What I designate as “opaque" epistemic dependence is the kind of dependence that epistemologists usually talk about. It is the extreme case of an epistemic dependence relation, the relation that Hardwig describes and that can be formulated as a testimonial exchange: Speaker B tells listener A that p, and A has no means to establish the truth that p other than assuming that B is a competent and truthful testifier. A has no way whatsoever to justify her believing that p without recourse to B, because A lacks the expertise to acquire the justified belief that p by means other than reliance upon B’s testimony. Nevertheless, she can try to establish the reliability of B, and succeed in doing so to varying degrees. The more A knows about B, his moral and professional qualities, the better she can judge his qualities as a testifier that p without possessing expertise pertaining to p herself. Thus, the dependent person in opaque dependency relations should not be described as completely naive, ignorant or undiscerning. She can have, as Hardwig pointed out, very good second-order reasons to enter an opaque dependency relation.
A lack of expertise cannot easily be mitigated. Expertise cannot be simply learned from the book. The acquisition of scientific expertise is a complex learning process that typically stretches over years. Therefore, exemplary cases of opaque dependence can be found in both groups studied. In the planetary science group, instances of opaque epistemic dependence are particularly apparent because the group has an interdisciplinary profile. In this group, scientists with different disciplinary backgrounds collaborate in an intricately interwoven manner. Every one of them contributes to their collaboration with the particular combination of epistemically relevant resources he or she possesses. The use of the group’s simulation facility by members without physical expertise is a good illustration of opaque epistemic dependence. When the biologist runs an experiment in the group’s simulation facility, he or she relies entirely upon Adam, the physicist who is responsible for this facility.
The biologist is not able to operate the simulation facility, so he or she delivers a bacterial sample to the physicist who then places the sample in the facility, runs the experiment and returns the sample afterward to the biologist for further laboratory analysis. The physicist will also report on the measurement of all experimental parameters, such as wind speed. Another example of opaque dependence in the planetary science group would be the reliance upon Moessbauer spectroscopy to determine the iron components in geological samples. This is an example that Laurits, the group’s geologist, brings up during our interview:
Q: Mhm. Do you think that the things you have in your papers, in principle you could do them on your own? Or you could only do them with others? Laurits: Ahm, if I think back I would say that, that ahm, in many of our publications Moessbauer spectroscopy has been used as a useful method.
I started with that before Rasmus [physicist in groupl] came here. With the Moessbauer laboratory in Physics. And I started to publish things ahm with one of the persons from there, so I knew or I never had, it hasn’t been necessary for me to do Moessbauer spectroscopy myself. And it’s a field where you need a lot of experience to be sure of what you interpret out of the spectra you see. So, I would not be able to get the same interpretation out of that if, if I didn’t have an expert like Rasmus. So that, this wouldn’t be a good way doing publications, try to do this as an amateur yourself. So you need to collaborate with people that know more about different fields. And when it comes to sand transport, I would say that Oliver [geologist associated to groupl] has used all his life on that and he of course has a basic knowledge there that I don’t have. So if we come to experience and publications in that field, I would never do it without him. (Laurits, senior geologist, groupl)
Instances of opaque dependence relations come to the fore in the molecular biology laboratory as well. There are two sources of epistemic opacity here. The first source is a learning lag between less experienced and more experienced group members, and the second source is specialization, both in vertical and horizontal forms. Paradigmatic for within-group relations in the molecular biology laboratory is the first source of opacity. Opaque epistemic dependence typically characterizes students’ relation to senior scientists. For PhD students it is key to rely on the hands-on expertise of junior group leaders for the purification and crystallization of particular families of proteins. For example, Martin, a new PhD student, depends crucially on a post-doc’s skills (Magnus) for the treatment of proteins that are known to require particularly intricate purification procedures. At the time of my interview with Martin, however, it was clear that Magnus would be leaving the laboratory soon to start his own group at a different university.
Q: Magnus is leaving, is that a problem?
Martin: I don’t know. Initially I was very anxious about that, but I feel that we are getting to a point that within, because we have progress, basically, I think that within two months let’s say we can do everything, like, because after he gave us the basic experiences, then we have to just fiddle around by ourselves. Also Magnus is very accessible by emails, skype and he clearly wants to help us and he said that of course he wants to consult with us. If we got further, then it’s not really, his experience stops to be that necessary. (Martin, PhD student in molecular biology, group2)
Here, opacity has, or is imagined to have, a transient character. Time is a crucial element in understanding these dependency relations. Because of a lack of experience, junior researchers rely on senior ones, though the former expect to gain the professional capacity they are lacking at some point in the future. As students’ expertise grows, they develop greater professional autonomy.
-  Strategies for establishing second-order reasons for the reliance upon a collaborator are analyzed inGoldman (2001) and Sperber et al. (2010).