  Jeffery Ketland (2004) argues in detail that the Newman objection trivialises the Ramsey sentence formulation of ESR. Worrall and Zahar (2001) argue that the cognitive content of a theory is exhausted by its Ramsey sentences but that, while the Ramsey sentence only expresses the empirical content of the theory, the notion of empirical content in play here is sufficient for a form of realism. In his 2007 paper, Worrall sets out an account and defense of epistemic structural realism and responds to objections that have been raised to it, including the Newman problem. Cruse (2005) and Melia and Saatsi (2006) defend the Ramsey sentence approach against model-theoretic arguments by questioning the assumption that all predicates which apply to unobservables must be eliminated in favour of bound variables. Mixed predicates such as ‘extended’ are those that apply to both observable and unobservable objects. The Newman objection does not go through if mixed predicates are not Ramsified, because a model of the Ramsey sentence will not necessarily be one in which what is claimed regarding the mixed properties and relations holds. In response, Demopoulos (2008) points out that the Ramsey sentence of a theory with mixed predicates where the latter are not Ramsified will be true provided the original theory is satisfied—hence the claim that the content of the Ramsey sentence is merely the observational content of the original theory plus a cardinality claim is still true when mixed predicates are considered. Melia and Saatsi (2006) also argue that intensional notions, such as naturalness and causal significance, may be applied to properties to save the Ramsey sentence formulation of ESR from triviality. (This recalls the defence of Russell's structuralism against Newman discussed in Hochberg 1994.) Demopoulos also raises two problems with this strategy: firstly, even non-natural relations can have significant claims made about them in a theory, and secondly, the cognitive significance of unramsified theories is independent of a commitment to ‘real’ or ‘natural’ relations.  Hence, Demopoulos insists that the Ramsey sentence of a theory and the theory itself are importantly different (see also Psillos 2006b). Peter Ainsworth (2009) gives a clear and accessible account of the Newman problem and the responses that have been given to it. In his (2011) Demopoulos argues that there are three very different views in the work of Russell, Ramsey, and Carnap respectively, which have in common versions of a core structuralist thesis that he identifies. All the accounts he considers make use of Ramsey sentences; Demopoulos investigates the logical properties of the Ramsey sentence and arrives at an argument against the structuralist thesis. Friedman (2011) argues that Carnap’s account of theoretical terms involving the Ramsey sentence approach is not vulnerable to the Newman problem. The relationship between Friedman's views on the relativized a priori and structural realism is interrogated in Ivanova (2011).