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{\title The Large-Scale Structure of Logical Empiricism: }{\author Greg Frost}{\operator Greg Frost}{\creatim\yr2004\mo2\dy28\hr17\min49}{\revtim\yr2004\mo10\dy16\hr19\min41}{\version9}{\edmins561}{\nofpages17}{\nofwords4732}{\nofchars26977}
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\f0 The Large Scale Structure of Logical Empiricism:
\par Unity of Science and the Elimination of Metaphysics
\par }\pard\plain \qc\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\lang1033\cgrid {\f0 
\par Greg Frost-Arnold}{\f2 
\par }\pard \widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {\f0 
\par }{\scaps\f0 Abstract:}{\f0 
  Two central and well-known philosophical goals of the logical empiricists are the unification of science and the elimination of metaphysics.  I argue, via textual analysis, that these two apparently distinct planks of the logical empiricist part
y platform are actually intimately related.  From the 1920\rquote 
s through 1950, one abiding criterion for judging whether an apparently declarative assertion or descriptive term is metaphysical is that that assertion or term cannot be incorporated into a langua
ge of unified science.  I explore various versions of this criterion throughout the works of Carnap and Neurath.
\par 
\par University of Pittsburgh
\par History and Philosophy of Science Department
\par ggfst@pitt.edu
\par 
\par 
\par }\pard \sl480\slmult1\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {\b\f0 1. Introduction
\par }\pard \fi720\sl480\slmult1\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {\f0 Two central planks of the logical empiricists\rquote 
 party platform are the unity of science thesis and their rejection of metaphysics.  To most current minds, these two topics likely appear }{\i\f0 prima facie}{\f0 
 rather different.   However, the central contention in this paper is that these two ideas are inti
mately intertwined in the writings of many logical empiricists. Close attention to the writings of central logical empiricists on the unity of science and the elimination of metaphysics reveals that, metaphorically speaking, these two goals are two sides 
of the same coin.  More prosaically, in different logical empiricists, from the 1920\rquote 
s through 1950, we find the following criterion (or an approximation thereof) at work for detecting metaphysics: an apparently meaningful, contentual utterance is metaphysical if and only if it cannot be incorporated into \lquote unified science\rquote  [
}{\i\f0 Einheitswissenschaft}{\f0 ].  In this essay, I will focus on Carnap and Neurath, for they wrote most extensively on both unity of science and the elimination of metaphysics, and their work is p
rominent among both their peers and modern scholars re-evaluating logical empiricism.
\par }\pard \sl480\slmult1\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {\f0 
\par }{\b\f0 2. Unity of Science}{ 
\par }\pard \fi720\sl480\slmult1\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {What did the logical empiricists mean by the phrase \lquote unity of science\rquote ? The fundamental fact to appreciate is that the unity of which the logical em
piricists speak is}{\i  not unity of laws or theories, but rather unity of language}{
.  This point has been increasingly stressed by scholars, e.g. (Creath 1996), so I will not attempt a complete substantiation of this claim.  Nonetheless, I devote this section t
o an abbreviated elaboration and defense of this exegetical contention.  First, to be explicit, Carnap, Neurath and others stress repeatedly that their thesis is }{\i not}{
 that the results of biology, psychology, sociology etc. can (or will) be ultimately derived from a single fundamental theory (presumably physics).  Rather, the logical empiricists\rquote  aim is to construct a }{\i language}{
 that can simultaneously express biological, psychological, social, and physical claims.  Carnap emphasizes that the reduction of (e.g.) biological laws to chemical or physical laws is an open question: \ldblquote there is at present no unity of laws
\u8230\'c9 On the other hand, there is a unity of language in science, viz., a common reduction basis for the terms of all branches of science\rdblquote  (1938, 61).  Neurath\rquote s views are similar.  He does not demand a unity of laws: \ldblquote 
Having a Universal Jargon [his term for his language of unified science] in common does not imply that the same scientific \lquote laws\rquote  have to be valid in the various fields of scientific research\rdblquote 
 (1946, 81).  Neurath, the social scientist, stresses the autonomy of sociological laws: \ldblquote Comprehensive sociological laws can be found without the need to be able\u8230\'c9 to build up these sociological laws from physical ones\rdblquote 
 (1983, 75).
\par Neurath is more antagoni
stic than Carnap to this unification of theories or laws.  Neurath claims this need to fit all knowledge into a single Procrustean bed constitutes a fundamental error of Cartesian and Leibnizean rationalism, and he stresses that the model for unified scie
nce is not a }{\i system}{, but an }{\i encyclopedia}{: the claims of an encyclopedia, unlike the claims of a system, are not all derivable from a few precise axioms.  For example, in the first article in the }{\i 
International Encyclopedia of Unified Science}{, Neurath (the }{\i Encyclopedia}{\rquote s editor-in-chief) writes: \ldblquote the great French Encyclopedia,\rdblquote  whose work the new }{\i Encyclopedia}{ continues, \ldblquote was not a \lquote }{\i 
faute de mieux}{ encyclopedia\rquote  in place of a comprehensive system, but an alternative to systems\rdblquote  (1938, 7; cf. 2, 16, 20).  This rejection of the single axiomatized system of knowledge in favor of a loosely connected encyclopedia is a }{
\i leitmotif }{running throughout Neurath\rquote s corpus.
\par What the logical empiricists\rquote  unified science requires is not a unity of laws, but something weaker: unity of }{\i language}{
.  We saw Carnap explicitly state this in his quote immediately above.  For Neurath as well, the crucial kind of unity is a unity of language: \ldblquote We can use the everyday language which we use when we talk about cows and calves throughout our emp
iricist discussions.  This was for me the main element of \lquote unity\rquote \rdblquote  (1983, 233).  Philipp Frank provides perhaps the simplest formulation of the unity of science thesis: \ldblquote there is one and the same language in all fields
\rdblquote  of science (1947, 165).  In }{\i Logical Syntax}{, Carnap offers the following more precise characterization of the thesis: every sub-language of science can be translated without loss into one language (1934/1937, 320).  
\par The next question to ask is: which language or languages fit this bill?  Many logical empiricists agree that the }{\i physicalist}{ language is one such.  In }{\i Logical Syntax}{
, Carnap states that the thesis of physicalism is precisely that the physicalist language can successfully perform this function of an overarching language for all of science (1934/1937, 320).}{\cs16\super  \chftn {\footnote \pard\plain 
\s15\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\lang1033\cgrid {\cs16\f0\fs22\super \chftn }{\f0\fs22  \ldblquote The thesis of }{\i\f0\fs22 physicalism}{\f0\fs22 
 maintains that the physical language is a universal language of science\emdash that is to say, that every language of any sub-domain of science can be equipollently translated into the physical language.  Fr
om this it follows that science is a unitary system within which there are no fundamentally diverse object-domains, and consequently no gulf, for example, between natural and social sciences  This is the thesis of the }{\i\f0\fs22 unity of science}{
\f0\fs22 .  \uc1\u8230\'c9 It is easy to see that both are theses of the syntax of the language of science.\rdblquote   (1934/1937, 320)}}}{
  Carnap defends this thesis most strongly in (1932/1934).  Neurath provides a detailed description of the physicalist language, which he also calls \lquote universal jargon.\rquote   It is }{\i not}{
 restricted to the vocabulary of physics.  Neurath describes his Universal Jargon as \ldblquote an everyday language that avoids certain phrases and is enriched by certain other phrases\rdblquote  (1983, 208); it \lquote avoids\rquote 
 metaphysical terms, and \lquote is enriched\rquote  by technical terms (1983, 91-92).  But the fact that the physicalist language can serve as the language for unified science does not imply that }{\i no}{ other languages could. 
\par Finally, the logical empiricist unity of science thesis is not refuted by Suppes\rquote  observation (
1978, 5) that the actual terminology used in various sub-disciplines of the sciences is increasingly divergent, with each subfield developing its own jargon.  Other scholars (e.g. Creath 1996) have already noted that Neurath\rquote s and Carnap\rquote 
s unity of science theses do not claim to provide a descriptive account of science as it is currently practiced.  In fact, Carnap explicitly agrees with Suppes\rquote  position in \u167\'a441 of the }{\i Aufbau}{.}{\cs16\super \chftn {\footnote 
\pard\plain \s15\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\lang1033\cgrid {\cs16\f0\fs22\super \chftn }{\f0\fs22  Carnap writes: \ldblquote as far as the logical }{\i\f0\fs22 meaning}{\f0\fs22 
 of its statements is concerned, science is concerned with only one domain. \uc1\u8230\'c9
 On the other hand, in its practical procedures, science does not always make use of this transformability [of statements into one domain] by actually transforming all its statements\rdblquote  (1928/1967, 70).}}}{
   Carnap, in his most extended defense of the unity of science thesis (1932/1934), argues only that the various languages of science }{\i could}{, in principle, be connected, not that they }{\i are}{ connected.  In sum, the logical positivists\rquote  un
ity of science thesis asserts that there exists a language in which all (scientific) knowledge can be couched, but not that this language is actually used, on a day-to-day basis, by scientists.    
\par }\pard \sl480\slmult1\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {
\par }{\b 3. The Elimination of Metaphysics
\par }{\tab }{\f0\cf1 
The logical empiricists are (in)famous for assuming an anti-metaphysical stance.  All the major figures in the group, as well as most of their patron saints, railed against metaphysics.  But how exactly did the logical empiricists purport to identify and 
excise the offending terms and claims, and thereby achieve their anti-metaphysical goal? This question becomes especially pressing if one agrees with Michael Friedman\rquote s assertion that \ldblquote 
metaphysical neutrality rather than radical empiricism... is... the essence of Carnap\rquote s position\rdblquote  (1999, 110).  Alan Richardson also puts this point strongly: \ldblquote if there is one defining feature of Carnap\rquote 
s philosophy, it is the claim that both science and philosophy can be done in a way that is neutral with respect to the traditional issues of metaphysics\rdblquote 
 (1992, 45).  Such claims need not be restricted to Carnap alone; metaphysical neutrality was a major, if not essential, goal for virtually all central logical positivists.  
\par }\pard \fi720\sl480\slmult1\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {How, then, do the logical empiricists expunge metaph
ysics from science?  The stereotypical view is that the logical empiricists eliminate metaphysics via a comprehensive application of the verificationist criterion of meaning.  (This view has been discounted somewhat in (Richardson 1992, 59) and, more indi
rectly, in (Creath 1982).)  As I hope to make clear, the verificationist criterion of meaning does play }{\i some}{ role in }{\i some}{ logical empiricist rejections of metaphysics\emdash 
however, its role is often a subsidiary one, and exclusive focus upon it leads to a fundamentally incomplete and therefore distorted image of the logical empiricists\rquote  attack on metaphysics.  A more complete picture of the logical empiricists
\rquote  anti-metaphysical project requires keeping their unity of science thesis in view.  Roughly put, one cri
terion separating meaningless metaphysics from cognitively significant science that holds over decades for many logical empiricists is the following:
\par }\pard \widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {(M)  An apparently declarative sentence or apparently descriptive term is }{\i metaphysical}{ if and only if that (purported) sentence or term }{\i 
cannot be incorporated into a total language of science}{. 
\par }\pard \sl480\slmult0\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {Furthermore, for the logical empiricists, failures of incorporation into unified science often come in two varieties: a metaphysical claim is either (i.) }{\i 
ungrammatical}{, or (ii.) grammatical, but }{\i isolated}{.  Case (ii.) arises when a grammatical sentence contains metaphysical terms. 
\par }\pard \fi720\sl480\slmult0\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {I must stress that (M) is an }{\i idealization}{.  No formulation of its brevity can accurately characterize the logical empiricists\rquote  views on metaph
ysics and unity of science, for the historical situation is fairly complex.  Different logical empiricists hold somewhat different views, and a single thinker\rquote s ideas about metaphysics often shift over time.  Furthermore, the }{\i bi}{conditiona}{
\i l}{ (M) usually does not appear in the texts as such.  Rather, a given logical empiricist virtually always uses only }{\i one}{
 direction of implication at a time, even though that thinker is committed to both directions, and might even use the other direction elsewhere in the very 
same work.   So, (M) should be understood as a slogan, from which actual formulations deviate to a greater or lesser degree.  
\par The next task, then, is to present a more complete and detailed account of the logical empiricists\rquote  rejection of metaphysics across several texts.  By examining the several \lquote variants\rquote 
 of (M), we can determine to what extent (M) captures a basic element of logical empiricist thought, and also what complex, historical nuances (M) elides.  In what follows, I focus on Carnap, for he, mo
re than any other logical empiricist, works out a detailed position on both the unity of science and the rejection of metaphysics.  I then show that Neurath\rquote 
s texts support attributing (M) to him as well, though his expression of the rejection of metaphysics lacks the fine-grained particulars of Carnap\rquote s. 
\par Let us begin with Carnap\rquote s treatment of metaphysics in the }{\i Aufbau}{.  How does Carnap there identify metaphysics?  Carnap discusses the concepts of essence, reality, and the mind-body connection (among othe
rs), and concludes that each, if taken in their customary sense, is metaphysical.  Each of these purported concepts is deemed metaphysical on the grounds that it cannot be incorporated into any \lquote construction system\rquote  [}{\i Konstitutionsystem}
{] of the sorts Carnap describes in the }{\i Aufbau}{.  We can phrase Carnap\rquote s criterion for metaphysics in the }{\i Aufbau}{ as follows:
\par }\pard \widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {
\par (M}{\sub Aufbau}{) An apparent sentence is metaphysical if and only if it contains concepts that cannot be constructed in a constructional system.
\par }\pard \sl480\slmult0\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {This connection between non-constructability and metaphysics is clear in Carnap\rquote s treatment of the metaphysical \lquote problem of reality\rquote :
\par }\pard \widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {
\par The concept of reality (in the sense of independence from cognizing consciousness) does not belong within (rational) science, but within
 metaphysics.  This is now to be demonstrated.  For this purpose, we investigate whether this concept can be constructed, i.e., whether it can be expressed through objects of the most important types which we have already considered, namely, the autopsych
ological, the physical, the heteropsychological, and the cultural. (1928/1963, 282)
\par 
\par }\pard \sl480\slmult1\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {To show that a concept is metaphysical, it must be shown that that concept cannot be constructed from }{\i any}{ basic objects\emdash not just phenomenal, \lquote 
autopsychological\rquote  one Carnap develops most fully in the }{\i Aufbau}{.  The mind-body problem (in Carnap\rquote s terms, the \lquote parallelism\rquote  between mental states and brain states) is similarly unconstructable:
\par }\pard \widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {The question for an }{\i explanation of these findings}{ [that mental states and brain states can be placed in a one-to-one correspondence] }{\i lies outside the range of science}{
; this already shows itself in the fact that this question cannot be expressed in concepts that can be constructed;\u8230\'c9 (This holds for any such constructional system and not only for
 a constructional system of our specific kind.) Rather, the quest for an explanation of that parallelism belongs within metaphysics.  (Carnap 1928/1967, 270-1)
\par  
\par }\pard \sl480\slmult1\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {The above parenthetical remark shows clearly that, for Carnap, constructability is a more fund
amental criterion than verifiability in determining whether a concept or claim is metaphysical, for presumably the \lquote specific kind\rquote 
 to which Carnap refers is the constructional system with autopsychological basis.  Other metaphysical concepts are shown to h
ave the same property; none can be incorporated into a constructional system.  This non-conceptual nature of metaphysics is directly connected to the logical empiricists\rquote  well-known rejection of }{\i intuition}{. Carnap writes: \ldblquote 
metaphysics does not wish to grasp its object by proceeding via concepts\u8230\'c9 but immediately through intuition\rdblquote 
 (1928/1967, 295), which is ineffable.  The ineffability of so-called metaphysical knowledge was stressed by Schlick (1926).  There are two significant differences between (M}{\sub Aufbau}{) and (M): first, in the }{\i Aufbau}{
, Carnap thinks primarily in terms of concepts; sentences are secondary.  Second, the }{\i Aufbau}{ lacks the claim that many sentences of metaphysics are ungrammatical.  This idea, drawn from Wittgenstein\rquote s }{\i Tractatus}{, does not come i
nto prominence in Carnap\rquote s writings until after the }{\i Wienerkreis}{ reads the }{\i Tractatus}{ intensively together. 
\par }\pard \fi720\sl480\slmult1\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {Carnap\rquote s most focused attack on metaphysics is \ldblquote Overcoming Metaphysics through the Logical Analysis of Language\rdblquote 
 (1932/1959).  Here Carnap clearly draws the distinction, described above, between the two kinds of pseudo-sentences that cannot be incorporated into the language of science: (i.) ungrammatical strings of symbols, and (ii.) grammatical \lquote sentences
\rquote  whose terms cannot be connected to the meaningful terms and sentences of the language.  I shall deal with each in turn.  }{\f0\cf1 Carnap begins \ldblquote Overcoming Metaphysics\rdblquote 
 by noting that there have been several attempts throughout the centuries to abolish metaphysics from the intellectual landscape.  However, \ldblquote only\rdblquote  with the \ldblquote development of modern logic\rdblquote  can \ldblquote 
the decisive step be taken\rdblquote  in this pursuit (1932/1959, 61).  Why?  A sentence (even if it contains only meaningful words) is meaningless, i.e. metaphysical, if it cannot be expressed in a predicate calculus such as }{\i\f0\cf1 
Principia Mathematica}{\f0\cf1 .  This is why the \lquote development of modern logic\rquote  is so important to the elimination of metaphysics: we pick out metaphysical sentences by finding the strings of symbols which }{\i\f0\cf1 appear}{\f0\cf1 
 meaningful, but cannot be expressed in the logical language of the }{\i\f0\cf1 Principia Mathematica}{\f0\cf1 .}{\cs16\f0\cf1\super \chftn {\footnote \pard\plain \s15\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\lang1033\cgrid {
\cs16\f0\fs22\super \chftn }{\f0\fs22  Alan Richardson has stressed this idea: \ldblquote The universal applicability and expressive power of the new logic does all the serious work in the rejection of metaphysics\rdblquote  (Richardson 1998, 26-27).  }}}
{\f0\cf1   This conception of metaphysics is fundamentally Tractarian: whatever cannot be expressed grammatically in the ideal symbolic language of the }{\i\f0\cf1 Tractatus}{\f0\cf1 
 is meaningless metaphysics.  Carnap and Neurath explicitly state that their view on the elimination of metaphysics in the early 1930\rquote s \ldblquote }{was in essentials that of Wittgenstein\rdblquote 
 (Carnap 1934/1937, 322; see also Neurath 1983, 54)}{\f0\cf1 .
\par So much for Carnap\rquote s account of metaphysical sentences; when is a }{\i\f0\cf1 term}{\f0\cf1  metaphysical, i.e., meaningless?  Carnap takes us on a brief
 detour through sentences, for a term is shown to be meaningless by showing that atomic sentences containing that term are meaningless.  He asserts that the question \ldblquote What is the meaning of [an atomic sentence] S?\rdblquote 
 is equivalent to each of the following two questions:
\par }\pard \widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {\f0\cf1 (1.) What sentences is S }{\i\f0\cf1 deducible}{\f0\cf1  from, and what sentences are deducible from S?
\par (2.) Under what conditions is S supposed to be true, and under what conditions false?
\par }\pard \fi720\li720\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin720\itap0 {\f0\cf1 (1932/1959, 62) 
\par }\pard \sl480\slmult0\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {\f0\cf1 Here again, we see a version of (M).  Here, a sentence (and thereby its constituents) is shown to be meaningful by placing it within a larger \lquote 
inferential network\rquote }{\cs16\f0\cf1\super \chftn {\footnote \pard\plain \s15\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\lang1033\cgrid {\cs16\f0\fs22\super \chftn }{\f0\fs22  Excluding purely logical implications: \lquote 
God exists\rquote  entails \lquote God exists or water boils at 100 degrees Centigrade,\rquote  and is entailed by \lquote God exists and mammals have hair.\rquote }}}{\f0\cf1 
 ((1.) captures the syntactic aspect of the network, (2.) the semantic).  Grammatical strings that cannot be so placed, Carnap maintains, contain metaphysical terms.  This is very similar to the unconstructable concepts of the }{\i\f0\cf1 Aufbau}{\f0\cf1 
.  But, one may wonder, what guarantees that }{\i\f0\cf1 any}{\f0\cf1  sentences in the larger inferential network are meaningful?\emdash Couldn\rquote t we construct a network of nonsense words? 
\par }\pard \fi720\sl480\slmult0\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {\f0\cf1 Here is where }{\i\f0\cf1 verificationism}{\f0\cf1  rears its head.  Carnap states that \lquote What is the meaning of S?\rquote 
, and hence questions (1.) and (2.) above, are also equivalent to \ldblquote (3.) How is S to be }{\i\f0\cf1 verified}{\f0\cf1 ?\rdblquote  (}{\i\f0\cf1 ibid.}{\f0\cf1 
).  For Carnap in 1932, this question is answered by specifying the deducibility relations between S and the \ldblquote  \lquote observation sentences\rquote  or \lquote protocol sentences.\rquote 
 It is through this reduction that the word acquires its meaning\rdblquote  (1932/1959, 63).  However, the specific nature of the protocol sentences is, for Carnap, irrelevant to the elimination of metaphysics: \ldblquote 
For our purposes we may ignore entirely the question concerning the content and form of the primary sentences (protocol sentences)\rdblquote : they could deal with \ldblquote the simplest qualities of sense\rdblquote  (Mach), \ldblquote 
total experience and similarities between them\rdblquote  (the }{\i\f0\cf1 Aufbau}{\f0\cf1 ), or simply \ldblquote things\rdblquote  (}{\i\f0\cf1 ibid.}{\f0\cf1 
).  Furthermore, two years later, Carnap states that which sentences are protocol sentences is a matter of decision (1934/1987).
\par Carnap\rquote s basic idea, I take it, is that there are some sentences\emdash the \lquote primary\rquote  or \lquote protocol\rquote  sentences\emdash 
whose meaningfulness is uncontroversial, assumed, or somehow otherwise guaranteed.  For Carnap has just said that an arbitrary sentence S, and hence the terms it contains, are shown to be meaningful by showing that S is non-trivially inferentia
lly related to some }{\i\f0\cf1 other}{\f0\cf1  set of sentences.  Carnap must be assuming that this other set of sentences is meaningful, and that its meaningfulness \lquote filters down,\rquote 
 via implications, to the given sentence S.  We could call this doctrine \lquote semantic foundationalism\rquote : just as an epistemic foundationalist holds that there are \lquote unjustified justifiers\rquote 
 which function as the ultimate source for all claims\rquote  justification, a semantic foundationalist holds that some set of sentences functions as the ultimate source for all sentences\rquote 
 meaning, though their own meaningfulness lacks any further justification from other vocabulary (though they may be justified by practice).  
\par Carnap\rquote s characterization of the metaphysical does not remain completely static.  In 1934, }{\i\f0\cf1 Logical Syntax of Language}{\f0\cf1 
 appears, and with it a slightly modified program for eliminating metaphysics.  We find the same basic ideas as in \ldblquote Overcoming Metaphysics,\rdblquote  but with an added wrinkle: the principle of tolerance. 
\par }\pard \widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {
\par The view here presented [in accordance with
 the principle of tolerance] allows great freedom in the introduction of new primitive concepts and new primitive sentences in the language of physics or the language of science in general; yet at the same time it retains the }{\i 
possibility of differentiating pseudo-concepts and pseudo-sentences}{ from real scientific concepts and sentences, }{\i and thus of eliminating the former}{
.  [This elimination, however, is not so simple as it appeared to be on the basis of the earlier position of the Vienna Circle\u8230\'c9 On that view it was a question of \ldblquote }{\i the}{ language\rdblquote 
 in an absolute sense; it was thought possible to reject both concepts and sentences if they did not fit into }{\i the}{ language.] (1934/1937, 322)}{\f0\cf1 
\par }\pard\plain \s17\sl480\slmult0\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\cf1\lang1033\cgrid {That is, we can still avoid metaphysical pseudo-concepts and pseudo-sentences
, even if we adopt the Principle of Tolerance and thereby reject the notion that there is a single \lquote correct\rquote  language.  As in \ldblquote Overcoming Metaphysics,\rdblquote  the \lquote sentences\rquote 
 that are ungrammatical, and those apparently descriptive sentences that cannot be connected with the language of empirical science are dismissed as pseudo-sentences, as metaphysics (}{\i ibid}{
.).  This is essentially no different from the view advocated two years previous.
\par }\pard\plain \fi720\sl480\slmult0\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\lang1033\cgrid {\f0\cf1 Thus Carnap allows in }{\i\f0\cf1 Logical Syntax}{\f0\cf1  that there can be }{\i\f0\cf1 many}{\f0\cf1  languages of sci
ence, but that metaphysical pseudo-sentences can nonetheless be eliminated.  Furthermore, these languages can be fundamentally different from one another, in the sense that they cannot be intertranslated into one another without loss of content.  Two lang
uages will be fundamentally different in this sense whenever one is weaker than another.  For a Carnapian example, consider Languages I and II of }{\i\f0\cf1 Logical Syntax}{\f0\cf1 : Language I, intended to capture formally the mathematical intuitionist
\rquote s viewpoint, is weaker t
han Language II, which is expressively rich enough to capture all of classical analysis.  Thus, there are sentences that are grammatical in II, but in I are ungrammatical, and hence metaphysical.  (For example, a sentence about \lquote 
unconstructable numbers\rquote  wo
uld count as legitimate in II but would be a metaphysical pseudo-sentence in I.) Similarly, first-order logic is essentially weaker than higher-order logic, so certain sentences condoned in second-order logic would be metaphysical in first-order logic.  W
e are led to a relativity of metaphysics to languages, codified as follows:
\par }\pard \widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {\f0\cf1 
\par (M}{\f0\cf1\sub LSL}{\f0\cf1 ):}{  An apparently declarative sentence or apparently descriptive term is }{\i metaphysical with respect to language L }{if and only if that (purported) sentence or term }{\i cannot be incorporated into L.}{\f0\cf1 
\par }\pard \sl480\slmult0\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {\f0\cf1 where \lquote incorporation\rquote  is understood as before. 
\par }\pard \fi720\sl480\slmult0\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {\f0\cf1 Does Carnap\rquote 
s indexing of metaphysics to a particular language threaten my thesis that, for the logical empiricists, metaphysics is to be identified with those propositions that cannot be in
corporated into a unified language of science?  I do not think so; rather, my account needs two additional elements of sophistication.  First, the full formulation of the thesis needs to be expanded so that it takes into account the \lquote 
language relativity\rquote  endorsed in }{\i\f0\cf1 Logical Syntax}{\f0\cf1 : }{\i\f0\cf1 p}{\f0\cf1  is metaphysical }{\i\f0\cf1 with respect to a unified language of science}{\f0\cf1  iff }{\i\f0\cf1 p}{\f0\cf1 
 cannot be incorporated into a unified language of science.  Second, I conjecture that the }{\i\f0\cf1 usual}{\f0\cf1  or }{\i\f0\cf1 standard}{\f0\cf1  extension of the term \lquote metaphysics\rquote  }{\i\f0\cf1 simpliciter}{\f0\cf1 
 (i.e., without the index to a language), is probably well captured by taking the arbitrary language L in (M}{\f0\cf1\sub LSL}{\f0\cf1 ) to be a unified language of science.  
\par Lastly, perhaps this relativization of metaphysics to languages reveals something insightful about the way the term \lquote metaphysics\rquote  is used.  Intuitionists }{\i\f0\cf1 do}{\f0\cf1 
 find something suspect about the unconstructable numbers of classical mathematics, and some would be inclined to call claims about such entities \lquote metaphysics.\rquote   Heyting, expressing the intuitionist viewpoint, writes: \ldblquote If \lquote 
to exist\rquote  does not mean \lquote to be constructed,\rquote  it must have some metaphysical meaning\rdblquote  (1971/1983, 67).  Similarly, philosophers who find second-order logic suspicious call its quantification over predicates \lquote Platonism,
\rquote  after the grandfather of all metaphysicians.  And if we think of metaphysics as }{\i\f0\cf1 nonsense}{\f0\cf1 , as the Vienna Circle and Wittgenstein do, then it becomes clearer that the label of \lquote metaphysical\rquote 
 should be indexed to a particular language\emdash for what is meaningful in one language simply will not be in another.  
\par }\pard \sl480\slmult0\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {\f0\cf1 \tab In 1950\rquote s \ldblquote Empiricism, Semantics, and Ontology,\rdblquote  Carnap\rquote 
s basic idea for identifying metaphysics is essentially the same.  However, the terminology has shifted: instead of speaking of constructional systems or languages, Carn
ap now speaks of linguistic frameworks.  But here again, a claim is shown to be non-metaphysical by incorporating it into a (pragmatically) acceptable linguistic framework.
\par }\pard \widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {
\par [T]he concept of reality\u8230\'c9in internal questions is\u8230\'c9 [a] scientific, }{\i non-metaphysical}{ concept.  To recognize something as a real thing or event means to }{\i succeed in incorporating it into the system of things\u8230\'c9
, according to the rules of the framework}{. \u8230\'c9 (1950/1956, 207; my italics) 
\par 
\par }\pard \sl480\slmult1\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {The importance of a shared scientific language for identi
fying metaphysics also recurs here.  It is on precisely these grounds that Carnap criticizes philosophers who ask the \lquote external\rquote  question \ldblquote Are there numbers?\rdblquote :
\par }\pard \widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {Unfortunately, these philosophers have not given a formulations of their question in the common scientific language.  Therefore\u8230\'c9
 they have not succeeded in giving the external question cognitive content. (1950/1956, 209)
\par 
\par }\pard \sl480\slmult1\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {And questions without \lquote cognitive content\rquote  are metaphysical.  Thus, Carnap\rquote s attitude towards metaphysics in 1950 is very closely r
elated to his view in the twenties; linguistic frameworks replace construction systems, but the basic strategy for identifying and eliminating metaphysics remains the same.
\par }\pard\plain \s15\sl480\slmult1\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\lang1033\cgrid {\tab So much for Carnap\rquote s views on metaphysics; what of Neurath?  Though he eschews Carnap\rquote 
s formal, precise languages in favor of his \lquote universal jargon\rquote 
 based on everyday language, he shares the fundamental idea found in Carnap: an apparently meaningful sentence or term is metaphysical if and only if it cannot be incorporated into unified science.  First, the \lquote only if\rquote  direction:}{
\cs16\super \chftn {\footnote \pard\plain \s15\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\lang1033\cgrid {\cs16\f0\fs22\super \chftn }{\f0\fs22  See also (1983, 54, 57, 61, 73, 173). Neurath sometimes speaks of \lquote physicalism
\rquote  instead of \lquote unified science,\rquote  but, for Neurath, \ldblquote physicalism is the form work in unified science takes in our time\rdblquote  (1983, 56).}}}{
\par }\pard\plain \widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\lang1033\cgrid {If it [a proposed scientific sentence] is\u8230\'c9 meaningless\emdash i.e., metaphysical \emdash 
then of course it falls outside the sphere of unified science. (1983, 58)
\par 
\par And the \lquote if\rquote  direction:
\par 
\par statements that through their structure or special grammar could not be placed within the language of the encyclopedia\emdash in general \lquote isolated\rquote  statements, \u8230\'c9 are statements \lquote without meaning in a certain language\rquote 
.  For these statements the Vienna Circle has often used the term \lquote metaphysical statements\rquote . (1983, 161)
\par 
\par }\pard \sl480\slmult1\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {Note that Neurath mentions the strictures against both ungrammatical and isolated \lquote sentences.\rquote 
  Where Carnap employs a constitution system or a linguistic framework, Neurath uses an encyclopedic language based on everyday communication instead; but otherwise, their views are very close.
\par }\pard \fi720\sl480\slmult1\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {\f0\cf1 Recall the notion of \lquote semantic foundationalism,\rquote  mentioned above: a sentence\rquote 
s meaningfulness is demonstrated by showing that that sentence is connected via consequence-relations to sentences whose meaningfulness is given antecedently.  The question Carnap was undecided on in 1932 was \lquote 
Which sentences are given as meaningful?\rquote   Neurath\rquote s version of unified science presents us with another way to answer this question.  Neurath repeatedly states that unified science should begin from everyday langua
ge, with minor corrections.  Why?  One possible reason is that everyday language is meaningful if any language is; everyday language would be the most indisputable case of a meaningful language.  We are more committed to the meaningfulness of everyday lan
guage than any other.  Thus, if we have to pick a \lquote semantic foundation,\rquote 
 everyday language seems the best we can do.  (There are other reasons Neurath starts with everyday language: he values the democratization and popularization of scientific knowledge, a
nd he is suspicious of any framework that aims to break loose of our present historical situation.) 
\par }{One might criticize my interpretation of Neurath\rquote s claims about the unity of science as follows: a central aim of work in unified science is demolition of 
the barriers between the scientific study of nature and of the mind; my interpretation misses that aspect entirely.  I concede, of course, that Neurath repeatedly and unequivocally urged the value of breaking down disciplinary barriers.  But, interestingl
y, Neurath claims that the motivation underlying the separation of the sciences is }{\i metaphysical}{.  When his program is realized,
\par }\pard \widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {each basic decomposition of unified science is eliminated\u8230\'c9, for example, that into \lquote natural sciences\rquote  and \lquote mental sciences\rquote \u8230\'c9 .  T
he tenets with which we want to justify the division are\u8230\'c9 always of a metaphysical kind, that is, meaningless. (1983, 68)}{\cs16\super \chftn {\footnote \pard\plain \s15\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 
\f4\lang1033\cgrid {\cs16\f0\fs22\super \chftn }{\f0\fs22  See also (1983, 44, 50, 69).}}}{
\par }\pard \sl480\slmult0\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {So, according to Neurath, any assertion used to justify a strict division of the sciences is metaphysi
cal.  If the various sciences were unified, then any such assertion would be ruled out.  Thus, unified science, which shows disciplinary barriers are not insuperable, eliminates a certain kind of metaphysics\emdash 
specifically, it eliminates any theory that purports to deal with \ldblquote a special sphere of the \lquote soul\rquote \rdblquote 
 (1983, 73), distinct from the remainder of the spatiotemporal world.  Unification of the sciences may be valuable for its own sake, but it also serves to eliminate metaphysics. 
\par \tab 
\par }{\b\f0\cf1 4. Conclusion
\par }\pard\plain \s17\sl480\slmult0\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\cf1\lang1033\cgrid {\f0 \tab Thus far, 
I have argued that, in the writings of central logical empiricists, there is a close conceptual connection between the unity of science thesis and the elimination of metaphysics, and that this connection is captured, to a first approximation, by (M).  In 
closing, I present one piece of evidence that this connection is not merely conceptual, but also }{\i\f0 genealogical}{\f0 .  That is, the term \lquote unified science\rquote  [}{\i\f0 Einheitswissenschaft}{\f0 
], suggested by Neurath, sprung directly out of the Vienna Circle\rquote s elimination of metaphysics.  Neurath, recalling the Circle\rquote s discussion of the }{\i\f0 Tractatus}{\f0 , explains how he came to introduce the term. }{
\par }\pard \s17\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 {
\par Eliminating \lquote meaningless\rquote  sentences became a kind of game\u8230\'c9 But I very soon felt uneasy, when members of our Vienna Circle suggested that we should drop the term \lquote philosophy\rquote  as a name for a set of sentences \u8230\'c9
 but use it as a name for the activity engaged in improving given sentences by \lquote demetaphysicalizing\rquote  them  \u8230\'c9 Thus I came to suggest as our object, the collection of material, which we coul
d accept within the framework of scientific language; for this I thought the not-much-used term \lquote Unified Science\rquote  (}{\i Einheitswissenschaft}{\u8230\'c9) a suitable one. (1983, 231)
\par }\pard\plain \sl480\slmult0\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\lang1033\cgrid {\f0\cf1 Thus, the very term \lquote unified science\rquote  arose directly from a desire to re-name the anti-metaphysical goal of the }{\i\f0\cf1 
Wienerkreis}{\f0\cf1 .  
\par 
\par }{\b\f0\cf1 
\par }\pard\plain \s1\keepn\widctlpar\aspalpha\aspnum\faauto\outlinelevel0\adjustright\rin0\lin0\itap0 \b\f4\lang1033\cgrid {Bibliography
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\par }\pard\plain \widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\lang1033\cgrid {\f0\cf1 
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\par 
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\par 
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\par 
\par }\pard\plain \s17\widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\cf1\lang1033\cgrid {\f0 Neurath, Otto (1938).  \ldblquote Unified Science as Encyclopedic Integration,\rdblquote  in }{\i\f0 International Encyclopedia of Unified Science}{
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\par }\pard\plain \widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\lang1033\cgrid {\f0\cf1 
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\par 
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\par }\pard\plain \widctlpar\aspalpha\aspnum\faauto\adjustright\rin0\lin0\itap0 \f4\lang1033\cgrid {\f0\cf1 
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\par }}