Johanna Wolff (Hong Kong) gives a talk at the MCMP Colloquium (8 July, 2015) titled "Realism about Measurement and Realism about Magnitudes". Abstract: A realist about measurement, roughly speaking, holds that measurements give us information about, or epistemic access to, the way the world is. Measurement, on such an account, is objective. A realist about magnitudes, understood either as properties or relations, holds that the way measurements provide such objective knowledge is by tracking features of the world, namely certain quantitative properties or relations. Does realism about measurement require realism about magnitudes, or can we be realists about measurement without any additional commitment to magnitudes? Operationalists (Bridgman 1927, Stevens 1935) and nominalists (Field 1980) have traditionally held that it is possible to be a realist about measurement without being a realist about magnitudes. Realism about measurement without realism about magnitudes also seems to be promoted by Representationalism about measurement (Krantz et. al. 1971-90). Against these attempts to divorce realism about measurement from realism about magnitudes, Mundy (1987), Swoyer (1989), and more recently Peacocke (forthcoming) have argued that realism about measurement, while conceptually distinct from realism about magnitudes, nonetheless requires a commitment to magnitudes. My primary question in this paper is how exactly we should understand realism about measurement and realism about magnitudes respectively. A secondary aim will be to see how traditional arguments in favour of realism about magnitudes fare, depending on how we understand these two realisms.