The scientific or rational approach is one of pure description—insofar as that ideal is even possible—with any prescriptions being included only when laid bare as the descriptions that they must ultimately be. For example, when thinking scientifically or rationally it’s perfectly reasonable to give an argument of the following logical form: “X causes Y. You want Y. Therefore, you should also want X.” Whether X actually causes Y, and whether you actually want Y, are separate questions; they’re questions that can be debated. What’s important to emphasize here is simply that science doesn’t hide value judgments but puts them out in the open for all to see. You can describe a person’s value judgments, and in some cases you may even be able to tell them something about their value judgments that they’re not already consciously aware of. But science always does its best to untangle judgments of value from beliefs in cause and effect. The ideal of science is to offer propositions only in an ultimately purely descriptive way, whether or not any prescriptions are in turn logically implied.

That is, scientific propositions are always perspective-neutral in their formulation, though it’s of course possible for each person to plug in their own value judgments and then in effect get advice on what to do.

To be clear: It’s not that the scientific approach doesn’t let you tell people what they should do. It’s just that the scientific approach lays bare the logical steps of the argument; it untangles value from belief. It doesn’t preach: “Do X, for X is right and good.” Instead, it says (much more nihilistically than any preacher would): “If you want Y, then you should do X.” Science is a tool, and like any other tool it’s itself agnostic about what people use it for. More concretely, science is analogous to a knife in that, e.g., a chef can use a knife to cut an onion, yes, but a mugger can also use that same knife for a much different purpose.