 The central thesis of Kant’s account of the uniqueness of mathematical reasoning is his claim that mathematical cognition derives from the “construction” of its concepts: “to construct a concept means to exhibit a priori the intuition corresponding to it” (A713/B741) (Friedman 1992, 2010; Shabel 2006). For example, while the concept &lt;triangle&gt; can be discursively defined as a rectilinear figure contained by three straight lines (as is done in Euclid’s Elements), the concept is constructed, in Kant’s technical sense of the term, only when a corresponding intuition is exhibited; in this case, the corresponding intuition is a singular and immediately evident representation of a three-sided figure. Kant argues that when one so renders a triangle for the purposes of performing the auxiliary constructive steps necessary for geometric proof, one does so a priori, whether the triangle is produced on paper or only in the imagination. This is because in neither case does the object displayed borrow its pattern from any experience (A713/B741). Moreover, one can derive universal truths about all triangles from such a singular display of an individual triangle since the particular determinations of the displayed object, e.g., the magnitude of its sides and angles, are “entirely indifferent” to the rendered triangle as an exhibition of the general concept &lt;triangle&gt; (A714/B742). Kant’s account must thus be defended against the commonly held position that universal truths cannot be derived from reasoning that depends on particular representations (Friedman 2012, 2020). Relatedly, the less than perfectly straight sides of an empirically rendered triangle are similarly “indifferent” to the general concept &lt;triangle&gt; and so such an empirical intuition is considered adequate for geometric proof. This raises questions about how one can be sure that an intuition adequately displays the content of a concept (Dunlop 2012); the relation between pure and empirical intuition (Friedman 2012; Shabel 2003); and, in particular, which of the intuitively displayed features can safely be ignored (Friedman 2010, 2012). These features of Kant’s theory of construction also invite discussion about the acquisition conditions of mathematical concepts (Callanan 2014); the role of construction in indirect reductio proofs (Goodwin 2018); the relation between construction and definition (Heis 2014, 2020; Nunez 2014); and the role of imagination in construction (Land 2014).