This article shows why it is important to do normative or practical philosophy of science, especially philosophy of science that criticizes and evaluates contemporary use of scientific methods to analyze welfare-affecting societal problems. The article introduces the scientific, ethical, and social problem of environmental injustice—disproportionate environmental and pollution threats that are responsible for roughly 40% of all preventable disease and death. Next it explains that many deadly threats continue in part because of “special-interest science”, methodologically flawed science that is done (...) to promote corporate profits, rather than truth, then argues that philosophers of science should use normative or practical philosophy of science to critique and expose special-interest science. To illustrate special-interest science, the article provides two case studies, on diesel-particulate-matter pollution and on organophophate-pesticide pollution, and shows how diesel and pesticide polluters use special-interest science. For instance, they often ignore observational data, illegitimately demand statistically significant evidence of harm from observational data, use small sample sizes, do the wrong tests, or demand certainty—rather than a preponderance of evidence—to justify a conclusion about pollution harm. They also use flawed normative arguments to defend both diesel and pesticide pollution. The article concludes that, given the epistemic, scientific, human-welfare toll of special-interest science, philosophers of science need to do normative or practical philosophy of science that exposes these scientific flaws. (shrink)