THE PHILOSOPHY OF HUME PART EIGHT

There is another problem with Hume's account of belief, one he nowhere addresses and of which he may perhaps even not have been aware. We do not believe ideas, lively or otherwise. We believe propositions. We do not believe something; we believe that something. Interestingly, the French language, with which Hume was of course completely conversant, draws this distinction quite clearly by means of the verbs savoir and connaître. "Savoir" is used when we wish to say that we know that something is the case, or that we know some fact. "Do you know that Paris is the capital of France? Yes, I know it. Oui, je le sais." But, "Do you know Paris?" [meaning, are you acquainted with Paris, have you ever been there?] "Yes, I know Paris. Oui, je le connais." Hume's simple copy theory of ideas seems not to make a place for propositional knowledge, or for our beliefs in propositional assertions. I have no idea, quite frankly, how Hume might have accommodated such assertions in his psychological account of belief.

To sum up Hume's account of our [rationally unwarranted] belief in causal inference: Experience presents us with a never-ending flow of impressions, in which we discern certain patterns -- repeated conjoinings in space and time of resembling instances. [Resemblance, let us recall, is on Hume's view a brute fact of our experience neither requiring nor having any further explanation.] These constant conjunctions trigger in us a propensity, which we bring to experience, to form habits of association. After several repetitions of such conjunctions, we come to expect the second of a pair of impressions when we are presented with the first. If the second impression is not forthcoming, we form the idea of it, which is to say a copy of one of the previously perceived instances. Furthermore, the habit we have thus formed conveys to the idea a certain amount of the force and vivacity possessed by the present impression, and the idea, thus enlivened, is believed [to exist, is what is presumably elided here]. We conceive the pair as necessarily connected, and the idea of this necessity is actually the idea of the habit or disposition thus formed and triggered. Because the propensity to form such dispositions or habits of association is one of the "permanent, irresistible and universal" propensities of the mind, without which "human nature must immediately perish and go to ruin," we neither should nor could suspend its operations. Indeed, it is all we can do for a few hours to even contemplate its abrogation. But nature can be counted on to reassert itself, and so, after a few happy hours with our friends, we find all this fussing about the justification of causal inference to be "strain'd, and ridiculous." It is for this reason that Kemp-Smith called Hume's account a theory of "natural belief."

When Hume turns to the second big topic of Book I of the Treatise, our belief in the continued and independent existence of objects, the story becomes a very great more complicated, and to my mind at least, more interesting as well. The entirety of Hume's discussion occurs in several locations in Book I, but in a desperate effort to keep this tutorial from ballooning out of all proportion, I shall confine myself to the primary discussion, in Section xiv of Part IV of Book I, "Of Scepticism With Regard to the Senses." This section is far and away the longest in Book I, running some thirty-two pages in the Selby-Bigge edition. [A mere clearing of the throat for some philosophers, but in a work by Hume, a veritable monograph.]

Before beginning my exposition and analysis, let me make a few personal remarks. I first read this section in September 1952, as a seventeen year old Sophomore in Henry David Aiken's course on Hume at Harvard. At the time, I was of course completely innocent of anything having to do with the mental development of infants, any memory of my own early development having receded into the mists of time. It was not until almost twenty years later, when I spent endless happy hours with my two baby sons, that I realized how brilliantly Hume had reconstructed the process by which the infant acquires a conception of the world. Needless to say, Hume had no such experiences on which to draw, having lived his life as a bachelor in an age when even married fathers saw little of their infant children. How on earth he got so many things right is a permanent mystery to me.

In preparation for the writing to this next portion of my tutorial, I took a few moments to review the succession of arguments in Section xiv. It has been half a century since I have done so, and the pages, somewhat yellowed into a pleasant cream color, are crisscrossed with my underlinings and marginal notations in both red and black pen. The argument is quite the most complex of any in Hume's writings, and it is, I think, important to explain it both accurately and in detail. I have decided therefore to pause before launching on this most important part of the tutorial. I shall fly to Paris tomorrow, taking with me both my copy of the Treatise and also my copies of the Enquiries and the Dialogues. After I have had time to review the argument of Section iv, I shall pick up the thread of my exposition.

While I am travelling, you may amuse yourselves by watching the first of the Fall Republican debates.

à bientôt.

CRAWLING OUT FROM UNDER ROCKS

Some of you no doubt missed the little opinion piece by Matthew Vadum which appeared yesterday on the web but is actually dated today. It is a vile attack on efforts to register poor people to vote. You can find it here: http://www.americanthinker.com/2011/09/registering_the_poor_to_vote_is_un-american.html

Here, as they say in the blogosphere, is the money quote: "Why are left-wing activist groups so keen on registering the poor to vote? Because they know the poor can be counted on to vote themselves more benefits by electing redistributionist politicians. Welfare recipients are particularly open to demagoguery and bribery. Registering them to vote is like handing out burglary tools to criminals. It is profoundly antisocial and un-American to empower the nonproductive segments of the population to destroy the country -- which is precisely why Barack Obama zealously supports registering welfare recipients to vote."

There is no need to comment on the substance of this despicable bit of right-wing rhetoric. I freely confess that it inspires in me an urge to punch this wretched twerp in the face. Views like this have been widely held for at least as long as people have been voting. What I find interesting is that it is now considered acceptable to utter them in public. I do not think this is simply an instance of what quasi-thoughtful people on the right call "epistemic closure" [which is living in an intellectually closeted world in which your most extreme thoughts are echoed back at you so reliably that they come to seem commonplace and not in need of defense.] Rather, this marks a genuine and frightening shift in the character of the public discourse.

Many of my friends blame this change on Obama, or at least charge him with being complicit in it. Others blame the Democratic Party for allowing the right to "set the agenda." I think that is far too simplistic and, in an odd way, comforting. After all, if this change is the fault of Obama or the Democratic Party in general, then all that is needed is for them to wake up and start saying all the things we want them to say, and then the "agenda" will change.

I wish that were so, because not only would it be easy enough to do, it would even be in their own political interest to do so, and therefore presumably one can count on their self-interest to produce the change. But I take a darker and more pessimistic view. If one goes back and looks, one can find countless strong statements by progressive politicians pushing back against this tidal wave of vile assaults on the poor, the non-White, on immigrants, documented or undocumented, on gays and lesbians, and on those who simply want to protect the vulnerable from life's tragedies. The failure of those statements to gain traction must be explained by something deeper.

We are living in ugly times, and those of us old enough to recall the unraveling of the Weimar Republic and the onset of Nazism find it hard to be sanguine that nothing at all like that can happen here.

THE PHILOSOPHY OF HUME PART SEVEN

[The next several parts of this tutorial will draw very heavily on the essay I published in The Philosophical Review in 1960: "Hume's Theory of Mental Activity." The entire essay has been posted on box.net and is accessible via the link top of the home page of this blog.]

The explanation Hume offers of our belief in causal inference, and also the later, much more complicated, explanation he offers of our belief in the continued and independent existence of physical objects, rests on a theory of the functioning of the human mind that he nowhere spells out clearly and explicitly. Hume fails to present his theory in explicit form, I believe, because it is in conflict with his original intention, which was to develop a theory of human nature on the model of Newton's theory of physical nature. I have already noted that Hume's account of the association of ideas is misleading, because it is not ideas that attract one another by a "gentle force" and thus become associated together, but the mind that associates the ideas one to the other. The mind is active in the process of cognition and belief. Hume does not really want to acknowledge this fact. Indeed, in Part IV, in the midst of his extraordinary and very important account of personal identity, he explicitly rejects the notion that he is offering an account of the actions of the mind. Here is the passage, from Section vi, "Of Personal Identity," in Book I, Part IV:

"The mind is a kind of theatre, where several perceptions successively make their appearance; pass, re-pass, glide away, and mingle in a infinite variety of postures and situations.... The comparison of the theatre must not mislead us. They are the successive perceptions only, that constitute the mind; nor have we the most distant notion of the place, where these scenes are represented, or of the materials, of which it is compos'd."

But this simply will not do. Without directly confronting the theory of the mind's activity on which Hume is relying, we can make no sense of any of Hume's positive accounts of our beliefs. This was obvious to me long ago, in 1956, when I w s writing my doctoral dissertation, and therefore I undertook to reconstruct from the text a systematic account of the operations of the mind as Hume presents it to us, for all that he forswears it once he has done so.

The key to Hume's "theory of mental activity," as I called it, is the notions of propensities and dispositions or habits. A disposition or habit is a settled tendency of the mind to call up a certain idea when it is presented with an impressions of a particular character. The imagination, if subjected repeatedly to the gentle force of association, develops certain habits or customs. It comes to anticipate the conjunction of perceptions which past experience has exhibited. Much as Pavlov's dog would begin to salivate at the sound of a bell, so the mind, for example, generates the idea of an "effect" if presented with the "cause." [I so hope you are all familiar with the Russian behavioral psychologist Pavlov's famous experiments with dogs. If not, Google it.]

A "propensity" can be described as the disposition to develop a disposition, or as a "second-level" disposition. When we attempt to explain the behavior of Pavlov's dog, for example, it is not enough to state that Pavlov rang the bell every time the food was offered. That is, of course, a necessary part of the explanation, but we must add that the dog was capable of being conditioned. If it were not, no amount of bell-ringing could produce the conditioned reflex of salivation. [Long experience leads me to believe that one cannot, for example, condition cats.] Let us use the term "disposition" to describe the fact that an entity is prone to act or react in certain ways under certain conditions. Let us use the term "propensity" to describe the fact that an entity is prone to develop certain dispositions under certain conditions. Then we can say that the dog's salivation upon the ringing of the bell is a manifestation of a disposition (in this case a conditioned reflex) and the disposition in turn is a manifestation of the dog's propensity (to form dispositions of this sort).

There are several simple facts about stimuli, dispositions, and propensities which it will prove helpful to keep in mind when considering Hume's theory. First, the stimuli are, of course,

sensory in nature. They are the instigators or "proximate causes" of the conditioning process, as well as the triggers of the disposition already formed. Second, the sensory stimuli are the individuating conditions of the dispositions being formed. The nature of the stimulus determines the precise character, or content, of the disposition. For example, by choosing a different stimulus, we can make the dog salivate at the blowing of a whistle or a clap of the hands rather than at the ringing of a bell. Third, dispositions are distinguished from propensities by their logical type. As mentioned above, propensities are second-level dispositions, or dispositions to form dispositions. Therefore, dispositions depend upon the conditioning stimuli and follow after them, while propensities precede both stimuli and dispositions. Propensities are thus necessary conditions for the development of dispositions.

The human mind has a small number of innate propensities, or "dispositions to form dispositions." When the mind is presented with perceptions conjoined in certain ways, its propensities are activated and it develops dispositions. These dispositions determine the mind to reproduce in imagination certain impressions when it experiences certain others. [The mind, of course, reproduces them as ideas, less vivid than the impressions of which they are copies.] The mind, in another of Hume's phrases, forms a "habit of association." The factors in cognition which Hume labeled impressions of reflection -- such as the impression of necessary connection, as we shall see in a moment -- are really dispositions, and the ideas of necessary connection, substance, and so forth, are not copies of impressions but ideas of mental dispositions. The innate propensities constitute the basic "machinery" of the mind. They are the necessary and universal conditions of all our ideas of causes and objects. In Hume's words:

"In order to justify myself, I must distinguish in the imagination betwixt the principles which are permanent, irresistible, and universal; such as the customary transition from causes to effects, and from effects to causes: And the principles, which are changeable, weak, and irregular; such as those I have just now taken notice of. The former are the foundation of all our thoughts and actions, so that upon their removal human nature must immediately perish and go to ruin."

With these few notions before us, we can now make a good deal of sense of Hume's explanation of our tendency to form causal inferences and to believe in their results. When we examine specific causal reasoning, Hume tells us, we find four components: an impression, an inference, an idea, and a belief. All causal reasoning begins with an impression of sensation which is present before the mind and acts as the anchor of the entire process. The second component is the inference by which the mind passes from the present impression to an idea. This idea, related to the impression, is the third component of the reasoning process. Fourth, there is the belief which we then repose in the idea.

The impression needs no explanation. To account for the inference to the idea, Hume introduces the factor of "constant conjunction." Upon examining causally related objects, and reflecting back over past experience, we discover that whenever we label one object cause of another, we can recall pairs of contiguous and successive objects which resemble the present impression

and idea. As the objects appear again and again in similar relations to one another, they become "associated" in the imagination. By a natural mental process, the habit is inculcated of conceiving of the one when the other is perceived. When the impression of the cause, let us say, is present to the mind, then the disposition created by past conjunction determines the mind to

reproduce the idea of the effect. The essence of the causal inference lies in this transition. There remains only the belief, which I shall come to presently.

Hume returns in Section 14 of Part iii to the first question, What is the nature of the idea of necessary connection? His analysis of particular causal inferences has produced three conclusions which, he believes, permit him now to answer the question. The conclusions are:

"[T]hat the simple view of any two objects or actions, however related, can never give us any idea of power, or of a connexion betwixt them: that this idea arises from the repetition of their union: that the repetition neither discovers nor causes any thing in the objects, but has an influence only on the mind, by that customary transition it produces."

But every idea, says Hume, is a copy of some preceding impression. As the idea of necessary connection is not derived from any quality or relation of objects, it cannot be a copy of an impression of sensation, so it must be an impression of reflection, that being the only other kind, according to Hume. The only available impression of reflection is the "feeling" attached to the disposition of the mind to pass from an object to the idea associated with it. Therefore the idea of necessary connection must be the idea of this mental transition.

This analysis of causal inference depends on three points, each of which requires some comment. The points are: (i) the nature of the "transition" from impression to related idea; (2) the nature

of the "impression of necessary connexion" on which we base our idea of causal influence; and (3) the nature of the mechanism of belief, whereby we assent to the inference and take the associated idea as objectively representative. Let us consider them in turn. The "transition" of which Hume speaks is not to be understood as a passing of the mind from one present perception to another present perception. What happens is that the mind, perceiving the first, "forms an idea of its usual attendant" (p. 93). In other words, the mind reproduces in imagination a copy of the impression which has lately been associated with the present impression. This process of recall is the manifestation of a mental disposition or "habit" which is inculcated by experience. The mind is confronted with a succession of resembling impressions, and thereupon develops a disposition to conceive the one when it perceives the other. As I have already noted, the proneness of the mind to develop such a disposition is itself a disposition; it is what I called a "propensity." Hume now sets to one side the aspects of causal reasoning which are independent of the mind's inferences. The contiguity and succession of objects is indeed separate from our

thought, as is the constant association of like objects. That is simply part of which is given to us in experience, and requires no further explanation. These relations are "independent of, and antecedent to the operations of the understanding," as Hume puts it. But the necessity of

their connection is a property of our inference upon them and derives from the mind's "habit." In the terminology which I have adopted, the associated impressions act as stimuli to activate an

innate propensity; the result is a mental disposition to imagine a related idea when presented with an impression.

This is all a bit gnarly, so let me recapitulate in a few words. We observe repeated cases in which similar pairs of sense impressions occur right next to one another in space and time. Fire-heat, fire-heat, fire-heat. The mind has an innate propensity to develop a habit of associating such constantly conjoined pairs, so that when I observe one of them but not the other, I conjure up an idea of the missing one. [I see a fire, but do not feel heat. This triggers the habit of association, and I call up the idea of heat, thinking to myself, "I bet that fire is hot."]

The second element of Hume's analysis is the "impression of necessary connexion" from which the idea of causal influence is copied. We are here presented with a common problem of textual

interpretation. What Hume says is not the same as what Hume says he says. The natural development of his argument leads him in one direction, but the prior strictures of his system require a different and conflicting move. Hume talks as if the impression of necessary connection, like an impression of love or envy, were a directly observable mental content arising

from the workings of the imagination. But the description which he actually gives of this impression is peculiar, to say the least.

The "internal impression," he claims, is the "propensity, which custom produces, to pass from an object to the idea of its usual attendant." Again, the "customary transition is the same with the power and necessity." Hume is not saying here that the impression arises from the transition or is conjoined with the transition or is dependent upon the transition. He is saying that the impression is the transition. Now this is plainly an error in classification. It is what in the 1950's and 60's we used to call a "category mistake," following Gilbert Ryle's usage of that phrase in his very influential book The Concept of Mind. [Full disclosure: I wrote my undergraduate honors thesis on that book in 1953, and out of it managed to get my very first professional publication, a little note in MIND, a tasty bit with the enticing title "Professor Ryle's Discussion of Agitations."]

"Customary transitions" and "propensities" are mental operations or powers, not contents of consciousness. If the idea of necessary connection is a copy of the transition from an impression to its usual attendant, then it is a copy of a mental activity. It is in fact the idea of the mind's disposition to reproduce related perceptions in imagination. In these passages we can observe Hume shifting toward explanation in terms of mental activities, while still tied to the language of mental contents. Later on we shall see him move even further in this direction when he deals with the problem of external objects.

Finally, there is the problem of belief. Hume rejects the scholastic view that to believe in the existence of an object is to conjoin an idea of existence to the idea of the object. He casts about, therefore, for some quality common to all the ideas and impressions in which we repose belief, and he hits upon "the manner of our conceiving them." The belief in an idea is nothing but an increased force and vivacity by which our conception is heightened and enlivened." This theory, as Hume himself recognized, is open to serious objections. One objection is the fact that there are many common beliefs which cannot be explained as "enlivened ideas." When we form an inference upon the evidence of historical traces, and reason from a present impression of manuscripts to the past existence of a historical personage, the resultant belief cannot be attributed to the force of the impressions of the text before us. We could not, for example,

strengthen the belief by illuminating the page more brightly or recasting the print more sharply. Hume appears to take account of this objection in several passages, the first of which contains a

turn of phrase suggesting a possible revision:

"For suppose I form at present an idea, of which I have forgot the correspondent impression, I am able to conclude from this idea, that such an impression did once exist; and as this conclusion is attended with belief, it may be ask'd, from whence are the qualities of force and vivacity deriv'd, which constitute this belief? And to this I answer very readily, from the present idea. For as this idea is not here considered as the representation of any absent object, but as a real perception in the mind, of which we are intimately conscious, it must be able to bestow on whatever is related to it the same quality, call it firmness, or solidity, or force, or vivacity with which the mind reflects upon it, and is assur'd of its present existence."

The key phrase is the last clause but one of the final sentence. The present idea, serving as the "impression" from which the inference proceeds, must possess that firmness or solidity or force

or vivacity with which the mind reflects upon it. The force is not a quality of the perception, but rather a quality of the way in which the mind conceives it. Hence any idea or impression, however weak, may serve as the starting point for a causal inference, if only the mind reflects upon it with the solidity of belief. Now in the passage I have quoted, Hume uses this locution only to explain our inference from a present idea to the past impression of which it is a copy. But in the Appendix to the Treatise, he extends the same description to all belief. There he states that the "feeling" of belief is a "firmer conception, or a faster hold, that we take of the object." Belief is not a hold that the object takes on us, but that we take on the object. Here again we see a shift in emphasis from the characteristics of perception to some activity of the mind.

THE PHILOSOPHY OF HUME -- A PROBLEM

As I anticipated, I have arrived at a problem that I am not sure how to solve. The next several posts of this tutorial are intended to explain and expound the central doctrines of Book I, Parts III [causation] and IV [our belief in the continued and independent existence of objects.] Half a century and more, I published an essay in which I discussed these matters, and all this time later, I do not think I can do it any better than I did there. The essay, "Hume's Theory of Mental Activity," is posted on box.net, where, at this point, it has been previewed or downloaded seventy-eight times. I really do not want to try to re-write what I wrote successfully [or so I believe] in 1960, so the natural solution is to insert lengthy excerpts from the essay in this tutorial. But that will be terminally boring to those faithful readers who have in fact followed my exhortations and looked at the 1960 essay.



Meanwhile, Susie and I are preparing to go to Paris on Tuesday, so I am engaged with last-minute preparations. What to do?



I think I will take a break at this point, meditate on my options, and return to the tutorial once I have arrived in Paris. In the interim, I may post a comment or two on the passing scene, but think of this as a Labor Day suspension of classes.

THE PHILOSOPHY OF HUME PART SIX

The entire refutation of the principle of Cause and Effect is contained in a single paragraph in Section III of Part II of Book I. Hume considers the "general maxim in philosophy," that "whatever begins to exist, must have a cause of existence." I think he is justified in claiming that all of traditional metaphysics, theology, and natural science rests on this principle. Here is the paragraph, from start to finish:

"But here is an argument, which proves at once, that the foregoing proposition is neither intuitively nor demonstratively certain. We can never demonstrate the necessity of a cause for every new existence, or new modification of existence, without shewing at the same time the impossibility there is, that any thing can ever begin to exist without some productive principle: and where the latter proposition cannot be prov'd, we must despair of ever being able to prove the former. Now that the latter proposition is utterly incapable of a demonstrative proof, we may satisfy ourselves by considering, that as all distinct ideas are separable from each other, and as the ideas of cause and effect are evidently distinct, 'twill be easy for us to conceive any object to be non-existent this moment, and existent the next, without conjoining to it the distinct idea of a cause or productive principle. The separation, therefore, of the idea of a cause from that of a beginning of existence, is plainly possible for the imagination; and consequently the actual separation of these objects is so far possible, that it implies no contradiction nor absurdity; and is therefore incapable of being refuted by any reasoning from mere ideas; without which 'tis impossible to demonstrate the necessity of a cause."

And with those two hundred and thirteen words, Hume puts paid to all previous philosophy and science. It is not surprising that Kant was, as he said, awakened from his dogmatic slumbers by this savage attack. There were, in the tradition, a number of silly arguments [put forward by some very serious people] in support of the Causal Maxim, and Hume has a bit of fun batting them away. One is that if something does not have a cause, then it must have produced itself, which is impossible [save for God, of course]. Another is that if something does not have a cause, then it must have been produced by nothing, and as we know [although Hume does not add this], ex nihilo nihil fit. " 'Tis sufficient to observe," Hume replies, "that when we exclude all causes we really do exclude them, and neither suppose nothing nor the object itself to be the causes of existence." These arguments actually are good examples of that oft-misused phrase, "begging the question."

There is another possible objection that Hume does not discuss at this point in the text, though he does elsewhere. It might be said that science does not assert absolute necessities, but only probabilities, that scientific reasoning is inductive, not deductive, and hence that Hume's refutation, though certainly telling against anyone who is so unwise as to assert causal judgments in the explanation of nature with the absolute certainty of logic, leaves quite untouched the sorts of scientific explanations that appeal to well-confirmed generalizations, for all that they may fall short of the certainty of syllogistic reasoning. The difficulty with this defense of causal inference, as Hume quite well understands, and as I think we all now recognize, is that it rests on the equally indemonstrable assumption of the Uniformity of Nature. All causal reasoning, Hume will argue in the sections following the present one, takes the form of observing patterns in our experience and then projecting them forward in time or outward in space, leading us to conclude that the portions of the world we have not observed are, in the relevant ways, like the portions we have observed. But induction from present instances to conclusions about the world in general is no better grounded than deduction. Since it is quite easy to imagine that some region of space or time not yet encountered should exhibit different patterns from those already experienced, it "is so far possible, that it implies no contradiction nor absurdity." There simply is no rational ground, Hume insists, for the beliefs that constitute the warp and woof of our conception of the world in which we live.

As often happens in our reading of Hume, his most powerful arguments go by so quickly, with so little sign of stress and strain and heavy lifting, that it is easy for us to overlook just how devastating they are. If Hume is correct, then entire libraries of ancient, medieval, and early modern philosophy must simply be discarded, along with the revolutionary natural science of Galileo, Kepler, Newton, and their contemporaries, not to speak of the corpus of Hebrew, Muslim, and Christian rational theology that was the glory of the Middle Ages. Those of you who followed my Introduction to the Critique of Pure Reason can now see, I think, why Kant concluded that a reply to Hume required the heroic embrace of the proposition that the entire experienced world is merely things as they appear to us, rather than things as they are in themselves.

And yet. And yet. We do believe. No normal, sane, functioning person can actually go through life not believing that events have causes. One cannot even play a game of billiards unless one believes that the striking of one ball by a second causes the first to move. So Hume now pivots from his sceptical attack on the claims of philosophers and scientists, and undertakes to explain our belief in causal judgments, using in his explanations a variety of causal judgments about the workings of the mind and its responses to experience. Norman Kemp-Smith, in his classic 1941 study The Philosophy of David Hume, describes Hume as advancing a theory of "natural belief." It is essentially a psychological account of how beliefs are generated in us, and Hume is quite clear that this account is not intended somehow to invalidate the previous sceptical line of attack. As we shall see, most of the original and exciting doctrines of Book I of the Treatise concern the ways in which the mind constructs a conception of a world of causally connected objects. It was this account, when I first encountered it, that reminded me so powerfully of the theory of a priori synthesis in Kant's First Critique.

In the very last section of Book I, some 190 pages beyond the passages we have just been discussing, Hume writes a passage that is, to my ear, poignant and very touching. Having raised powerful and telling objections to all of the principles on which previous philosophy and science rested, Hume draws back from the abyss he has himself opened up.

"Most fortunately it happens," he says, "that since reason is incapable of dispelling these clouds, nature herself suffices to that purpose, and cures me of this philosophical melancholy and delirium, either by relaxing this bent of mind, or by some avocation, and lively impression of my senses, which obliterate all these chimeras. I dine, I play a game of back-gammon, I converse, and am merry with my friends; and when after three or four hours' amusement, I wou'd return to these speculations, they appear so cold, so strain'd. and ridiculous, that I cannot find in my heart to enter into them any farther."

THE PHILOSOPHY OF HUME PART FIVE

In Part III of Book I, entitled "Of Knowledge and Probability," Hume proceeds in a rather curious and idiosyncratic manner that will strike modern readers especially as very odd. Later on, we shall see that when he came to write the Enquiry Concerning the Human Understanding, he shifted to a mode of analysis that is much more in keeping with the discussions of analytic and synthetic judgments that were common in the early and middle twentieth century, and which derive in large measure from Kant. Indeed, this change is one of the two principal ways in which the doctrine of the Enquiry differs from that of the Treatise.

Let us keep in mind that Hume has only three elements to his analysis of "human nature": the diversity of perceptions that present themselves in consciousness; relations of one sort or another among those perceptions; and the habits and propensities of the mind to do something or other with those perceptions. Everything must be explained in terms of these three elements. Part I contains Hume's account of the perceptions [impressions and ideas, simple and complex, impressions of sensation and impressions of reflexion] and a preliminary description of the "gentle force" of association. Part III now examines the relations that perceptions bear to one another.

Hume identifies seven kinds of what he calls "philosophical relation," namely: resemblance, identity, relations of time and place, proportions in quantity or number, degrees in any quality, contrariety, and causation. He now divides these into those relations that "depend entirely on the ideas," and those that can be changed by a change in the order or manner in which they are presented to the mind. According to Hume, resemblance, contrariety, degrees in quality, and proportions in quantity or number are of the first sort. Regardless of the order or manner in which ideas present themselves to the mind, these four relations remain unaltered. Hence, Hume says, they and they alone can yield genuine knowledge. The other three, namely identity, relations of time and place, and most especially causation, can be altered, without any change in the ideas themselves, merely by the order or manner in which they appear to us.

This is [at least to me] an unexpected way of classifying relations, and it is worth taking a moment to be clear about what Hume is saying. Whether two ideas resemble one another [say, two shades of a color, or two human faces] is, he says, purely a function of the unalterable characteristics of the ideas, and is immediately apparent to us without any process of reasoning into which we could introduce doubt. Either two ideas strike us as resembling or they do not, regardless of whether A appears before or after B, or appears near to or far from B, or appears quite contemporaneously to B or separated by a lengthy period of time. The same is true for the relation of contrariety [which seems to be simply the negative of resemblance], and also relations of quantity and quality. Hume has no quarrel with anyone who wishes to claim that judgments of resemblance, contrariety, quality, and quantity can yield certainty and hence genuine knowledge, and almost immediately he leaves them behind, never to trouble with them again. It is the other three -- identity, time and place, and causation, and especially identity and causation, on which he will spend the next 200 pages.

As many modern readers of the Treatise have pointed out, Hume is in fact wrong about the group of four relations that are supposedly invariant under changes in the manner of presentation. All of us these days are familiar, as Hume was not, with so-called gestalt phenomena. Surround two identically matching dots of color with expanses of differing colors, and they no longer look identical. Draw a pair of manifestly parallel lines, append to them rows of little slanting appendages tilted in different directions, and they cease to look parallel. These facts do not really very much call Hume's arguments about identity and causation into question, but they are interesting, and suggest that the facts of perception are more complex than Hume supposed.

Hume now turns his attention to the idea of cause and effect, and immediately things get very interesting indeed. He begins [Section II] by noting something that is central to his epistemology. Of all seven relations, only causation carries me beyond the evidence of the senses, to objects and events not now present to me. To remain with his examples, I feel a great heat, and infer the existence of a fire, even though I do not now see a fire. I hear the sound of footsteps, and infer that someone is climbing the stairs to my apartment, even though no person is at this moment before my eyes. Hume is poignantly aware of the fact that our actual sense presentations are a thin and radically incomplete fragment of the world in which we imagine ourselves to be living. We are trapped in the subjectivity of consciousness, and only causal inference carries us beyond immediate presentations, fleshing them out with people and objects, with a world. The same is true with regard to time. What I perceive at any moment is a tiny slice of the temporal flow of perceptions that taken all together constitute my consciousness. Only causal inference enables us to infer past events from present perceptions. Hume's starting point is what came in later centuries to be called a "solipsism of the present moment."

For this reason, it is for Hume a matter of the greatest urgency to examine causal inference and determine two things: First, whether causal inference can be justified by any process of reasoning; and Second, if it cannot, how and why it is that despite the lack of the slightest rational justification, we firmly believe the causal inferences we make, and ground our entire lives upon them.

With the examination of the idea of causal connexion, Hume embarks on the core reasoning of Book I of the Treatise. For the first time, we see the enormous power of the elementary claim, advanced at the very start of Book I, that all of our ideas are copies of preceding impressions. If we are to understand the idea of causation, he says, we must "trac[e] it up to its origin, and examin[e] that primary impression from which it arises." This is the defining rhetorical and analytical move of the British Empiricist school, brought to its highest pitch by Hume. "Hunt the impression!" might be the motto inscribed on the banner under which Hume rides into battle.

When we cast about for examples of causes and effects -- or rather, for examples of what are commonly considered causes and effects -- we find that the idea cause does not arise from the properties of any particular object or event. Rather, it arises, Hume says, from pairs of resembling instances of objects or events that exhibit two characteristics: they are spatially contiguous and they are temporally continuous. Hume is here echoing the common scientific conviction of his day that there cannot be what was called "action at a distance." If one event causes a second, then the first must occur immediately before the second and in immediate proximity to it. If there is the least lapse of time between cause and effect, or the least spatial gap between the two, then we may be sure that there is some intervening event that is the effect of the first and the cause of the second.

But contiguity and continuity alone are not sufficient to yield the idea of causal connexion, for post hoc ergo propter hoc is a fallacy of reasoning, not a foundational principle. There is one more essential component of the idea of causation: necessity of connexion. [I realize that I have fallen into the habit of using Hume's spelling -- you will have to be patient with me, as I wander down memory lane.] Hume now poses two questions, quite different from one another, which must both be answered before we are done with the matter of causation:

"First, for what reason we pronounce it necessary, that every thing whose existence has a beginning, shou'd also have a cause? Secondly, Why we conclude that such particular causes must necessarily have such particular effects; and what is the nature of the inference we draw from the one to the other, and of the belief we repose in it?"

Tomorrow, we shall examine the most famous and consequential sceptical argument in the history of philosophy.

FAME COMES TO THE OLD PHILOSOPHER, LATE IN LIFE

High Arka, who hides behind an impenetrable webname while hurling thunderbolts from his elevated position of permanent high dudgeon, refers to me on his own website as "Death Lord Wolff." Ignorant as I am of the world of computer games, I mistakenly thought that I was being compared to Darth Vader, whose voice of course was that of the great actor James Earl Jones. Momentarily I was quite thrilled by the comparison. But Wikipedia informs me that DeathLord is simply a character in a computer game, which seems rather a comedown. Oh well.



In the extended rant to which he links, High Arka sneers disdainfully at my efforts to provide university educations to some young South Africans. It must be wonderfully relaxing to see every act in the world as just another contemptible example of, as he/she says,

African Orientalism. One need therefore never actually do anything at all, inasmuch as anything one might try to do is fatally infected with objective and subjective bad motives and consequences. So one can, with considerable self-congratulation, remain completely, comfortably inert.



It is difficult to have a genuine conversation with someone who is unwilling to reveal him/herself, so instead I offer a bargain to High Arka: I will stay off your blog, if you stay off mine.