Chapter 6 The Metaphysics of the Model-Theoretic Arguments Kate Hodesdon Abstract This paper presents a exposition of Putnam’s model theoretic arguments in the context of his broader philosophical position. I argue that Putnam used the arguments not just to undermine metaphysical realism, but to reveal that the philo- sophical debate between metaphysical realism and internal realism is dialectically problematic in that the metaphysical realist defence cannot “count against” (Putnam in Philosophical Topics: The philosophy of Hilary Putnam 20(1):355, 1992c) the converse position. Putnam’s response is that this is a debate that we should simply undercut. Putnam’s model theoretic arguments have posed challenges of interpretation since their publication. In this article I shall make two claims about the arguments that add to this debate. One is to clarify the arguments’ target: while it is clear that the arguments are designed to refute the position of metaphysical realism, it is less clear just which hypothesis is at stake. I present a thesis that Putnam takes to be constitutive of metaphysical realism and targets with the model-theoretic arguments. This is the posit of epistemic humility, which states that it is possible that there is an aspect of the world that is epistemically inaccessible as a matter of principle. The second aim of this paper is to suggest a new direction in which to seek justification for the notorious ‘just more theory’ response that Putnam gives to critics of the model-theoretic arguments. Metaphysical or “external” realism and Putnam’s own internal realism are broad positions, comprising two “philosophical temperaments” (1981, p. 49) or “tenden- cies” (1980, p. 474). They are also foundational: Putnam hints that their consequences affect almost every area of philosophy (1981, p. 49), particularly scepticism (“the question of‘Brains in a Vat’ would not be of interest if it were not for the sharp way in which it brings out the difference between these philosophical perspectives”; Ibid.) The distinction between the two positions is inspired by Kant, with internal realism representing Kant’s own position (1992d, p. 114, 1987, pp. 36–37), although the relationship between Kant and Putnam’s views is complicated. Metaphysical real- K. Hodesdon (B ) Department of Philosophy, University of Bristol, Bristol, UK e-mail: kate@hodesdon.com © Springer Nature Switzerland AG 2018 G. Hellman and R. T. Cook (eds.), Hilary Putnam on Logic and Mathematics, Outstanding Contributions to Logic 9, https://doi.org/10.1007/978-3-319-96274-0_6 75