Thomas Reid on Testimony

As part of a project I am doing on religious experience, skepticism, and testimony, I have been reading Thomas Reid's An Inquiry into the Human Mind: on the Principles of Common Sense. In Section XXIV, entitled Of the Analogy between Perception, and the Credit we give to Human Testimony, Thomas Reid's fundamental recognition is of the basicality of human testimony in the acquiring and justifying of beliefs and the strong analogy between knowledge gotten by way of perception and knowledge attained as mediated by other persons:


"The objects of human knowledge are innumerable, but the channels by which it is conveyed to the mind are few. Among these, the perception of external things by our senses, and the informations which we receive upon human testimony, are not the least considerable" (Reid, 228.)


Although the notion that much of our knowledge relies upon trusting the veracity of other peoples' word tends to upset our Enlightenment constitution, Reid's point is an important one; one that I hope to utilize in a somewhat modified argument from religious experience for the existence of God (but more of that in another post).
Thomas Reid begins by making a distinction between original and acquired perception, and natural and artificial language. There is, he says, a great analogy between acquired perception and artificial language, but there is a stronger connection between original perception and natural language. Man's original perception is said to understand a sign; this sign is representative of reality. It is the interpretation of how the sign connects to what it symbolizes that yields a belief within a given man. What makes this faculty original, argue Reid, is that our ability to interpret the sign is itself implanted by nature; we have within us a natural understanding of the relationship between, say, the cooing sound of our mother's voice and her actual face and body. Similarly, Reid posits a relationship between the signs of the body (gestures, tone, etc...) and the thoughts and dispensations of the mind that are perceived in our ability of natural language. As is the case with original perception, our capability to understand this relationship is implanted in us from birth; it is something 'natural' in the sense that we need not cultivate or develop it in order for it to function.
On the other end of the spectrum we have what Thomas Reid calls acquired perception and artificial language; both of these faculties understand a connection that exists between signs and reality as is the case with the original perception and natural language. Acquired perception discovers the relationship between novel signs (sensations) and a novel reality (say, a skyscraper or the ocean) by experience; this understanding is not innate as it is in original perception and thus must be honed. Analogously, our capacity for Reid's artificial language is said to discover the connection between particular articulated sounds (novel words or phrases, new semantics, or grammatical arrangements) and a man's thoughts and intentions; thus beliefs about the relation between the two are grounded in experience. Suppose I encounter a new word that has been circulating around my University lately, Word X. If I have never heard Word X before, apart from asking someone outright for a definition, I would likely come to understand its meaning only if I paid close attention to the way it was being used in sentences, its similarity to other words I already knew, and the like. My understanding of the connection between these syntactical, grammatical, and semantic clues and the actual meaning of the word would be what Reid would call my artificial language. Eventually, says Reid, I would come to form principles (something akin to concepts) and would be able to form generally accurate predictions about the meaning of new words through my artificial language and perceive the reality of novel objects through my acquired perception. I would come to understand that when such-and-such a sensation is present within me, an object with such-and-such properties is probably the cause of my sensation.


"There is, therefore, in the human mind an early anticipation, neither derived from experience, nor from reason, nor from any compact of promise, that our fellow creatures will use the same signs in language when they have the same sentiments.... The wise and beneficent Author of nature, who intended that we should be social creatures, and that we should receive the greatest and most important part of our knowledge by the information of others, hath, for these purposes, implanted in our natures two principles that tally with eachother" (Reid 231.)


These principles, says Thomas Reid, are first the propensity to speak the truth, to use the signs of language so as to convey our real sentiments, and second the "disposition to confide in the veracity of others." This second principle Reid dubs the principle of credulity. Richard Swinburne, in both his The Existence of God (p. 305) and his Epistemic Justification (pp. 141-50) devises a similar axiom by the same name. Alvin Plantinga, too, mentions Thomas Reid's principle in Warrant and Proper Function (p. 77). If humans are not implanted with a tendancy to accept prima facie what others have told us, Reid reasons, no proposition would go unexamined; we would be inclined to filter each and every report through reason and experience, weighing each testimony about the world against the evidence. This, says Reid, is obviously not the case. Even the most skeptical of us do not carefully and logically asses each and every claim we receive from others. This, to me, seems to be right. When I hear on the 7 o'clock news that there was a nasty accident on the highway, my first reaction is not skepticism, but epistemic assent. I tend to believe that I am told. Moreover, even witnesses that are perceived as less reliable than news organizations I generally meet with little to no skepticism. If my neighbor Fred comes over and tells me that his house was broken into last night, I take his claim at face value and adopt the belief, Fred's house was broken into last night into my epistemic web. Reid's principle of credulity is a kind of "innocent until proven guilty" with respect to the veracity of human testimony.
In addition to his argument from our apparent casual usage of the principle of credulity, Reid mounts a pragmatic argument in its favor: "...distrust and incredulity would deprive us of the greatest benefits of society, and place us in a worse condition than that of savages." Here, he makes the obvious point that without the normatization of the principle of credulity, human knowledge would diminish to a destructively low level; society itself would decline, and distrust and incredulity would slowly degrade our modern society. Thus, Reid argues, one ought to believe others about their testimony, at least prima facie.
Insofar as the principle of credulity relates to Thomas Reid's previous arguments about language and perception, we should here note that if, as a general rule, we should believe others, then it follows that we should believe others about specifics, such as the deliverances of their own acquired perception and artificial language. If, for instance, I observe my colleagues using Word X in a certain way, and I decide to take a stab at using Word X, I ought to follow their example and use it in the sense that they do. Similarly, if I am told that a number of people have just in the last few moments been appeared to in a rose-like way, I ought to first believe that this is probably not a lie (unless I know them to have good reason for deceiving me) and thus second that there probably was something rose-like that appeared to them in such a way so as to cause them to have a rose-like experience (since the best explanation for multiple experiences of a rose-like qualia is usually not hallucination or deception, but actual perception).
What exactly Thomas Reid's common-sense approach to testimony and credulity means for religion and religious experience is a topic I intend to explore soon.