Beattie's Essay on Truth, Part I, Chapter 2, is a long section devoted to giving an inductive argument for the position that all human inquiry, and thus all knowledge, is based on first principles. In order to show that his induction is reasonably comprehensive, he runs through the basic ideas underlying his various categories in an interesting footnote. All the objects of understanding, i.e,. things we can genuinely be said to know in some way, are either abstract ideas and relations or things that really exist. If we are speaking of abstract ideas, we are in the realm of mathematical evidence, which consists either of immediate intuitive evidence or the evidence of strict demonstration. If we are talking about what really exists, knowledge is experiential in some way, and we are either talking about our own experiences or someone else's. If we are talking about our own experiences, then we are either talking certainty or probability. If certainty, this pertains to the evidence of external senses, the evidence of internal senses, memory, and legitimate causal inferences from effect to cause. If it is probable, we are arguing either from cases of the same kind, which Beattie calls experimental reasoning, or from cases of a similar kind, which is analogical reasoning. And, of course, if the experiences in question are those of other people, we are speaking of faith in testimony. To put it in outline form.
I. Abstract Ideas and Relations: Mathematical Evidence
II. Things Really Existing
A. Judged by Our Own Experience
A1a. External Senses
A1b. Internal Senses
A1d. Reasoning from Effect to Cause
A2a. From Things of the Same Kind: Experimental Reasoning
A2b. From Things of a Similar Kind: Analogical Reasoning
B. Judged by the Experience of Another: Faith in Testimony
Given the length of this chapter, I won't go into close details, but will simply note some features of Beattie's argument for each. It is important throughout, however, to understand that 'evidence' in Beattie doesn't yet have quite the meaning it does for us; Beattie is writing in a period during which the meaning of the term is shifting. Originally it meant obviousness; for us it meant a reason to think something may be true, which is very weak. In Beattie we can see how the shift from the former to the latter happened, namely, by allowing a pretty straightforward sense in which even probable reason can have obviousness or evidentness; but he still uses the term in a way closer to the original meaning than we do. It's also important to keep in mind a distinction between first principles and conclusions we try to draw from them -- the former can be evident and the latter not, and we can be perfectly right in thinking the former evident while being entirely wrong about the latter being evident. We need this to keep in mind, because each of these categories is a category of inquiry, which may be right or wrong, and Beattie is not arguing otherwise; rather, he is arguing that every such inquiry is based on evident first principles, known by instinct, that we cannot help but think right.
I. Mathematical Evidence
In mathematical reasoning, proofs are supposed to be constituted entirely by evident principles and conclusions from those principles based on evident moves of reasoning, and it is precisely this that gives mathematics its reputation for extraordinary certainty. Thus mathematics has first principles -- very many, in fact; if you refuted them, you would destroy large sections of mathematics, and if you refuse to believe them, you will never get any farther. Refuse to believe, and, even worse, pretend you can refute the first principles, which allow for any mathematical proof in the first place, and you will generally be regarded as a fool or a liar. At the same time, these principles are themselves indemonstrable: no proof we could provide would be more evident, or make the principles more evident, than those principles already are. Even if it did turn out that you could give something that could reasonably be called a proof of such a principle, the principle would still be as evident as it ever was. Thus all mathematical reasoning depends on first principles discerned by common sense, which we believe because it is in our nature to believe them: "We are convinced by a proof, because our constitution is such, that we must be convinced by it: and we believe a self-evident axiom, because our constitution is such that we must believe it" (p. 61). Given that, we can't even properly frame the question of whether these axioms conform to the way things really are: we can't help but regard them as such because that's the way we're set up. And if you worry that we might be set up wrong, we would have to conclude that God is a deceiver, which, as Descartes notes, is problematic at best; and, moreover, that we could have no notion of truth or falsehood in the first place that doesn't depend on the way we're set up.
IIA1a. External Senses
Any evidentness that derives from the senses resolves itself into the principle that things must be as we sense them. If we did not believe this, we would think nothing obvious and evident merely because it appears so to the senses. This principle, however, and any secondary principles governing its application to particular cases, are first principles known by common sense or instinct, i.e., they are things we can't help but believe, simply because it is in our nature or constitution to believe them. If you say it is unreasonable to believe this sort of thing without proof, Beattie will answer that, since we believe it because it is in our nature to believe it, we would still be exactly as unreasonable, and for exactly the same reason, even if we did have something that we called a proof: we would believe because it is a law of our nature, not because of any proof. But what of sensory illusions and the like? Particular sensations can be fallacious, i.e., misleading; but we test sense and against sense and sensation against sensation. How do you know an optical illusion is an optical illusion? Because you use your senses to figure out that this particular sensation is misleading, the cogency of which resolves itself into the claim that things must be as we sense them, at least as a general matter. Usually when we are mistaken in these cases it is because we misattribute whether we have the evidence of sense, i.e., whether we are genuinely sensing something; but whenever we are sure we have it, we always take our conclusions to be as obvious as they can be.
IIA1b. Internal Senses
By introspection we know that we exist and have certain actions and capabilities. I know that I exist, that I remember, that I believe, that I doubt, that I feel, that I morally approve and disapprove of things. This is the evidence of internal senses, and it is as evident as anything we sense externally or know by mathematical reasoning. No proof you could give me that I do not exist or do not think could possibly be more evident than the principles that I do exist and do think; and the same can be said for any proof you could give for these principles. The principles of internal sense, like those of external sense, are known by common sense, and we cannot disbelieve them without doing violence to our nature; if there are any people who do disbelieve them, it is because they are mentally ill. And the principles of internal sense are quite important: they cover conscience and conscious reasoning alike, our sense of obligation, our sense of moral liberty, our sense of ourselves as beings that continue to exist through time (Beattie devotes a considerable amount of space to this point), and so forth. We cannot do without them. Here as with the external senses, we must accept that things must be as we sense them, not, indeed, on a point-by-point basis, but as a whole.
As with the senses, so with memory: "We trust to the evidence of memory, because we cannot help trusting it" (p. 92). Even trains of reasoning require the evidentness of memory: you need to be able to remember how you started in order to see whether you've been reasoning well. Now, it's true that we often misremember, and it's true that people remember the same event rather differently. Some (e.g., Hume) take this to indicate that the evidentness of memory is linked to its vivacity or liveliness, but Beattie denies it: our believe that something is true, or real, or exists doesn't have much to do with the liveliness of our perceptions. If we think we genuinely sense something, we are certain that it exists, regardless of how vivid the sensation is; if we think we remember something, we are certain that it happened, regardless of how vivid the memory is. Likewise with doubt, since it does not matter how vivid a sensation is, if you begin to doubt that it is a sensation (e.g., if you begin to think you are hallucinating), you begin to doubt that its object is real. It is consciousness of the fact of the memory, not the force of it, that carries the certainty.
IIA1d. Reasoning from Effect to Cause
Suppose you are in a room with a table or desk, which has nothing on it. You leave the room, and come back a little later to discover a book on the table or desk. It is a remarkable book, in terms of its binding and its color, so you are quite sure that you didn't just overlook it, and you are quite sure that you would remember it if it had been there before. We all know what question you would ask: you would ask who, or at the most extreme what, put the book there, and if someone denied that anyone put it there, you would that that is impossible. A strong word! But such is in fact the evidentness of the first principle of causal reasoning, that whatever begins to exist proceeds from a cause. It is as certain as anything else. We are all reluctant in most things to admit miracles or even Rube-Goldberg-style chains of events, but we are massively more likely to accept these things than that the book, which had not been on the table, is now on the table and that there is no cause of this whatsoever. Beattie admits that one might dispute whether this causal principle is strictly a first principle or demonstrable from some more fundamental principle (he himself doesn't think so), but this doesn't affect the certainty of it, one way or another, because in either case the ultimate reason we believe it is that it is in our nature to believe it. Hume argued that the standard arguments for the principle failed, and Beattie actually agrees with him on this point; but Hume also argued that the principle was not known intuitively because certainty only arises from the comparison of ideas in order to see their relations, and the only relations admitting of certainty were resemblance, quantitative proportions, qualitative degrees, and contrariety. Beattie rejects both premises: certainty does not arise only from the comparison of ideas, since some things are known with certainty by direct perception, and Hume's list is not exhaustive, because it cannot account for the certainty of things like personal identity. Hume also tries to argue that the principle cannot be evident because we cannot demonstrate the impossibility of its contrary; but Beattie denies that this is relevant. For some evident principles, like axioms in geometry, we cannot conceive the contrary; but for others, like 'I exist', we can. It is entirely impossible to demonstrate the impossibility of my not existing, because my existence is not necessary. But the evidentness of the principle is not any less for all of that, and the ground of it is the same: I must believe I exist, because my constitution requires it. Beattie also has an interesting discussion of causal reasoning in children, in which he argues that curiosity is a sign that the causal principle is a first principle known by instinct. We are only curious if we think there is something more than what is presented to us; but in general the reason we think there is something more than what is presented to us is causal. Curiosity, however, is certainly innate, and since it is structured causally (presented with something, we wonder why), the causal principle is innnate. To reject the causal principle as intuitively evident is to reject the idea that curiosity is part of human nature. He also goes on to argue that this shows that we can have a certain demonstration of God's existence, but, having a lot to get through, I won't dwell any more on this kind of evidence.
IIA2a. Experimental or Probable Reasoning
'Experimental reasoning' is Beattie's term for any reasoning that assumes that the course of nature will continue as it has; in short, it covers what is often called 'induction', although that word covers so many different things it seems wiser to stick with Beattie's term. 'Experimental', incidentally, doesn't mean 'having to do with experiments' but 'having to do with experience'; it is the older term for experiential, and we started calling experiments 'experiments' simply because they were kinds of manufactured experiences suitable for reasoning since they were well-defined enough to be an easy reference point. Another way Beattie will describe this kind of reasoning is as causal reasoning from causes to effects. (You will notice that previously he only talked about reasoning from effects to causes.)
We are as convinced that what has always happened will continue to happen as we are of any mathematical proof, or of the evidence of our senses. The conviction is not of the same kind. We make a distinction between moral certainty and absolute certainty, and experimental reasoning only gives you moral certainty -- probability high enough that we can treat it is certainty for most practical purposes. But it is conviction nonetheless; we are convinced that it is reasonable to presume this.. We are constantly inferring the future from the past; if the past is uniform, we get moral certainty, and if it is not, we get certainty within the limits provided by the past. This is not on the basis of any reasoning -- Beattie is in full agreement with Hume's arguments here. Beattie has some nice passages here, about a man formed fully mature on a desert island, who sees night falls for the first time, and is in distress and despair, because he has no experience on which to think the sun will ever appear again, and who, at sunrise, is in transports of joy, and he ties this with Milton's description of Adam. (Beattie is a big fan of Milton, and quotes him in illustration of points quite regularly throughout the book.)
IIA2b. Analogical Reasoning
As with experimental reasoning, so with analogical reasoning. The certainty of analogical reasoning resolves into the principle that similar causes will have similar effects, as that of experimental reasoning was of the principle that causes of the same kind will continue to have the same kind of effects, and with the necessary modifications what applies to one will apply to the other.
IIB. Faith in Testimony
There are times when not accepting what others say, makes you a fool, and everyone accepts some things without question simply because someone said so. Beattie notes that when we are dealing with honest people who tell us of what they themselves have experienced, we treat their experience exactly as if it were our own, at least for the purposes of reasoning. Thus faith in testimony is really just the evidence of external and internal senses when we have these at second-hand, and Beattie suggests that the second-handedness becomes possible through experimental principles, by which we understand that people who have been honest in the past can be presumed to be honest again. Reasoning about testimony, then, is just a specialized version of what we have already seen, and it, like all the others, resolves into first principles recognized by the instinct of common sense. Beattie, of course, knows Hume's more skeptical discussion of testimony in the Essay on Miracles, and says of it that Hume's position on the subject, like most of Hume's positions, is "directly repugnant to matter of fact" (p. 135). We are set up so as to believe testimony; this is what Scottish Common Sense philosophers often call the 'principle of credulity' ('credulity' here is not derogatory and is, I think, a quasi-technical term actually taken from Hume). Hume assumes that testimony is presumed true only when experience has shown it to be reliable. The Scottish Common Sense philosophers, most notably Reid and Campbell, had already argued at some length that the opposite is true, namely, that testimony is presumed true until experience shows it to be unreliable. A great deal of their argument has to do with children, since children do not seem to be Humean skeptics about testimony. Beattie agrees with this argument, but he does allow that there is an experience that does have some effect on our testimonial reasoning. This experience is our own experience with ourselves. Beattie notes that children tend to speak their minds, to such an extent that the uncomfortable honesty of very young children has become proverbial. This, he thinks, might increase the faith given by children in testimony. And presumably this would extend into adulthood, modulated by experience: people who are honest are at least somewhat more likely to take other people as being honest until they have reason to think. He does not, however, commit very strongly to this line of thought, and points out that whether it is true or not, the basic point stands that testimony still resolves into first principles intuitively known by common sense.
There are, then, both a priori (Part I, Chapter 1) and a posteriori (Part I, Chapter 2) reasons for thinking that common sense exists and that we know first principles by it. Beyond common sense we cannot go; and Beattie notes that, while we tend to think of it as a bad thing, there are times when it is good. A lighthouse telling you that you are at the limit of the water is exactly what you sometimes need when navigating. If all reasoning resolves into first principles known by common sense, however, then we have learned that common sense is superior to reason, and that it is common sense, not reason, that provides the standard of truth in every field of thought. Beattie notes that if this is true, then a great deal of what passes for philosophy is in fact, if taken to be serious, and not simply as a way of clarifying a matter, mere sophistry. So be it; that's what people get when they claim to provide demonstrations against what is simply obvious to everyone. Arguments showing that something non-obvious is being confused with something obvious will still be handy, of course; but refutations of first principles are topsy-turvy by nature. Likewise, things are only useful if they contribute to happiness but improving wisdom or virtue; and since attacks on first principles require people to believe contrary to nature, they can do neither and are useless. (As we shall see later, this point is actually quite important for understanding some of Beattie's later arguments.) Skeptics, of course, often hold their approach up as morally superior to that of their opponents: "for the sanguinary principles of bigotry and enthusiasm, substitute the milky ones of scepticism and moderation" (p. 144). Beattie waxes a bit sarcastic here, and in essence says that this is like a doctor trying to get a law passed that, because sick people stay at home peacefully while healthy people get into all kinds of trouble, it is now illegal to be healthy. It's true that if you eradicated conviction you would eradicate bigotry; just as there would be much less violence if you forced everyone to be sick enough to stay at home. Such remedies, however, are more troublesome than the diseases they are supposed to cure. You simply cannot eradicate conviction without doing serious damage to human beings, to the pursuit of knowledge, and to moral improvement. And to the extent that you could put such a remedy into effect, the result would only be sick and stunted minds incapable of reasoning vigorously.
To this point, Beattie is simply laying out the basic position of Scottish Common Sense philosophy, although some of his arguments are original. There are a number of questions that come to mind, though. How do we distinguish these first principles from prejudices picked up through education? Does this account have any practical value in real-life inquiry? And how would one use this foundation to respond to the skeptics Beattie is hoping to refute in this book? Some answer to these questions will be given in Part II of the Essay.