 To see the third worry with Global Reductionism, notice that Global Reductionists treat testimony as if it is a unified, homogeneous category, i.e., according to Global Reductionists, testimony in general can be a more or less reliable source of knowledge. The problem here is that we frequently receive testimony about wildly different topics, e.g., quantum mechanics, politics, one’s own music preferences, etc. And clearly testimony about some of these things is highly reliable (e.g., all of your friends are probably very good at speaking truly about what kinds of music they like), whereas testimony about other topics is less so (e.g., if your friends are like mine, then at least a few of them are probably a lot less reliable at speaking truly about politics). Thus, contra Global Reductionism, it is a mistake to treat testimony as a unified source of knowledge; that is, instead of thinking about testimony in general, we should think about the various categories of testimony in particular, e.g., categories differentiated by subject matter. For it is only when we think of testimony as being disaggregated in this way that it make sense to ask about whether receiving testimony about a particular category is a reliable source of knowledge. See, e.g., E. Fricker (1994).