First, string theory is an extension of the quantum field theory program of high energy physics (HEP), and so bound by the methodological constraints of that program: for instance, candidate theories lie within the framework of path integral QM developed by Richard Feynman, and utilize the ideas of gauge symmetry arising from Noether's theorems. Second, Dawid argues that in the history of HEP, theories (a) for which no alternative was known, after searching, and that (b) give explanatory unity to a range of physical systems, have turned out to correctly predict the next generation of phenomena (for instance, the electro-weak theory, confirmed at CERN in the 1970s and '80s). A 'meta'-induction on the success of the HEP methodology leads to the conclusion that a theory that satisfies the HEP constraints will make reliable predictions about the next generation of predictions. And, says Dawid, string theorists correctly identify string theory as such, and so are justified in their confidence.