This makes room for methodological naturalists to insist that most primary philosophical concerns are synthetic and a posteriori, even if they imply additional modal claims which are not. Natural science provides a good analogy here. Water is H2O. Heat is molecular motion. Stars are made of hot gas. Halley’s comet is made of rock and ice. Since all these claims concern matters of identity and constitution, they too are necessary if true. But science is interested in these synthetic a posteriori claims as such, rather than their modal implications. Chemistry is interested in the composition of actual water, and not with what happens in other possible worlds. Methodological naturalists can take the same line with philosophical claims. Their focus is on whether knowledge is actually the same as true justified belief, or whether persisting objects are actually composed of temporal parts—issues which they take to be synthetic and a posteriori—and not with whether these truths are necessary—issues which may well have a different status.