Why “is at”? —On Quine’s Objection to Carnap’s Aufbau in “Two Dogmas of Empiricism”


  • Ka Ho Lam University of Alberta




In “Two Dogmas”, Quine indicates that Carnap’s Aufbau fails “in principle” to reduce our knowledge of the external world to sense data. This is because in projecting the sensory material to reconstruct the physical world, Carnap gives up the use of operating rules and switches to a procedure informed by general principles. This procedure falls short of providing an eliminative translation for the connective “is at”, which is necessary for the reduction. In dissecting Quine’s objection, I argue that Quine has at best proven the claim that the use of general principles essentially fails the task of radical reductionism. However, in order to establish the conclusion that the Aufbau fails in principle, Quine needs to further vindicate two other claims. They are: first, a switch from operating rules to general principles is necessary; second, the set of general principles Carnap adopts is the best alternative. By disambiguating the notion of “explicit definition” and examining the concept of definability in the Aufbau, I explore the possibility of justifying these two claims that Quine overlooks in his objection. The result suggests that Quine’s objection stands in tension with his radical reductionist reading of the Aufbau.

Author Biography

Ka Ho Lam, University of Alberta



Belnap, Nuel, 1993. “On Rigorous Definitions.” Philosophical Studies 72: 115–46.

Carnap, Rudolf, 1928/1969. Der logische Aufbau der Welt. Berlin: Weltkreis. Translated into English as The Logical Structure of the World, by R. A. George. Berkeley: University of California Press, 1967; reprinted 1969.

———, 1934/2001. Logische Syntax der Sprache. Vienna: Springer. Translated into English as The Logical Syntax of Language, by A. Smeaton. London: Kegan Paul, Trubner & Co., 1937; reprinted London: Routledge, 2001.

———, 1936. “Testability and Meaning.” Philosophy of Science 3: 419–71.

———, 1947. Meaning and Necessity. Chicago: University of Chicago Press.

———, 1952. “Meaning Postulates.” Philosophical Studies 3: 65–73.

———, 1956. “The Methodological Character of Theoretical Concepts.” Minnesota Studies in the Philosophy of Science 1: 38–76.

———, 1963. “Intellectual Autobiography.” In Schilpp (1963), pp. 3–83.

Coffa, J. Alberto, 1991. The Semantic Tradition from Kant to Carnap. Cambridge: Cambridge University Press.

Cohnitz, Daniel and Marcus Rossberg, 2006. Nelson Goodman. Chesham: Acumen.

Creath, Richard, 1982. “Was Carnap a Complete Verificationist in the Aufbau?” PSA: Proceedings of the Biennial Meeting of the Philosophy of Science Association 1: 384–93.

———, ed., 1990. Dear Carnap, Dear Van: The Quine-Carnap Correspondence and Related Work. Berkeley: University of California Press.

Damböck, Christian, ed., 2016. Vienna Circle Institute Yearbook, vol. 18, Influences on the Aufbau. Vienna: Springer.

Føllesdal, Dagfinn and Douglas B. Quine, eds., 2008. Quine in Dialogue. Cambridge, MA: Harvard University Press.

Friedman, Michael, 1987. “Carnap’s Aufbau Reconsidered.” Noûs 21: 521–45.

———, 2007. “The Aufbau and the Rejection of Metaphysics.” In The Cambridge Companion to Carnap, edited by M. Friedman and R. Creath, pp. 129–52. Cambridge: Cambridge University Press.

Goodman, Nelson, 1951. The Structure of Appearance. Cambridge, MA: Harvard University Press.

———, 1963. “The Significance of Der logische Aufbau der Welt.” In Schilpp (1963), pp. 545–58.

Goodman, Nelson and Henry S. Leonard, 1930. “The Calculus of Individuals and Its Uses.” Journal of Symbolic Logic 5: 45–55.

Gupta, Anil, 2015. “Definitions.” The Stanford Encyclopedia of Philosophy, https://plato.stanford.edu/archives/sum2015/entries/definitions/, accessed 27 February 2018.

Leitgeb, Hannes, 2011. “New Life for Carnap’s ‘Aufbau’ ?” Synthese 2: 265–99.

Lewis, David K., 1969. “Policing the Aufbau.” Philosophical Studies 20: 13–17.

Linsky, Bernard, 2016. “Logical Constructions.” The Stanford Encyclopedia of Philosophy, https://plato.stanford.edu/archives/win2016/entries/logical-construction/, accessed 27 February 2018.

Neuber, Matthias, 2016. “Carnap’s Aufbau and the Early Schlick.” In Damböck (2016), pp. 99–114.

Pincock, Christopher, 2002. “Russell’s Influence on Carnap’s ‘Aufbau’.” Synthese 131: 1–37.

———, 2009. “Carnap’s Logical Structure of the World.” Philosophy Compass 4: 951–61.

Quine, W. V., 1951. “Main Trends in Recent Philosophy: Two Dogmas of Empiricism.” The Philosophical Review 60: 20–43.

———, 1964. “Implicit Definition Sustained.” The Journal of Philosophy 61: 71–74.

———, 1969. Ontological Relativity & Other Essays. New York: Columbia University Press.

———, 1984. “Carnap’s Positivistic Travail.” In Føllesdal and Quine (2008), pp. 119–28.

———, 1991. “Two Dogmas in Retrospect.” Canadian Journal of Philosophy 21: 265–74.

———, 1995. From Stimulus to Science. Cambridge, MA: Harvard University Press.

———, 1999. “Response to Lehrer.” In Føllesdal and Quine (2008), p. 261.

Richardson, Alan W., 1998. Carnap’s Construction of the World: The Aufbau and the Emergence of Logical Empiricism. Cambridge: Cambridge University Press.

———, 2016. “External World Problems: The Logical Construction of the World and the ‘Mathematical Core of the External World Hypothesis’.” In Damböck (2016), pp. 1–14.

Russell, Bertrand, 1905. “On Denoting.” Mind 14: 479–93.

———, 1914. “The Relation of Sense-Data to Physics.” Scientia 16: 1–27; suppl. 3–34.

———, 1924. “Logical Atomism.” In Contemporary British Philosophy, edited by J. H. Muirhead, pp. 357–83. London: Allen & Unwin.

Schilpp, Paul Arthur, ed., 1963. The Philosophy of Rudolf Carnap, (The Library of Living Philosophers, vol. XI). La Salle: Open Court.

Suppes, Patrick, 1957. Introduction to Logic. New York: Van Nostrand Reinhold.