Popper a potentially constructive
“framework” role. Like the verifiability criterion, but for different reasons, Popper’s
criterion is unsuccessful, but that did not stop him vehemently opposing Carnap’s
stance on induction and probability, nor did it inhibit him later from subscribing to a
three-realm ontology like those of Bolzano and Frege.
Two incidental disadvantages of the attempt to find a blanket recipe for
disallowing metaphysics, both already painfully apparent in Wittgenstein’s own
formulation, but endemic to the enterprise, were that the purveyors of the criterion
would be tacitly making metaphysical assumptions while claiming not to do so, and
that such a blunt instrument was powerless to discriminate bad metaphysics from
good. The former worry was addressed in part by Quine. The latter may be illustrated
by two contemporary works that both put forward revisionary metaphysical positions,
but which stand the test of subsequent scrutiny to different extents. On the one hand
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there is Heidegger’s Being and Time of 1927, proposing a new ontology of humanity,
and on the other hand there is Whitehead’s Process and Reality of 1929, which puts
forward a panpsychic cosmology of interrelated events. Both are difficult works to
interpret, but whereas Heidegger’s later prose grew in opacity, Whitehead’s was
elsewhere more translucent. Carnap had little difficulty in lampooning Heidegger’s
‘Das Nichts nichtet’ as syntactic nonsense, but much of Whitehead’s prose, while
grammatical, is at least as tough to interpret. Yet neither is a priori nonsensical.
6 Ordinary Language and Descriptive Metaphysics
The re-entry of Wittgenstein into philosophy in England, his growing influence, and
the parallel development of linguistically-oriented philosophy in Oxford under Ryle
and Austin kept the focus in British philosophy of the 1930s–1950s on the role of
language in formulating and solving or dissolving philosophical problems.
Wittgenstein’s reluctance both to theorize systematically and to make general
statements about what exists kept attention diverted from metaphysical questions,
while Ryle’s attempts to linguistically undercut Cartesian dualism and Austin’s
examination of the minutiae of the English lexicon likewise kept attention on matters
of language and methodology. It was principally during this period that the myth of a
permanent revolution in philosophy, eloquently supported by Russell’s dramatizations
of his intellectual development, gained sway as a reading of the previous half-century.
However there were indications for those with an eye to see that metaphysics
had not disappeared completely even in these circles. Ryle was after all denying the
existence of souls, and proposing that the mental be given a dispositional–behavioural
explanation. Austin recommended a phenomenology of language as a preliminary, not
the be-all-and-end-all of philosophical theory, and in his theory of truth opposed
Strawson’s deflationary performative account of truth in upholding a subtle and
sophisticated version of the correspondence theory, returning to Russellian facts. With
the publication in 1959 of Strawson’s Individuals, subtitled An Essay in Descriptive
Metaphysics, stressing the categories of body, person, space and time, it would appear
that metaphysics was making a comeback. Both the appearance and the subtitle were
subtly deceptive. Strawson’s metaphysics, like that of his mentor Kant, is retained
within an epistemological straitjacket. We are constrained to refer to bodies in space
and time because that provides a framework for identifiable reference: the argument is
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transcendental, not ontological. Likewise Strawson’s characterization of the useful
distinction between descriptive and revisionary metaphysics is a distinction between
two different kinds of conceptual scheme: one consonant with everyday common
sense and linguistic usage, the other attempting to replace that scheme with another.
His preferences clearly on the side of the descriptive, Strawson refuses in Kantian
fashion to pose the question which scheme might be correct of the world. This is
Königsberg with an Oxford accent, Metaphysics Lite rather than full-strength. The
implicit target of Strawson’s insistence on the ahistoricity of descriptive metaphysics
is his predecessor Robin Collingwood, who had not only embraced metaphysics
against the trend of the time, but had insisted that the ultimate presuppositions that
make up metaphysics may and will shift as science and human culture develop.
7 Scientific Language and Ontological Commitment
Although the word ‘metaphysics’ largely remained taboo in analytical circles, the
notion of ontology began to be cautiously used, particularly in the context of the
discussion launched by W.V.Quine, of ontological commitment. Quine had visited the
Vienna Circle and other European centres of scientific philosophy. He was especially
impressed by Carnap, whose Logical Syntax of Language he had seen in preparation
in Prague, and by Tarski, whose lectures he had attended in Warsaw. A student of
Whitehead and a staunch proponent of the merits of formal logic in philosophy, Quine
initially worked on streamlining the logic of Principia by new interpretations and a
new set theory. The ontological side of his work emerged in the 1930s, probably as a
result of his visit to Warsaw in 1933. A dominant logician there was Leśniewski,
whose lectures Quine attended. Leśniewski, who had taken his understanding of
quantification from Peirce and Schröder, regarded it as acceptable to quantify any
variables in logic, while still believing that only individuals exist. Quine, whose
understanding of quantification came from Whitehead and Russell, on the contrary
took variables, after the semantic fashion he had newly learnt from Tarski, as varying
over a domain of objects, different sorts for different kinds of variable. While
sympathizing with Leśniewski’s view that only individuals exist, Quine disagreed that
quantifying sentential and predicate variables was an innocent procedure. Quine later
took Leśniewski to be proposing a substitutional interpretation of quantifiers. This
verdict is both anachronistic, since the distinction between substitutional
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quantification, where the quantifier ranges over expressions, and objectual
quantification, where they vary over what the expressions designate, was at that time
inchoate, and it also misrepresents Leśniewski’s view, albeit that this too was then
semantically unarticulated.
The upshot was that Quine formulated his principle of ontological
commitment: that a theory formulated in the language of predicate logic is committed
to those entities that the bound variables of the theory have to range over in order for
sentences in the theory to be true. So individual variables range over individuals,
sentential variables range over propositions, predicate variables over properties and
relations, and set variables over sets. Thus Quine’s most famous slogan: “To be is to
be the value of a variable.”
Thus equipped, a scientifically minded philosopher may scan a properly
regimented scientific theory and discern to what it commits its proponent,
ontologically. Ever inclined towards nominalism, Quine put aside all but nominal
variables, but finding the expressive powers of a purely reistic theory too
impoverished, he “embraced” sets, in order to give his scientific language sufficient
expressive power to encode the mathematics needed to do modern science. Sets he
preferred to properties, propositional functions, propositions and possibilia because
they have clear criteria of identity: sets are the same whose elements are the same.
This second principle, “No entity without identity”, became Quine’s second slogan
and a watchword for scientifically-minded philosophers.
It is worth contrasting Quine’s views with those of his admired mentor
Carnap. Carnap always took the choice of a scientific language to be one of
expediency rather than externally mandated principle. For some purposes, it might be
beneficial to quantify variables apparently designating mere possibilia, or states of
affairs, or numbers. No such choice has the strong metaphysical consequences that
Quine’s criterion appears to entrain, because we are always able to swap this language
for another. Convenience, not the world, dictates the choice. While within a particular
language we can say what exists according to that point of view, which is an internal
question, but there is no saying what exists from a language-external point of view:
that is an external question, and in logic, a principle of tolerance reigns, which means
that no metaphysical conclusion is to be taken seriously. Carnap’s earlier concession
to Neurath over physicalism was thus a matter of decision rather than principle, and
14
his parting advice to his students at the end of his career remained uncompromisingly
anti-metaphysical.
Quine’s advocacy of ontological commitment seems to place ontology on a
firmer footing than Carnap’s utter rejection, but this appearance also turned out to be
deceptive. Because Quine, rejecting both the Vienna Circle and Popper, regarded
scientific theories as confronting reality as a whole, rather than sentence-by-sentence,
the ultimate test of a scientific theory is its general fit with our experience rather than
its correspondence to a supposedly independently existing linguistically unformulated
reality. All we know about the world is what our best scientific theories tell us: there
is no higher court of appeal, no metaphysics that can trump a scientific result.
Metaphysics does not deal with a higher realm and is not a priori: it deals with the
same domain of experience as everyday and scientific life, and its concepts are
distinguished solely by their greater generality. No statement, not even one of logic,
let alone one of metaphysics, is guaranteed forever immune from revision. Admittedly
it would take a lot more to persuade someone to give up the law of contradiction than
to give up the belief in say, dark matter, but the principle is the same.
Not all terms in a theory function alike: some are more remote from sensory
experience than others. This is where Quine’s holism undermines his ontology. We
imagine a world exactly like ours, except that the objects that the basic names denote
are permuted one-to-one. Provided this permutation remains undetected, as it must if
properties and relations are left invariant by the permutation, it makes no difference to
science. In other words, which objects are which is not a scientifically determinate
affair. This, supported collaterally by the underdetermination of theory by observation
and measurement, is ontological relativity. All that remains invariant are the numbers
of objects to which a theory may be committed and the relational role they play within
the theory. They have no “identity” beyond this. So there is for example no fact of the
matter as to which atom was the first to split in the explosion of the Hiroshima bomb.
Quine ends up closer to the Vienna Circle than the ontological terminology would
suggest. One way to see this result is that it is the extension of the indeterminacy of
identity from a realm where makes prima facie sense, namely pure mathematics, to
science in general, where it is less clear. Since Quine denies that there is a difference
in principle between mathematical and empirical theories, this is wholly acceptable
for him.
15
The remoteness of ontology from ordinary as well as scientific language was
reinforced by Quine’s famous doctrine, expounded in his 1960 Word and Object, of
the indeterminacy of translation, according to which different semantic interpretations
may be placed on a corpus of utterances without one being correct at the expense of
the others. By compensatory readjustments, my surprised shout of “There goes a
rabbit” may be interpreted variously as “It rabbiteth yonder” or “Rabbitish processes
are locally concrescent”, with differing ontologies, yet equally apt as responses to the
scene, and no one will be any the wiser.
8 Re-Emergence
We have seen that despite Quine’s terminology, his use of the term ‘ontology’ and its
cognates does not constitute a full-on revival of metaphysics in the classical style.
While differing in various respects from the “atheistic” position of Carnap, it remains
like Strawson’s a very light-touch form of metaphysics, as would be expected from
the pragmatist that Quine was. A heavier-duty approach to metaphysics, returning it
to the kind of central status it had during ancient, medieval and early modern
philosophy, emerged from different currents of analytic philosophy, starting in the
1950s and continuing to the present.
The first of these was, ironically, logical semantics. This developed from
modern logic in the 1930s. Its principal architect was Alfred Tarski, whose seminal
work The Concept of Truth in the Languages of the Deductive Sciences appeared in
Polish in 1933, in German in 1935/36, and finally in English in 1956. In this, the most
important work on truth since Aristotle, Tarski showed how to provide a paradox-free
delimitation of the true sentences from certain formalized languages, starting a debate
about the correct account of truth that continues unabated to this day. Central to
Tarski’s theory is the idea that we need a number of objects, of type varying
according to the language, to provide the raw materials for names to name, predicates
to be true of, and for quantification to be interpreted over. The details are not
important: what is important is that we need objects, and that they play a role in fixing
truth. Neurath immediately and presciently recognized this as the Trojan Horse by
which metaphysics could re-enter scientific philosophy via the back door of
semantics, and vehemently if unsuccessfully opposed it. Tarski’s teacher Leśniewski
16
opposed it for the quite different ontological reason that it makes use of objects
Leśniewski rejected, namely sets.
As the limitations of Tarski’s languages began to be widely felt, and as the
model theory which his work had initiated was more fully developed by himself and
other mathematicians, it began to be mooted that ordinary language, with all its
complications and non-mathematical features, might be susceptible to the same sort of
treatment. Carnap had already initiated such wider work on logical semantics in the
1940s, and this work, especially his 1947 Meaning and Necessity, encouraged
Tarski’s student Richard Montague to broaden the semantic treatment to ever more
ambitious parts and features of English and other natural languages, resulting in
Montague Grammar, where a wide variety of entities are invoked as the semantic
values of expression such as indexicals like ‘I’, ‘here’ and ‘yesterday’ and modals like
‘possibly’.
Modal logic also provided the motor for developing the notion of a possible
world, as a “hidden” index accounting for the truth-values of modal propositions as
distinct from merely categorical ones. Inspired by Leibniz, the idea of a possible
world, mooted by Arthur Prior and others, came to full prominence in the semantics
for modal logics developed by Saul Kripke. Kripke’s Naming and Necessity (1970)
offered a semantic account of proper names at variance with the then standard
descriptivist view, proposing that proper names designate the same individual in
every possible world (in which they designate anything at all). Reinforced by this
powerful semantic vision, and gaining support for their ability to do semantic work,
possible worlds soon entered the vocabulary, and in some cases also the ontology, of
many analytic philosophers.
The semantic route to metaphysics was not the only one that philosophers
took, though it was numerically the most influential. Even during the heyday of
positivism and its aftermath, pockets of metaphysical research could be found in
analytic philosophy. One such was in Poland, where the pre-war prominence of exact
philosophy was eradicated neither by Nazism nor by communism. Another was in
Iowa, where a former Vienna Circle member, Gustav Bergmann, reflecting on the
failure of positivism, suggested that logical positivism’s failure showed in its poor
implicit metaphysics of phenomenalism. Inspired by earlier metaphysical Europeans
such as Brentano, Meinong, Husserl, Frege and Russell, Bergmann and his students
returned to a face-to-face confrontation with metaphysical issues such as the existence
17
of universals, the nature of facts, and how conscious beings differ ontologically from
inanimate objects. A further centre of metaphysics from the 1950s was Australia. The
founder of Australian analytical empiricism, the Scot John Anderson, had heard
Alexander and had rejected both positivism and Oxford analysis. Anderson’s student
David Armstrong joined with Scot Jack Smart, Englishman Ullin T. Place and
American Charles B. Martin to debate Ryle’s behaviouristic reduction of
consciousness, and to reject it in favour of a metaphysical thesis: the identity theory of
mind, according to which conscious mental processes simply are processes in the
brain. Ironically or not, this is a view adopted in 1916 by the first Australian
philosopher of note, Samuel Alexander. While this view sparked a massive and
ongoing debate on mind and body, and spawned a host of ever diverging positions, its
frank and direct adherence to a metaphysical thesis provided a clarion example to
other would-be metaphysicians struggling to lift themselves clear of the ties of
semantics.
Of these so-called Australian materialists, the one true Australian amongst
them, David Armstrong, continued his metaphysical work in other areas, upholding
an Aristotelian realism of universals, whose interrelations account for laws of nature,
subscribing to a Russellian ontology of states of affairs, which are given the important
semantic task of making sentences true, and construing possible worlds
reductionistically via the recombinability of the components of our actual world.
Taken together, Armstrong’s various treatises constitute a systematic metaphysics in
the same general vein as that of Alexander or Whitehead.
9 Consolidation and Flourishing
It is hard to pinpoint a time when metaphysics re-emerged triumphant as a fully paidup member of the Philosophical Disciplines Club. Quine, Strawson and Kripke all
have claims to have rendered metaphysics acceptable in polite society, while
Bergmann and Armstrong offered a new old-fashioned directness in their approach to
metaphysics. However if a single work can be identified that got almost all theoretical
philosophers discussing metaphysics again, it was David Lewis’s 1986 treatise On the
Plurality of Worlds, a trenchant and articulate defence of modal realism in the face of
“the incredulous stare”, blank ontological inability to accept alternative worlds as real
18
as our own. While making few total converts, Lewis’s realism and the vocabulary of
counterparts, haecceitism, and intrinsic duplicates that he deploys to defend it, have
had philosophers “doing” metaphysics with little thought for the linguistics. While
Lewis’s ultimate motivation is that of Montague or Kripke, to provide a proper
semantics for modal logic, he is eager to recommend his solution for its own
metaphysical sake, and as part of a systematic vision of the world as a Humean
mosaic of independent particulars. Around that work Lewis also wove a dense tissue
of metaphysical discussion involving properties and relations, structures, sets, states
of affairs, persistence and change, all of which instructs subsequent philosophers that
it is both profitable and acceptable to engage in metaphysical speculation, which of
course is what his view is.
At the same time as Lewis was getting incredulously stared at, other
metaphysicians were broaching topics either untouched for generations or wholly
new. From this point, some time in the 1980s, analytic metaphysics was a going
concern and could be pursued unaccompanied by shamefaced apologies or reference
to the positivist past of analytic philosophy. Indeed as historical concerns began to
inform analytical philosophy, both in discovering its own lengthening past and in
discerning themes pursued in common with previous traditions and epochs, from
fourth century Greece to 13th century Paris to 19th century Vienna, the sense of
analytic philosophy as archetypically antithetic or indifferent to metaphysics was
replaced by a sense of the positivist era itself as atypical and aberrant.
As our story approaches the present, it becomes harder to pick out enduringly
salient works and figures, so we shall confine our attention to some salient topics,
problems and positions that have been discussed in more recent analytic metaphysics.
One concern, voiced by Lewis in passing, has been to account consistently for
the idea of intrinsic change in a persisting individual, as when a leaf changes from
green to yellow, or a man changes from sitting to standing. Five solutions have been
proposed to this problem, three of them discussed by Lewis, two by others. The first
is that a temporary feature like redness in a leaf is not an intrinsic property but a
relation to a time. Lewis rejects this out of hand, though it implicitly informs much of
the “at t” style of analysis: the leaf is green at t1 but red at t2. A related approach, but
subsumed by Lewis under this heading, denies that the indexing of a property to a
time makes it into a relation. Lewis also rejects out of hand the extreme idea that only
the present exists, so there is no inconsistency to worry about. Perhaps surprisingly,
19
this view, known as presentism, has enjoyed much discussion and some popularity in
the philosophy of time, where it contrasts both with eternalism, the idea that all times
are equally real, and other views whereby the past grows or the future shrinks.
Lewis’s preferred solution is that the leaf, the man and other persisting things have
temporal parts or phases as well as spatial parts, so the redness and the greenness
belong to different temporal parts of the same temporally extended thing, much as a
chessboard has some black spatial parts and some white spatial parts. Defenders of a
neo-Aristotelian ontology of substances deny that these have temporal parts, and look
for alternative explanation along the lines of the indexing solution.
A fifth option, deriving largely but not exclusively from earlier work of
Donald C. Williams, is to take properties not as universals but as dependent
individuals, tropes, so that change of an object from green to red consists merely in
the replacement of one colour-trope, of the green kind, by another of the red kind.
This view consciously invokes ancient and medieval theories of individual accidents
as its forbear. Trope theories of individuals, their properties and kinds have grown in
popularity as offering a nominalistically acceptable alternative to Aristotelian theories
of properties and change, making fewer ontological commitments than their realist
alternatives.
In the assessment of the ontological commitments made by a theory or even a
sentence, while Quine’s criterion continues to be popular, another criterion widely
invoked is that of the required truth-makers of a proposition. The idea of a truthmaker, any object which by existing makes some proposition true, is explicit in
Russell and Whitehead’s logical atomism but already present in medieval philosophy.
A truth-maker is any object whose existence is sufficient for a truth: the truth is
conversely ontologically committed to such truth-makers as are necessary for it to be
true. A lively debate among proponents of this view, first arising in the Australian
discussion of Rylean dispositions, has ensued as to what kinds of entities play the
truth-maker role, for example whether it is necessary to invoke states of affairs for
this purpose, and whether every truth must have a truth-maker.
The Lewisian temporal-part account of persistence, anticipated earlier by
Bolzano, Carnap, Whitehead, Leśniewski and others, draws attention to the notion of
a temporal part, and the metaphysical importance of the part–whole relation and its
formal theory, mereology has steadily risen, returning it again to levels found among
earlier philosophers from Anaximander to Russell, before the positivist deluge and the
20
hegemony of predicate logic and its standard set-theoretic semantics blunted
ontological sensibilities among analytic philosophers. Mereology has not remained a
neutral tool however: like set theory itself it has served as a springboard to further
metaphysical controversy. In particular the question has been raised, most notably by
Peter van Inwagen, as to when a collection of objects go to compose or make up a
further object. This composition question has given rise to two surprisingly extreme
answers, namely ‘always’ and ‘never’. The associated metaphysical theories, called
compositional universalism and compositional nihilism respectively, have
commanded much support and even more attention despite their lack of consonance
with standard ways of speaking and thinking, an indication that large numbers of
metaphysicians are unafraid to be revisionist in their views in support of satisfyingly
rounded metaphysical theory. Among the many possible compromise positions
between these two extremes, one still uncompromising one is van Inwagen’s
organicism, according to which the only mereologically complex objects are
organisms. Ants exist, tables do not: apart from organisms, there are only simples
(mereological atoms). The extent to which such a view comports with science,
including not just biology but modern physics, is a moot point.
It has become apparent that philosophers, whether “straight” metaphysicians
or philosophers of science, have become increasingly prepared to let metaphysical
considerations enter into their assessment of the nature and status of science and its
theories and objects. Metaphysics has to this extent “gone applied”. For example a
seemingly parochial debate among various brands of evolutionary biologist as to the
nature of species and the unit of evolutionary selection has both informed and been
informed by considerations of set theory, mereology and other seemingly esoteric
metaphysica. In mathematics as well as physics one form of realism about their
respective subject matters, entertained for different reasons in each case, is structural
realism, according to which the objects dealt with by mathematics (or physics) have
no intrinsic properties or natures and no identity apart from their position in relational
structures. The extent to which such a position is both coherent and mandated by
considerations of the nature of the subject is a matter of ongoing debate, with some
proponents of mathematical structuralism insisting their considerations are a priori
and a modern kind of logicism, while proponents of physical structuralism claim their
position insulates them against the pessimistic meta-induction, the idea that in the
21
long run all scientific theories are false. Structures are precisely what survive
scientific change invariantly, is the claim.
While moves to apply ontology and metaphysics to various disciplines have
come only sporadically from philosophers, a more urgent requirement for
sophisticated ontological analysis is posed by the burgeoning of large databases in
medicine, engineering, automated language processing and the world-wide web,
where initial models drawn directly from computer science proved incapable of
reflecting the ontological complexity both of the domain and of the knowledge of
practitioners in the discipline. While what data modellers call ‘ontologies’ are
implementation-independent conceptual models with implementable interfaces rather
than philosophical theories of what there is, their adequate design calls for just the
kind of considerations that metaphysicians have been deploying in the name of their
discipline since Aristotle, so the equivocation is more than a mere pun.
Metaphysics never remains cut off from other philosophical problems, and one
of the most persistent of these has been the mind–body problem in all its forms. While
attention has shifted from the identity or otherwise of neural processes with mental
processes, problems of interpreting the two marked characteristics of the mental,
namely consciousness and intentionality, have provoked a rash of metaphysical
speculations of variable generality. While attempts to reduce or eliminate
consciousness and intentionality in favour of physicalistically construed processes
have met with little success and less acceptance, philosophers keen to stake out a
solution have not only formulated the concept of supervenience, or covariance across
domains, as a potential way to bridge the differences, but have returned more recently
to G. H. Lewes’s concept of emergence, last prominent in Alexander and other
philosophers of the 1920s, as a way forward. As with all debates in the area, it is wise
not to hold one’s breath for a resolution. The difficulties of explaining the emergence
of consciousness from matter have prompted a revival not just of mind–body dualism
but also of the Leibnizian idea of panpsychism, that all beings, down to fundamental
particles, have the germ of consciousness in them. Thus in metaphysics no theory
from the past appears to be so conclusively rejected as to be inconceivable for future
use. Even the monistic holism of Hegel and Bradley exerts some pull, as does the
Leibnizian rejection of relations as genuine constituents of reality.
The question as to what genuinely or fundamentally compromises the world
appears to be at the heart of metaphysics, but it too has given rise to two different
22
kinds of controversy. One is whether there is a difference between two kinds of
existence, real or genuine existence on the one hand and mere or ordinary existence
on the other. Once again, this is a view that seemed to have faded into the past in the
wake of Quine’s criticisms, but has acquired a new lease of life. As analytical
metaphysicians comes to grips with a lengthening tradition of largely unresolved
controversies, a second and more fundamental issue gives rise what has come to be
called metametaphysics, which discusses the question whether the ontological
disagreements to which metaphysics is prone are genuine disagreements at all, and
whether there is a right and a wrong answer as to which if either of two disagreeing
parties is correct. This raises, in a new key, the disquiet that gives positivism its
attraction, namely the idea that metaphysical disputes are somehow not genuine
disagreements, but constitute a kind of shadow-boxing. As before, there are the
relativists who recapitulate Carnapian tolerance, and there are the strict neo-positivists
who instruct metaphysicians to restrict their activity to interpreting the results of
corroborated science. As to which science is corroborated and what kinds of
ontological commitment it displays, that is either left to the long run, or is shrugged
off as a pseudo-problem. This may sound familiar.
10 Ways Forward
The plethora of metaphysical theories and concepts that has come to prominence in
recent analytical metaphysics invites more than the standard piecemeal treatment of
problem after problem characteristic of earlier analytical philosophy. It invites
systematization, as practised by all the great metaphysicians. As reliance on predicate
logic and its semantics has diminished, it becomes more important to formulate anew
and set in connection with one another the system of categories which inform such a
metaphysics. The source, number, nature and justification of such categories remains
as controversial in metaphysics as it has always been, but one possible way forward in
the increasing diversity of metaphysical speculation may be to pay greater attention to
the systematic coherence of the system of categories used. An increasing number of
analytic metaphysicians are framing questions about the interconnections of their
theories via the system of categories deployed. That is just one possible way forward.
Through its development in analytic philosophy, metaphysics has arisen again
to the kind of prominence and variety that it enjoyed in medieval and early modern
23
Europe. Some of the problems it faces are new; many are old, and still unresolved.
The course that metaphysics will take in analytic philosophy is largely unclear: it is
even unsure whether its present prominence will continue. Perhaps the
metametaphysical imponderables will discourage philosophers from pursuing
metaphysics and their attention will turn elsewhere. But whether the present Golden
Age of metaphysics continues or fades, metaphysical problems will persist, and the
concepts and theories proposed by analytical philosophers in the recent phase will
take their deserved place in the history of the subject.
References
These are the works mentioned and alluded to in the essay, given in their most
definitive or accessible English-language editions.
Alexander, S. Space, Time and Deity. London: Macmillan, 1920.
Armstrong, D. M. Universals and Scientific Realism. Cambridge: Cambridge U. P.
1978.
—— A Combinatorial Theory of Possibility. Cambridge: Cambridge U. P., 1989.
—— A World of States of Affairs. Cambridge: Cambridge U. P., 1997.
—— Truth and Truthmakers. Cambridge: Cambridge U. P., 2004.
Anderson, J. Space, Time and the Categories. Lectures on Metaphysics, 1949–50.
Sydney: Sydney U. P., 2007.
Austin, J. L. Philosophical Papers. Oxford: Oxford U. P., 1970.
Ayer, A. J. Language, Truth and Logic. London: Gollancz, 1936. 2nd ed. 1946.
Ayer, A. J. et al. The Revolution in Philosophy. London: Macmillan, 1956.
Bergmann, G. The Metaphysics of Logical Positivism. Longmans, Green & Co., 1954.
2nd ed. Madison: University of Wisconsin Press, 1967.
—— Realism: A Critique of Brentano and Meinong. Madison: U. of Wisconsin P.,
1967.
Carnap, R. The Logical Construction of the World and Pseudoproblems in
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24
—— Meaning and Necessity. A Study in Semantics and Modal Logic. Chicago: U. of
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Collingwood, R. G. An Essay on Metaphysics. Oxford: Clarendon, 1940.
Frege, G. Collected Papers on Mathematics, Logic, and Philosophy. Oxford:
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Kim, J. Supervenience and Mind, Cambridge: Cambridge U. P., 1993.
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Lewis, D. K. On the Plurality of Worlds. Oxford: Blackwell, 1986.
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—— The Analysis of Sensations and the Relation of the Physical to the Psychical. La
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Passmore, J. A Hundred Years of Philosophy. Harmondsworth: Penguin, 2nd ed.
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—— Objective Knowledge: An Evolutionary Approach. Oxford: Clarendon, 1972.
Quine, W. V. From a Logical Point of View. Cambridge, Mass.: Harvard U. P. 1953.
—— Word and Object. Cambridge, Mass.: MIT Press, 1960.
—— Ontological Relativity and other Essays. New York: Columbia U. P., 1969.
Russell, B. The Principles of Mathematics. Cambridge: Cambridge U. P., 1903.
—— My Philosophical Development. London: Allen & Unwin, 1959.
—— The Philosophy of Logical Atomism and Other Papers, 1914–1919. Collected
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—— Foundations of Logic, 1903–1905. Collected Papers, Vol. 6, London:
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Ryle, G. The Concept of Mind. London: Hutchinson, 1949.
Simons, P. M. Parts. A Study in Ontology. Oxford: Clarendon, 1987.
Strawson, P. F. Individuals. An Essay in Descriptive Metaphysics. London: Methuen,
1959.
Tarski, A. Logic, Semantics, Metamathematics. Oxford: Clarendon, 1956. 2nd ed.
Indianapolis: Hackett, 1983.
van Inwagen, P. Material Beings. Ithaca: Cornell U. P., 1990.
Wolenski, J. Logic and Philosophy in the Lvov–Warsaw School. Dordrecht: Kluwer,
1989.
Whitehead, A. N. and Russell, B. Principia Mathematica. Cambridge: Cambridge U.
P., 1910–1913.
Williams, D. C. Principles of Empirical Realism. Springfield: Thomas, 1966.
Wittgenstein, L. Tractatus Logico-Philosophicus. London: Routledge and Kegan
Paul, 1963. First publ. in German 1921.
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