 Philosophically speaking, there is a large question mark over whether the dual pair should be seen as genuinely distinct in a physical sense or as mere notational variants of the same theory — talk of a “dictionary” relating the theories makes the latter more palatable and suggests that the choice of physical interpretation might be conventional. However, if we view the theories as notational variants, then our sense of theory-individuation is seemingly compromised, since the dual pairs involve different dynamics and degrees of freedom. (See Joseph Polchinski 2014, for a thorough account of the various kinds of dualities along with some of their interpretive quirks; Rickles 2011 provides a philosophical examination of string dualities.) 