 It should also be noted that, according to Vickers himself, the employment of condition 3′ in dealing with PI seems to bring scientific realism dangerously close to structural realism. As has already been said, Vickers’s recipe for handling a PI-style challenge is roughly the following: take the (false) hypothesis \(H\) that, according to the anti-realist, is employed in the derivation of a prediction \(P\), identify an (uncontested) \(H^*\) which is entailed by \(H\) and show that \(H^*\) is enough for the derivation of \(P\). This recipe goes a long way in disarming Lyon’s objection. And yet, Vickers notes, an even weaker hypothesis \(H^{**}\) is available, viz., that for the prediction of P only the mathematical structure of \(H^*\) is required. But then, “only the very abstract ‘structure’ truly merits realist commitment, as structural realists like to claim” (2017: 3227). If we take ‘structure’ to be identified with the Ramsey sentence of a given theory (see the next section), then Vickers’ concern is, at least prima facie, a plausible one. For the Ramsey sentence of a theory is obviously entailed by the latter and, as is well known, any theory and its Ramsey sentence have exactly the same observational consequences. Hence, it seems that the employment of condition 3′ forces realists to restrict their commitment solely towards the Ramsey sentences of their favoured theories. In reply, however, it should be stressed that though Vickers’s concern is prima facie warranted, it is far from conclusive. In fact, after raising his concern, Vickers doesn’t further explore it, whereas Alai (2021: 211–212) has argued that from the mere application of condition 3′ “it doesn’t follow that every hypothesis is dispensable in favor of its Ramsey sentence”.