Abstract
In metaphysics, we seem to have in every generation an oscillation between realist positions and stances that are in one way or another idealist, instrumentalist, or constructivist. Realists in the philosophy of science are those philosophers who will not conclude, from the fact that scientific theories are undoubtedly constructs of human mentality and culture, that therefore the content of these theories is inevitably some function of the human mentality and culture that have produced them. Realists are unimpressed by response-dependence. Realism is metaphysical optimism; it has not abandoned the notion that exercising our capacities does not disqualify us from discovery.