Rene Descartes proposed that we need to find the limit of human understanding so that we may restrict thought within those limits. He thereby launched the modernist period in philosophy, especially for British/Scottish empiricism. I propose thinking scientific naturalism as a legacy of this circumscription of thought.
Scientific naturalism, as a metaphysical thesis, holds that what is real are the objects of science, and science studies nature. Many distinctions may be made, but for the most part and in this context, objections are reducible to this point. In Cartesian terms, I would characterize scientific naturalism as limiting proper thought to what contemporary science can best prove, which is what I take to be its paradigmatic trait.
A problem with this is that separations between vetted thought and actual thought cannot de facto occur and de jure should not be attempted, because we then misunderstand the nature of thought and the basis of scientific claims. In essence, scientifical naturalism is not coherent or even self-consistent if we measure recent neuro- and cognitive science against the self-assured claims of scientific naturalism. It’s an ideal that we cannot hold and is not a good regulatory ideal. It ensconces false notions of human powers and systematizes hubris. This is not a new claim, and has been made from many traditions of philosophy. My personal favorite expressions of this critique are Helen Longino’s Science as Social Practice (analytic), John Dewey’s Experience and Nature (pragmatism), and the pair of Edmund Husserl’s Crisis of the European Sciences and Martin Heidegger’s “Question Concerning Technology” (continental per phenomenology).
I prefer the former two, though I grant the theoretical powerhouses of the latter two, because Dewey and Longino share an emphasis on practice as a solution. I would rather affect positive change than be intellectually justified. The former is more difficult and more valuable, but the latter is something accomplishable upon one’s own merits and without so much good fortune.