I used to discuss this issue quite extensively on my previous profile and I think it would be a good idea to re-create my discussions on these points. Especially today as the issue of credentialism and epistemic authority and trust has re-surfaced in an aggressive way, I think a framework on how our knowledge is dependent on others is crucial for navigating these issues.

Today “social epistemology” is the name for a sub-division of epistemology which deals with the acquisition and justification of knowledge which we acquire from others. In the past this would simply be discussed under the topic of “testimony and authority” where we learn of something from the testimony of another. While “authority” maybe a strange word to use here given its political connotations, in English we actually still use the word “authority” in this epistemic sense when we say, “I have it on good authority that he has already arrived in town”, what we mean by “authority” here has nothing to do with legal or political authorisation but rather that one has a *reliable source* of information for a claim. We also say things like, “This man is an authority on quantum mechanics”, again, this has nothing to do with legal or political authority but that he is an expert on the topic and as such is a reliable source of information for quantum mechanics.

It is clear that 90% of our knowledge is pretty much acquired on the word of someone else. Even if we were the most competent scientist on earth, we simply lack time and mental bandwidth to test and verify everything ourselves, we are necessarily dependent on the word of others. And there are other claims where it is simply impossible to verify for ourselves, e.g. knowledge of past events. We cannot as it were build a time machine to witness the Battle of Waterloo for ourselves.

However today social epistemology is pretty much banished to the sidelines of epistemology and studied as a highly specialised and esoteric topic, while in the past the arts of evaluating testimony and authority would simply have been studied side by side any logic or rhetoric textbook. This may explain why our capacity to interrogate and judiciously evaluate sources of information has completely atrophied, swing wildly between blind trust in “the Science” or just systematic skepticism of anything.

The denigration of social epistemology however has very deep roots in Western philosophy itself. There is a reason why we are captured by the image of the philosopher who contemplates realities and the Truth via introspective reflection and reasoning rather than from hearing it from others. Plato classified belief from authority as mere “opinion” and unworthy of the status of knowledge which can only be secured by reason and deduction from first principles, Aristotle was better and discussed testimonial knowledge at some length, but he still ranked it lower than “demonstrative knowledge” or “science”. With Christendom however and the elevation of the centrality of the apostolic testimony to Christ, knowledge from testimony and authority obviously became central again. However knowledge from authority was challenged by the scholastic revival of the classical schools which threatened the status of testimonial knowledge in place of allegedly superior and surer metaphysical deductions from first principles. With the Renaissance and Reformation, and the call to return to the sources, testimonial knowledge was once more elevated, until the British Enlightenment and the Scottish Common Sense school finally elevated testimonial knowledge to pride of place side by side and equal to “demonstrative” or scientific knowledge.

So much for a brief history of testimonial knowledge. To introduce the topic proper I think it would be useful to quote at some length from Cicero’s classic summary of knowledge from “authority” or testimony. Cicero discusses this as a lawyer needing to locate “authoritative” sources of knowledge to create belief in a claim, however I think the factors he considers relevant would be a useful summary to the key elements of the topic:

This sort of argumentation then which is said not to be founded on art, depends on testimony. But we call everything testimony which is deduced from any external circumstances for the purpose of implanting belief. Now it is not every one who is of sufficient weight to give valid testimony; for authority is requisite to make us believe things. But it is either a man’s natural character or his age which invests him with authority. The authority derived from a man’s natural character depends chiefly on his virtue; but on his age there are many things which confer authority; genius, power, fortune, skill, experience, necessity, and sometimes even a concourse of accidental circumstances. For men think able and opulent men, and men who have been esteemed during a long period of their lives, worthy of being believed. Perhaps they are not always right; but still it is not easy to change the sentiments of the common people; and both those who form judgments and those who adopt vague opinions shape everything with reference to them. For those men who are eminent for those qualities which I have mentioned, seem to be eminent for virtue itself. But in the other circumstances also which I have just enumerated, although there is in them no appearance of virtue, still sometimes belief is confirmed by them, if either any skill is displayed,- for the influence of knowledge in inspiring belief is very great; or any experience,- for people are apt to believe those who are men of experience.

[…]

We may also put in this class public opinion, which is a kind of testimony of the multitude.

But those things which create belief on account of the virtue of the witness are of a two-fold kind; one of which is valid on account of nature, the other by industry. For the virtue of the gods is eminent by nature; but that of men, because of their industry.

Testimonies of this kind are nearly divine: first of all, that of oration, (for oracles were so called from that very same word, as there is in them the oration of the gods;) then that of things in which there are, as it were, many divine works; first of all, the word itself, and its whole order and ornaments; then the airy flights and songs of birds; then the sound and heat of that same air; and the numerous prodigies of divers kinds seen on the earth; and also, the power of foreseeing the future by means of the entrails of victims: many things, too, which are shown to the living by those who are asleep: from all which topics the testimonies of the gods are at times adduced so as to create belief.

In the case of a man, the opinion of his virtue is of the greatest weight. For opinion goes to this extent, that those men have virtue, not only who do really possess it, but those also who appear to possess it. Therefore, those men whom they see endowed with genius and diligence and learning, and whose life they see is consistent and approved of, like Cato, and Laelius, and Scipio, and many others, they consider such men as they themselves would wish to be. And not only do they think them such who enjoy honours conferred on them by the people, and who busy themselves with affairs of state, but also those who are orators, and philosophers, and poets, and historians; from whose sayings and writings authority is often sought for to establish belief.

Topica

We note that at points Cicero injects a note of skepticism into his criteria, for example that people tend to think that the rich and those who have lived long lives have additional authority even if “Perhaps they are not always right; but still it is not easy to change the sentiments of the common people”.

However, evaluating testimonial arguments have come a very long way since Aristotle and Cicero especially with our modern highly developed law of evidence. We can generally divide testimonial authority into two kinds (1) Witness and (2) Expert.

(1) Witness: If you have personally seen something, or heard something from someone that would constitute “witness”. As the term suggests, a “witness” testifies to having seen something himself with his own senses. It should be obvious here that of the list of things which gives an authority “witness”, honesty and an interest to witness to the truth are much more relevant than age, expertise or wealth, etc.

(2) Expert: Then we have “experts” whose authority you trust on the basis of their wisdom, learning, and expertise concerning the subject matter at hand. Thus, credentialling here will create authority for an expert as evidence that he has put in the labour to master the topic and as such is a reliable source of information for it.

To use a Church Father as an example of this distinction, when Jerome tells us that he has seen a Gospel of Matthew in Hebrew, he is speaking as a personal witness; when Jerome on the other hand makes theological arguments about the nature of Christ, he is speaking as an “expert”.

Once we understand the nature of testimonial knowledge, how the object to which one testifies is related to the person testifying, we then have the analytical means to determine what sort of criteria is relevant for determining the reliability of a witness. As already mentioned, age and wisdom aren’t really relevant features for eyewitness testimonies, while depending on a topic, a young scientist would have a better command of a new emerging discovery and field, or on the other hand, an experienced old hand would be a better authority on a relatively stable field like the behaviour of animals on his farm.

I’ve so far only painted this topic in very broad brushstrokes, however there are a whole constellation of concepts associated with social epistemology, e.g. the epistemic division of labour, epistemic institutions, interest and bias in testimonies, etc, etc. But I believe that this topic does provide a sufficient conceptual resources for further thought on this topic.