They not only have no character in common, but it is inconceivable that they should have any. On the a.s.sumption, that the attributes of the two were wholly different, it appeared to be a necessary consequence that the hypothetical causes of these attributes--their respective substances--must be totally different. Notably, in the matter of divisibility, since that which has no extension cannot be divisible, it seemed that the _chose pensante_, the soul, must be an indivisible ent.i.ty.
Later philosophers, accepting this notion of the soul, were naturally much perplexed to understand how, if matter and spirit had nothing in common, they could act and react on one another. All the changes of matter being modes of motion, the difficulty of understanding how a moving extended material body was to affect a thinking thing which had no dimension, was as great as that involved in solving the problem of how to hit a nominative case with a stick. Hence, the successors of Descartes either found themselves obliged, with the Occasionalists, to call in the aid of the Deity, who was supposed to be a sort of go-between betwixt matter and spirit; or they had recourse, with Leibnitz, to the doctrine of pre-established harmony, which denied any influence of the body on the soul, or _vice versa_, and compared matter and spirit to two clocks so accurately regulated to keep time with one another, that the one struck when ever the other pointed to the hour; or, with Berkeley, they abolished the "substance" of matter altogether, as a superfluity, though they failed to see that the same arguments equally justified the abolition of soul as another superfluity, and the reduction of the universe to a series of events or phenomena; or, finally, with Spinoza, to whom Berkeley makes a perilously close approach, they a.s.serted the existence of only one substance, with two chief attributes, the one, thought, and the other, extension.
There remained only one possible position, which, had it been taken up earlier, might have saved an immensity of trouble; and that was to affirm that we do not, and cannot, know anything about the "substance"
either of the thinking thing, or of the extended thing. And Hume"s sound common sense led him to defend this thesis, which Locke had already foreshadowed, with respect to the question of the substance of the soul.
Hume enunciates two opinions. The first is that the question itself is unintelligible, and therefore cannot receive any answer; the second is that the popular doctrine respecting the immateriality, simplicity, and indivisibility of a thinking substance is a "true atheism, and will serve to justify all those sentiments for which Spinoza is so universally infamous."
In support of the first opinion, Hume points out that it is impossible to attach any definite meaning to the word "substance" when employed for the hypothetical substratum of soul and matter. For if we define substance as that which may exist by itself, the definition does not distinguish the soul from perceptions. It is perfectly easy to conceive that states of consciousness are self-subsistent. And, if the substance of the soul is defined as that in which perceptions inhere, what is meant by the inherence? Is such inherence conceivable? If conceivable, what evidence is there of it? And what is the use of a substratum to things which, for anything we know to the contrary, are capable of existing by themselves?
Moreover, it may be added, supposing the soul has a substance, how do we know that it is different from the substance, which, on like grounds, must be supposed to underlie the qualities of matter?
Again, if it be said that our personal ident.i.ty requires the a.s.sumption of a substance which remains the same while the accidents of perception shift and change, the question arises what is meant by personal ident.i.ty?
"For my part," says Hume, "when I enter most intimately into what I call _myself_, I always stumble on some particular perception or other, of heat or cold, light or shade, love or hatred, pain or pleasure. I never can catch _myself_ at any time without a perception, and never can observe anything but the perception. When my perceptions are removed for any time, as by sound sleep, so long am I insensible of _myself_, and may be truly said not to exist.
And were all my perceptions removed by death, and I could neither think, nor feel, nor see, nor love, nor hate, after the dissolution of my body, I should be entirely annihilated, nor do I conceive what is further requisite to make me a perfect nonent.i.ty. If any one, upon serious and unprejudiced reflection, thinks he has a different notion of _himself_, I must confess I can reason no longer with him. All I can allow him is, that he may be in the right as well as I, and that we are essentially different in this particular. He may perhaps perceive something simple and continued which he calls _himself_, though I am certain there is no such principle in me.
"But setting aside some metaphysicians of this kind, I may venture to affirm of the rest of mankind, that they are nothing but a bundle or collection of different perceptions, which succeed one another with an inconceivable rapidity, and are in a perpetual flux and movement.... The mind is a kind of theatre, where several perceptions successively make their appearance, pa.s.s, repa.s.s, glide away, and mingle in an infinite variety of postures and situations.
There is properly no _simplicity_ in it at one time, nor _ident.i.ty_ in different, whatever natural propension we may have to imagine that simplicity and ident.i.ty. The comparison of the theatre must not mislead us. They are the successive perceptions only that const.i.tute 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 composed.
"What then gives so great a propension to ascribe an ident.i.ty to these successive perceptions, and to suppose ourselves possessed of an invariable and uninterrupted existence through the whole course of our lives? In order to answer this question, we must distinguish between personal ident.i.ty as it regards our thought and imagination, and as it regards our pa.s.sions, or the concern we take in ourselves. The first is our present subject; and to explain it perfectly we must take the matter pretty deep, and account for that ident.i.ty which we attribute to plants and animals; there being a great a.n.a.logy betwixt it and the ident.i.ty of a self or person."--(I. pp. 321, 322.)
Perfect ident.i.ty is exhibited by an object which remains unchanged throughout a certain time; perfect diversity is seen in two or more objects which are separated by intervals of s.p.a.ce and periods of time.
But, in both these cases, there is no sharp line of demarcation between ident.i.ty and diversity, and it is impossible to say when an object ceases to be one and becomes two.
When a sea-anemone multiplies by division, there is a time during which it is said to be one animal partially divided; but, after a while, it becomes two animals adherent together, and the limit between these conditions is purely arbitrary. So in mineralogy, a crystal of a definite chemical composition may have its substance replaced, particle by particle, by another chemical compound. When does it lose its primitive ident.i.ty and become a new thing?
Again, a plant or an animal, in the course of its existence, from the condition of an egg or seed to the end of life, remains the same neither in form, nor in structure, nor in the matter of which it is composed: every attribute it possesses is constantly changing, and yet we say that it is always one and the same individual. And if, in this case, we attribute ident.i.ty without supposing an indivisible immaterial something to underlie and condition that ident.i.ty, why should we need the supposition in the case of that succession of changeful phenomena we call the mind?
In fact, we ascribe ident.i.ty to an individual plant or animal, simply because there has been no moment of time at which we could observe any division of it into parts separated by time or s.p.a.ce. Every experience we have of it is as one thing and not as two; and we sum up our experiences in the ascription of ident.i.ty, although we know quite well that, strictly speaking, it has not been the same for any two moments.
So with the mind. Our perceptions flow in even succession; the impressions of the present moment are inextricably mixed up with the memories of yesterday and the expectations of to-morrow, and all are connected by the links of cause and effect.
" ... as the same individual republic may not only change its members, but also its laws and const.i.tutions; in like manner the same person may vary his character and disposition, as well as his impressions and ideas, without losing his ident.i.ty. Whatever changes he endures, his several parts are still connected by the relation of causation. And in this view our ident.i.ty with regard to the pa.s.sions serves to corroborate that with regard to the imagination, by the making our distant perceptions influence each other, and by giving us a present concern for our past or future pains or pleasures.
"As memory alone acquaints us with the continuance and extent of this succession of perceptions, "tis to be considered, upon that account chiefly, as the source of personal ident.i.ty. Had we no memory we never should have any notion of causation, nor consequently of that chain of causes and effects which const.i.tute our self or person. But having once acquired this notion of causation from the memory, we can extend the same chain of causes, and consequently the ident.i.ty of our persons, beyond our memory, and can comprehend times, and circ.u.mstances, and actions, which we have entirely forgot, but suppose in general to have existed. For how few of our past actions are there of which we have any memory?
Who can tell me, for instance, what were his thoughts and actions on the first of January, 1715, the eleventh of March, 1719, and the third of August, 1733? Or will he affirm, because he has entirely forgot the incidents of those days, that the present self is not the same person with the self of that time, and by that means overturn all the most established notions of personal ident.i.ty? In this view, therefore, memory does not so much _produce_ as _discover_ personal ident.i.ty, by showing us the relation of cause and effect among our different perceptions. "Twill be inc.u.mbent on those who affirm that memory produces entirely our personal ident.i.ty, to give a reason why we can thus extend our ident.i.ty beyond our memory.
"The whole of this doctrine leads us to a conclusion which is of great importance in the present affair, viz. that all the nice and subtle questions concerning personal ident.i.ty can never possibly be decided, and are to be regarded rather as grammatical than as philosophical difficulties. Ident.i.ty depends on the relations of ideas, and these relations produce ident.i.ty by means of that easy transition they occasion. But as the relations, and the easiness of the transition may diminish by insensible degrees, we have no just standard by which we can decide any dispute concerning the time when they acquire or lose a t.i.tle to the name of ident.i.ty. All the disputes concerning the ident.i.ty of connected objects are merely verbal, except so far as the relation of parts gives rise to some fiction or imaginary principle of union, as we have already observed.
"What I have said concerning the first origin and uncertainty of our notion of ident.i.ty, as applied to the human mind may be extended, with little or no variation, to that of _simplicity_. An object, whose different co-existent parts are bound together by a close relation, operates upon the imagination after much the same manner as one perfectly simple and undivisible, and requires not a much greater stretch of thought in order to its conception. From this similarity of operation we attribute a simplicity to it, and feign a principle of union as the support of this simplicity, and the centre of all the different parts and qualities of the object."--(I. pp. 331-3.)
The final result of Hume"s reasoning comes to this: As we use the name of body for the sum of the phenomena which make up our corporeal existence, so we employ the name of soul for the sum of the phenomena which const.i.tute our mental existence; and we have no more reason, in the latter case, than in the former, to suppose that there is anything beyond the phenomena which answers to the name. In the case of the soul, as in that of the body, the idea of substance is a mere fiction of the imagination. This conclusion is nothing but a rigorous application of Berkeley"s reasoning concerning matter to mind, and it is fully adopted by Kant.[35]
Having arrived at the conclusion that the conception of a soul, as a substantive thing, is a mere figment of the imagination; and that, whether it exists or not, we can by no possibility know anything about it, the inquiry as to the durability of the soul may seem superfluous.
Nevertheless, there is still a sense in which, even under these conditions, such an inquiry is justifiable. Leaving aside the problem of the substance of the soul, and taking the word "soul" simply as a name for the series of mental phenomena which make up an individual mind; it remains open to us to ask, whether that series commenced with, or before, the series of phenomena which const.i.tute the corresponding individual body; and whether it terminates with the end of the corporeal series, or goes on after the existence of the body has ended. And, in both cases, there arises the further question, whether the excess of duration of the mental series over that of the body, is finite or infinite.
Hume has discussed some of these questions in the remarkable essay _On the Immortality of the Soul_, which was not published till after his death, and which seems long to have remained but little known.
Nevertheless, indeed, possibly, for that reason, its influence has been manifested in unexpected quarters, and its main arguments have been adduced by archiepiscopal and episcopal authority in evidence of the value of revelation. Dr. Whately,[36] sometime Archbishop of Dublin, paraphrases Hume, though he forgets to cite him; and Bishop Courtenay"s elaborate work,[37] dedicated to the Archbishop, is a development of that prelate"s version of Hume"s essay.
This little paper occupies only some ten pages, but it is not wonderful that it attracted an acute logician like Whately, for it is a model of clear and vigorous statement. The argument hardly admits of condensation, so that I must let Hume speak for himself:--
"By the mere light of reason it seems difficult to prove the immortality of the soul: the arguments for it are commonly derived either from metaphysical topics, or moral, or physical. But in reality it is the gospel, and the gospel alone, that has brought _life and immortality_ to light.[38]
"1. Metaphysical topics suppose that the soul is immaterial, and that "tis impossible for thought to belong to a material substance.[39] But just metaphysics teach us that the notion of substance is wholly confused and imperfect; and that we have no other idea of any substance, than as an aggregate of particular qualities inhering in an unknown something. Matter, therefore, and spirit, are at bottom equally unknown, and we cannot determine what qualities inhere in the one or in the other.[40] They likewise teach us, that nothing can be decided _a priori_ concerning any cause or effect; and that experience, being the only source of our judgments of this nature, we cannot know from any other principle, whether matter, by its structure or arrangement, may not be the cause of thought. Abstract reasonings cannot decide any question of fact or existence. But admitting a spiritual substance to be dispersed throughout the universe, like the ethereal fire of the Stoics, and to be the only inherent subject of thought, we have reason to conclude from _a.n.a.logy_, that nature uses it after the manner she does the other substance, _matter_. She employs it as a kind of paste or clay; modifies it into a variety of forms or existences; dissolves after a time each modification, and from its substance erects a new form. As the same material substance may successively compose the bodies of all animals, the same spiritual substance may compose their minds: Their consciousness, or that system of thought which they formed during life, may be continually dissolved by death, and nothing interests them in the new modification. The most positive a.s.sertors of the mortality of the soul never denied the immortality of its substance; and that an immaterial substance, as well as a material, may lose its memory or consciousness, appears in part from experience, if the soul be immaterial. Seasoning from the common course of nature, and without supposing any new interposition of the Supreme Cause, which ought always to be excluded from philosophy, _what is incorruptible must also be ingenerable_. The soul, therefore, if immortal, existed before our birth, and if the former existence noways concerned us, neither will the latter. Animals undoubtedly feel, think, love, hate, will, and even reason, though in a more imperfect manner than men: Are their souls also immaterial and immortal?"[41]
Hume next proceeds to consider the moral arguments, and chiefly
" ... those derived from the justice of G.o.d, which is supposed to be further interested in the future punishment of the vicious and reward of the virtuous."
But if by the justice of G.o.d we moan the same attribute which we call justice in ourselves, then why should either reward or punishment be extended beyond this life?[42] Our sole means of knowing anything is the reasoning faculty which G.o.d has given us; and that reasoning faculty not only denies us any conception of a future state, but fails to furnish a single valid argument in favour of the belief that the mind will endure after the dissolution of the body.
" ... If any purpose of nature be clear, we may affirm that the whole scope and intention of man"s creation, so far as we can judge by natural reason, is limited to the present life."
To the argument that the powers of man are so much greater than the needs of this life require, that they suggest a future scene in which they can be employed, Hume replies:--
"If the reason of man gives him great superiority above other animals, his necessities are proportionably multiplied upon him; his whole time, his whole capacity, activity, courage, and pa.s.sion, find sufficient employment in fencing against the miseries of his present condition; and frequently, nay, almost always, are too slender for the business a.s.signed them. A pair of shoes, perhaps, was never yet wrought to the highest degree of perfection that commodity is capable of attaining; yet it is necessary, at least very useful, that there should be some politicians and moralists, even some geometers, poets and philosophers, among mankind. The powers of men are no more superior to their wants, considered merely in this life, than those of foxes and hares are, compared to _their_ wants and to their period of existence. The inference from parity of reason is therefore obvious."
In short, Hume argues that, if the faculties with which we are endowed are unable to discover a future state, and if the most attentive consideration of their nature serves to show that they are adapted to this life and nothing more, it is surely inconsistent with any conception of justice that we should be dealt with, as if we had all along had a clear knowledge of the fact thus carefully concealed from us. What should we think of the justice of a father, who gave his son every reason to suppose that a trivial fault would only be visited by a box on the ear; and then, years afterwards, put him on the rack for a week for the same fault?
Again, the suggestion arises, if G.o.d is the cause of all things, he is responsible for evil as well as for good; and it appears utterly irreconcilable with our notions of justice that he should punish another for that which he has, in fact, done himself. Moreover, just punishment bears a proportion to the offence, while suffering which is infinite is _ipso facto_ disproportionate to any finite deed.
"Why then eternal punishment for the temporary offences of so frail a creature as man? Can any one approve of Alexander"s rage, who intended to exterminate a whole nation because they had seized his favourite horse Bucephalus?
"Heaven and h.e.l.l suppose two distinct species of men, the good and the bad; but the greatest part of mankind float betwixt vice and virtue. Were one to go round the world with the intention of giving a good supper to the righteous and a sound drubbing to the wicked, he would frequently be embarra.s.sed in his choice, and would find the merits and demerits of most men and women scarcely amount to the value of either."[43]
One can but admire the broad humanity and the insight into the springs of action manifest in this pa.s.sage. _Comprendre est a moitie pardonner_.
The more one knows of the real conditions which determine men"s acts the less one finds either to praise or blame. For kindly David Hume, "the d.a.m.nation of one man is an infinitely greater evil in the universe than the subversion of a thousand million of kingdoms." And he would have felt with his countryman Burns, that even "auld Nickie Ben" should "hae a chance."
As against those who reason for the necessity of a future state, in order that the justice of the Deity may be satisfied, Hume"s argumentation appears unanswerable. For if the justice of G.o.d resembles what we mean by justice, the bestowal of infinite happiness for finite well-doing and infinite misery for finite ill-doing, it is in no sense just. And, if the justice of G.o.d does not resemble what we mean by justice, it is an abuse of language to employ the name of justice for the attribute described by it. But, as against those who choose to argue that there is nothing in what is known to us of the attributes of the Deity inconsistent with a future state of rewards and punishments, Hume"s pleadings have no force. Bishop Butler"s argument that, inasmuch as the visitation of our acts by rewards and punishments takes place in this life, rewards and punishments must be consistent with the attributes of the Deity, and therefore may go on as long as the mind endures, is unanswerable. Whatever exists is, by the hypothesis, existent by the will of G.o.d; and, therefore, the pains and pleasures which exist now may go on existing for all eternity, either increasing, diminishing, or being endlessly varied in their intensity, as they are now.
It is remarkable that Hume does not refer to the sentimental arguments for the immortality of the soul which are so much in vogue at the present day; and which are based upon our desire for a longer conscious existence than that which nature appears to have allotted to us. Perhaps he did not think them worth notice. For indeed it is not a little strange, that our strong desire that a certain occurrence should happen should be put forward as evidence that it will happen. If my intense desire to see the friend, from whom I have parted, does not bring him from the other side of the world, or take me thither; if the mother"s agonised prayer that her child should live has not prevented him from dying; experience certainly affords no presumption that the strong desire to be alive after death, which we call the aspiration after immortality, is any more likely to be gratified. As Hume truly says, "All doctrines are to be suspected which are favoured by our pa.s.sions;"
and the doctrine, that we are immortal because we should extremely like to be so, contains the quintessence of suspiciousness.
In respect of the existence and attributes of the soul, as of those of the Deity, then, logic is powerless and reason silent. At the most we can get no further than the conclusion of Kant:--
"After we have satisfied ourselves of the vanity of all the ambitious attempts of reason to fly beyond the bounds of experience, enough remains of practical value to content us. It is true that no one may boast that he _knows_ that G.o.d and a future life exist; for, if he possesses such knowledge, he is just the man for whom I have long been seeking. All knowledge (touching an object of mere reason) can be communicated, and therefore I might hope to see my own knowledge increased to this prodigious extent, by his instruction. No; our conviction in these matters is not _logical_, but _moral_ certainty; and, inasmuch as it rests upon subjective grounds, (of moral disposition) I must not even say: _it is_ morally certain that there is a G.o.d, and so on; but, _I am_ morally certain, and so on. That is to say: the belief in a G.o.d and in another world is so interwoven with my moral nature, that the former can no more vanish, than the latter can ever be torn from me.
"The only point to be remarked here is that this act of faith of the intellect (_Vernunftglaube_) a.s.sumes the existence of moral dispositions. If we leave them aside, and suppose a mind quite indifferent to moral laws, the inquiry started by reason becomes merely a subject for speculation; and [the conclusion attained] may then indeed be supported by strong arguments from a.n.a.logy, but not by such as are competent to overcome persistent scepticism.
"There is no one, however, who can fail to be interested in these questions. For, although he may be excluded from moral influences by the want of a good disposition, yet, even in this case, enough remains to lead him to fear a divine existence and a future state.
To this end, no more is necessary than that he can at least have no certainty that there is no such being, and no future life; for, to make this conclusion demonstratively certain, he must be able to prove the impossibility of both; and this a.s.suredly no rational man can undertake to do. This negative belief, indeed, cannot produce either morality or good dispositions, but can operate in an a.n.a.logous fashion, by powerfully repressing the outbreak of evil tendencies.
"But it will be said, is this all that Pure Reason can do when it gazes out beyond the bounds of experience? Nothing more than two articles of faith? Common sense could achieve as much without calling the philosophers to its counsels!
"I will not here speak of the service which philosophy has rendered to human reason by the laborious efforts of its criticism, granting that the outcome proves to be merely negative: about that matter something is to be said in the following section. But do you then ask, that the knowledge which interests all men shall transcend the common understanding and be discovered for you only by philosophers? The very thing which you make a reproach, is the best confirmation of the justice of the previous conclusions, since it shows that which could not, at first, have been antic.i.p.ated: namely, that in those matters which concern all men alike, nature is not guilty of distributing her gifts with partiality; and that the highest philosophy, in dealing with the most important concerns of humanity, is able to take us no further than the guidance which she affords to the commonest understanding."[44]
In short, nothing can be proved or disproved, respecting either the distinct existence, the substance, or the durability of the soul. So far, Kant is at one with Hume. But Kant adds, as you cannot disprove the immortality of the soul, and as the belief therein is very useful for moral purposes, you may a.s.sume it. To which, had Hume lived half a century later, he would probably have replied, that, if morality has no better foundation than an a.s.sumption, it is not likely to bear much strain; and, if it has a better foundation, the a.s.sumption rather weakens than strengthens it.