There are two primary positions in philosophy of testimony. The reductionist position (generally associated with David Hume) says that our only warrant for believing testimony is underlying evidence associating it with the truth: things like the speaker’s having been present at the scene, or that she has generally reported facts reliably, or that he has properly functioning senses. On this view the testimony is only a conduit through which other justifications flow.
The anti-reductionist position (associated with Thomas Reid and more recently with Coady) says that testimony offers independent warrant for belief or knowledge. Those subscribing to this position vary in the extent to which this occurs, but in general it is the sense that we are justified in believing testimony in the absence of defeaters (specific reasons not to believe it). Generally this justification is viewed as somehow a priori, part of the nature of knowledge, which makes sense since otherwise we would be claiming that it required some independent justification.
I am not a fan of a priori knowledge, but it is also clear that if we take a radical empirical-reductionist approach to testimony, we will have lost a great deal of efficiency if not our entire ability to function. How can we reconcile this?
A relatively simple answer occurred to me today. It requires considerably more investigation on my part to get the details right, but the idea is straightforward. It is that there is an independent warrant provided by testimony, and it holds this warrant through convention.
In Searle’s The Construction of Social Reality, and Austin’s How to Do Things with Words, we see how some facts of reality are created by social convention. This does not mean that reality itself is entirely a social construct - it means that in a social context, some things are true that would not be true outside that context. Money is a favorite example: the pieces of paper you use to buy a candy bar at the convenience store would not function to obtain food if you were stranded on a desert isle, or even for that matter in a country that does not accept the particular pieces of paper in question. Bitcoin is an even clearer example since it does not even have the backing of government. Other examples include status questions like marriage and job titles, or pervasive elements such as language generally and the meanings of words in particular.
Searle captures this notion as “X counts as Y in context C.” We can apply that formula to testimony. In particular social contexts (C), testimony (X) counts as knowledge (Y). It is not just that we trust people in that context, or that we have empirical reasons to believe them. It is specifically and independently that we have a social convention of believing what people say. Though in many situations we might be on the lookout for defeaters, we have a strong presumption that people are speaking the truth in that context.
This makes it fairly easy to see what is going on today in the United States and perhaps elsewhere. This social convention has partially broken down, particularly with respect to journalism and to some extent with respect to science. Without getting into the sociology and the causes, it is clear that our presumption of truth is much weaker than previously and in some cases it has been eliminated. There has arisen an army of skeptics, of a variety of persuasions, willing to challenge any article of testimony if it does not suit their political or moral preferences. The only apparent substitute is a thoroughly reductionist approach, where we expend a great deal of energy attempting to verify claims, and only trust individuals and institutions after they have proved themselves extensively. In the absence of the social convention of presumption of truth, or an elaborate system of verification, we risk epistemic nihilism, where we have a sense that we don’t really know the truth about much of anything.
It is not at all clear whether or how we can re-establish the convention of generally believing testimony. What is clear is that its effects go far beyond mere abstract questions of knowledge justification. We are seeing first-hand that a democratic society relies utterly on this social convention, for if we do not know whether elections are real or who is telling the truth about them, then how can the institutions of democracy function?