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Ramsey sentences are formal logical reconstructions of theoretical
proposition In logic and linguistics, a proposition is the meaning of a declarative sentence. In philosophy, "meaning" is understood to be a non-linguistic entity which is shared by all sentences with the same meaning. Equivalently, a proposition is the no ...
s attempting to draw a line between science and metaphysics. A Ramsey sentence aims at rendering propositions containing non-observable theoretical terms (terms employed by a theoretical language) clear by substituting them with observational terms (terms employed by an observation language, also called empirical language). Ramsey sentences were introduced by the logical empiricist philosopher
Rudolf Carnap Rudolf Carnap (; ; 18 May 1891 – 14 September 1970) was a German-language philosopher who was active in Europe before 1935 and in the United States thereafter. He was a major member of the Vienna Circle and an advocate of logical positivism. ...
. However, they should not be confused with Carnap sentences, which are neutral on whether there exists anything to which the term applies.


Distinction between scientific (real) questions and metaphysical (pseudo-)questions

For Carnap, questions such as “Are
electron The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary partic ...
s real?” and “Can you prove electrons are real?” were not legitimate questions, nor did they contain any great philosophical or
metaphysical Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of consci ...
truths. Rather, they were meaningless "pseudo-questions without cognitive content,” asked from outside a language framework of science. Inside this framework, entities such as electrons or sound waves, and relations such as
mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different element ...
and
force In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a ...
not only exist and have meaning but are "useful" to the scientists who work with them. To accommodate such internal questions in a way that would justify their theoretical content empirically – and to do so while maintaining a distinction between analytic and
synthetic Synthetic things are composed of multiple parts, often with the implication that they are artificial. In particular, 'synthetic' may refer to: Science * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic o ...
propositions – Carnap set out to develop a systematized way to consolidate theory and empirical observation in a meaningful language formula.


Distinction between observable and non-observable

Carnap began by differentiating observable things from non-observable things. Immediately, a problem arises: neither the
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nor the
English language English is a West Germanic language of the Indo-European language family, with its earliest forms spoken by the inhabitants of early medieval England. It is named after the Angles, one of the ancient Germanic peoples that migrated to t ...
naturally distinguish predicate terms on the basis of an observational categorization. As Carnap admitted, "The line separating observable from non-observable is highly arbitrary." For example, the predicate "hot" can be perceived by touching a hand to a lighted coal. But "hot" might take place at such a microlevel (e.g., the theoretical "heat" generated by the production of proteins in a
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cell) that it is virtually non-observable (at present). Physicist-philosopher
Moritz Schlick Friedrich Albert Moritz Schlick (; ; 14 April 1882 – 22 June 1936) was a German philosopher, physicist, and the founding father of logical positivism and the Vienna Circle. Early life and works Schlick was born in Berlin to a wealthy Prussian ...
characterized the difference linguistically, as the difference between the German verbs "kennen" (knowing as being acquainted with a thing – perception) and "erkennen" (knowing as understanding a thing – even if non-observable). This linguistic distinction may explain Carnap's decision to divide the vocabulary into two artificial categories: a vocabulary of non-observable ("theoretical") terms (hereafter "VT"): i.e., terms we know of but are not acquainted with (erkennen), and a vocabulary of observable terms ("VO"), those terms we are acquainted with (kennen) and will accept arbitrarily. Accordingly, the terms thus distinguished were incorporated into comparable sentence structures: T-terms into theoretical sentences (T-sentences); O-terms into observational sentences (O-sentences). The next step for Carnap was to connect these separate concepts by what he calls "correspondence rules" (C-rules), which are "mixed" sentences containing both T- and O-terms. Such a theory can be formulated as: T + C = df: the conjunction of T-postulates + the conjunction of C-rules – i.e., T_1 \land T_2 \land \cdots \land T_n ) + ( C_1 \land C_2 \land \cdots \land C_m )/math>. This can be further expanded to include class terms such as for the class of all molecules, relations such as "betweenness," and predicates: e.g., TC ( t1, t2, . . ., tn, o1, o2, . . ., om). Though this enabled Carnap to establish what it means for a theory to be "empirical," this sentence neither defines the T-terms explicitly nor draws any distinction between its analytic and its synthetic content, therefore it was not yet sufficient for Carnap's purposes. In the theories of Frank P. Ramsey, Carnap found the method he needed to take the next step, which was to substitute variables for each T-term, then to quantify existentially all T-terms in both T-sentences and C-rules. The resulting "Ramsey sentence" effectively eliminated the T-terms as such, while still providing an account of the theory's empirical content. The evolution of the formula proceeds thus: :Step 1 (empirical theory, assumed true): TC ( t1 . . . tn, o1 . . . om) :Step 2 (substitution of variables for T-terms): TC (x1 . . . xn, o1 . . . om) :Step 3 (\exists-quantification of the variables): \exists x_1 \ldots \exists x_n TC ( x_1 \ldots x_n, o_1 \ldots o_m). Step 3 is the complete Ramsey sentence, expressed "RTC," and to be read: "There are some (unspecified) relations such that TC (''x''1 . . . ''x''''n'', ''o''1 . . . ''o''''m'') is satisfied when the variables are assigned these relations. (This is equivalent to an interpretation as an appropriate model: there are relations ''r''1 . . . ''r''''n'' such that TC (''x''1 . . . ''x''''n'', ''o''1 . . . ''o''''m'') is satisfied when xi is assigned the value ri, and 1 \leq i \leq m.) In this form, the Ramsey sentence captures the factual content of the theory. Though Ramsey believed this formulation was adequate to the needs of science, Carnap disagreed, with regard to a comprehensive reconstruction. In order to delineate a distinction between analytic and synthetic content, Carnap thought the reconstructed sentence would have to satisfy three desired requirements: # The factual (FT) component must be observationally equivalent to the original theory (TC). # The analytic (AT) component must be observationally uninformative. # The combination of FT and AT must be
logically equivalent Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premises ...
to the original theory – that is, F_T + A_T \Leftrightarrow TC. Requirement 1 is satisfied by RTC in that the existential quantification of the T-terms does not change the
logical truth Logical truth is one of the most fundamental concepts in logic. Broadly speaking, a logical truth is a statement which is true regardless of the truth or falsity of its constituent propositions. In other words, a logical truth is a statement whi ...
(L-truth) of either statement, and the reconstruction FT has the same O-sentences as the theory itself, hence RTC is observationally equivalent to TC : (i.e., for every O-sentence: O, C \models O \Leftrightarrow ^TC \models O/math> ). As stated, however, requirements 2 and 3 remain unsatisfied. That is, taken individually, AT does contain observational information (such-and-such a theoretical entity is observed to do such-and-such, or hold such-and-such a relation); and AT does not necessarily follow from FT. Carnap's solution is to make the two statements conditional. If there are some relations such that C (x1 . . . xn, o1 . . . om)is satisfied when the variables are assigned some relations, then the relations assigned to those variables by the original theory will satisfy C (t1 . . . tn, o1 . . . om)– or: RTC → TC. This important move satisfies both remaining requirements and effectively creates a distinction between the total formula's analytic and synthetic components. Specifically, for requirement 2: The conditional sentence does not make any information claim about the O-sentences in TC, it states only that "if" the variables in are satisfied by the relations, "then" the O-sentences will be true. This means that every O-sentence in TC that is logically implied by the sentence RTC → TC is L-true (i.e., every O-sentence in AT is true or not-true: the metal expands or it does not; the chemical turns blue or it does not, etc.). Thus TC can be taken as the non-informative (i.e., non-factual) component of the statement, or AT. Requirement 3 is satisfied by inference: given AT, infer FT → AT. This makes AT + FT nothing more than a reformulation of the original theory, hence AT Ù FT ó TC. Carnap took as a fundamental requirement a respect for the
analytic–synthetic distinction The analytic–synthetic distinction is a semantic distinction, used primarily in philosophy to distinguish between propositions (in particular, statements that are affirmative subject– predicate judgments) that are of two types: analytic propo ...
. This is met by using two distinct processes in the formulation: drawing an empirical connection between the statement's factual content and the original theory (observational equivalence), and by requiring the analytic content to be observationally non-informative.


Application

Carnap's reconstruction as it is given here is not intended to be a literal method for formulating scientific propositions. To capture what
Pierre Duhem Pierre Maurice Marie Duhem (; 9 June 1861 – 14 September 1916) was a French theoretical physicist who worked on thermodynamics, hydrodynamics, and the theory of elasticity. Duhem was also a historian of science, noted for his work on the Euro ...
would call the entire "holistic" universe relating to any specified theory would require long and complicated renderings of RTC → TC. Instead, it is to be taken as demonstrating logically that there is a way that science could formulate empirical, observational explications of theoretical concepts – and in that context the Ramsey and Carnap construct can be said to provide a formal justificatory distinction between scientific observation and metaphysical inquiry.


Criticism

Among critics of the Ramsey formalism are John Winnie, who extended the requirements to include an "observationally non-creative" restriction on Carnap's AT – and both W. V. O. Quine and
Carl Hempel Carl Gustav "Peter" Hempel (January 8, 1905 – November 9, 1997) was a German writer, philosopher, logician, and epistemologist. He was a major figure in logical empiricism, a 20th-century movement in the philosophy of science. He is esp ...
attacked Carnap's initial assumptions by emphasizing the ambiguity that persists between observable and non-observable terms.


See also

* Ramsey-style epistemic structural realism


Notes


Works cited

*Carnap, R. (1950) "Empiricism, Semantics, and Ontology," in Paul Moser and Arnold Nat, ''Human Knowledge'' Oxford University Press. (2003). *Carnap, R. (1966) ''An Introduction to the Philosophy of Science'' (esp. Parts III, and V), ed. Martin Gardner. Dover Publications, New York. 1995. *Carnap, R. (2000) riginally: 29 December 1959"Theoretical Concepts in Science," with introduction by Stathis Psillos. ''Studies in History and Philosophy of Science'' 31(1). *Demopoulos, W. "Carnap on the Reconstruction of Scientific Theories," ''The Cambridge Companion to Carnap'', eds. R. Creath and M. Friedman. *Moser, P. K. and vander Nat, A. (2003) ''Human Knowledge'' Oxford Univ. Press. *Schlick, Moritz (1918) ''General Theory of Knowledge'' (Allegemeine Erkenntnislehre). Trans. Albert Blumberg. Open Court Publishing, Chicago/La Salle, IL. (2002). *Hallvard Lillehammer, D. H. Mellor (2005)
Ramsey's legacy
Oxford University Press, p. 109. *Stathis Psillos
"Carnap, the Ramsey-Sentence and Realistic Empiricism"
2000.


External links


"Epistemic Structural Realism and Ramsey Sentences""Theoretical Terms in Science"
{{DEFAULTSORT:Ramsey sentences Philosophy of science Sentences by type