TITLE: Conceptual structuralism and continuum hypothesis
QUESTION [11 upvotes]: In Ferefman's paper 'Is the Continuum Hypothesis a definite mathematical problem?', he argues that within the philosophy of conceptual structuralism, the continuum hypothesis is not a definite mathematical problem.
However, Koellner wrote a response to this paper in his paper 'Feferman on the Indefiniteness of CH'. In this, he proposes that it is possible to reach the conclusion that the continuum hypothesis is a definite mathematical problem via conceptual structuralism though he presents no argument for it. Instead, he relates this to the views of Martin and Isaacson.
Does anyone know where I can find an argument that the continuum hypothesis is a definite mathematical problem by the view of a conceptual structuralist?

REPLY [11 votes]: Koellner is probably referring to the paper

Daniel Isaacson, The reality of mathematics and the case of set theory, in: Zsolt Novak and Andras Simonyi (eds), Truth, Reference, and Realism, Central European University Press, 2011. JSTOR
(author pdf).

Isaacson appeals to Kreisel's argument that the second-order categoricity of set theory makes the continuum hypothesis a definite problem.