Elements of logick

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ELEMENTS

OF

Preface

Of the few treatises of Logick which the author of the following compilation has perused, Duncan's has always appeared to him to be the best. But this treatise, however excellent, is for the most part too diffusive, and in some places, perhaps, even too scientifick, for the use of young beginners ; at the same time that it omits a number of particulars, of which (as they are generally taught in the schools, and occasionally alluded to in conversation as well as books) a teacher would not wish his pupils to be wholly ignorant. To obviate these objections, and yet retain as much as possible the features of Duncan, is the aim of the present compend; which was composed some years ago, and is now printed that the classes, for whose use it was intended, may no longer have the trouble of transcribing it.

ELEMENTS

OF

LOGICK.

Logigk is that science which explains the operations of the human understanding, in acquiring and communicating knowledge. And as these have been usually stated to be four,— apprehending, JUDGING, REASONING, and

arranging our thoughts in a suitable manner; so Logick, which treats of these operations, is usually divided into four parts.

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PART I. Of Simple Apprehension

Simple apprehension being that operation of the mind by which it is furnished with ideas, a treatise on it, is, in a great measure, a treatise on ideas, and on the procedure of the mind with respect to them: and it is also a treatise on words and definitions; because, without these, we should often be at a loss both in acquiring and communicating our ideas. The first part, therefore, of Logick, may be divided into two chapters: One treating of ideas; and the other, of terms and definitions,

CHAPTER I. Of Simple Apprehension^ and the faculties

by which it is exerted. Of ideas ^ or the

first principles of knowledge.... *.0f the sources from which they are derived; and of the different sorts of them.

Simple Apprehension is that operation of the understanding by which it attends to, and notices, the several objects that are presented to it. It is caLled simple apprehension, because it is employed in the mere apprehending or noticing of things : without comparing them with each other, or assigning to them any attributes; which is the province of judgment. And by this operation it is, that the mind, as we have already observed, is furnished with ideas : for without previously attending to, and noticing, the objects that are presented to it, it is impossible that the mind should ever have any ideas of them ; or, in other words, be able to represent to itself the appearances which they exhibit.

In performing this operation, two faculties are made use of, which are quite distinct from each other; sensation, and consciousness. If the object occurring be an external thing, the mind perceives it, and its qualities, by means of the senses ; and the power of doing this is called the faculty of sensation: if it be an internal thing, that is, if it be any operation or emotion of the mind, the mind attends to and notices it,

9 without making use, so far as we know, of any bodily organ ; and it is this power, which we call the faculty .of consciousness.

The term idea is derived from the Greek word eJJW, I see ; and by ideas are meant, the views which the mind takes of things, when they are no longer present. In the language of the schools, ideas are the types or resemblances of things; and things themselves are the archetypes, or originals of which the resemblances are made. When an external object is present, and attended to by my mind, I am said to perceive it; and when my mind is engaged in any operation, or agitated by any passion or emotion, I am said to be conscious of that operation, or of that passion or emotion : but when the external object is no longer present, so as to affect the organs of sense, or when the operation which had engaged my mind has ceased to engage it, or the passion or emotion, by which I was agitated, now agitates me no more, I am capable of thinking of the object which I before perceived, or of the operation or emotion of which I was conscious, and of representing to myself the appearances which they respectively exhibited ; and when I do so, I am said to have ideas of them.

It has been stated, that all external things and their qualities are noticed by means of the senses; and internal things, that is, the operations and emotions of the mind, by consciousness : now all the objects of which we have any know-

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ledge, are either external things and their qualities, or the operations and emotions of the mind: and, consequently, all our ideas, how numerous soever they may be, are derived from these two sources.

As ideas are the first elements of all our knowledge; so sensation and consciousness are the first of our intellectual faculties which are exerted by us. And as we can have no ideas of the operations of our own minds until these operations are exerted; and as they cannot be exerted, before the mind is furnished with ideas of external things about which to employ them ; the ideas which give the first employment to our faculties, are evidently the ideas of external things, communicated by the senses : whence it

12 is plain, that all our knowledge must begin in sensation ; and that the operation of this faculty is prior even to that of consciousness.

Ideas are either simple or complex. A simple idea is an idea of a simple object ; that is, of an object without parts : or it may be defined, an idea which cannot be resolved into two or more ideas. A complex idea is an idea of a complex object ; that is, of an object that consists of parts: or, it is an idea, that may be resolved into two or more ideas.

To the former of these classes belong all our ideas of qualities, and of the operations and emotions of our own minds. The qualities of external things are called sensible qualities; and may be reduced to five general heads.

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according to the several senses which are affected by them. Light and colours are perceived by the eye ; sounds, by the ear ; tastes, by the tongue ; smells, by the nose ; and heat and cold, roughness and smoothness, hardness and softness, &c., by the touch. Extension, figure, rest, and motion, we perceive by two senses ; seeing, and feeling. To which may be added, that our ideas of pleasure and pain, of power, existence, unity, and succession, are conveyed into our understandings both by sensation and consciousness ; that is, both by the action of objects around us, and the consciousness of what we feel within. Other qualities are intellectual,

MORAL, &C.

To this general view of our simple B ideas may be subjoined the two following observations. Thtjirst is, that simple ideas can only be conveyed into the mind by the proper channels and avenues provided by nature ; insomuch that if we are destitute of any of those inlets, all the ideas, thence arising, are absolutely lost to us ; nor can we, by any quickness of understanding, find a remedy for this want. A man born blind is incapable of ideas of light and colours; as one, who is born deaf, can form no conception of sounds. And hence it appears, that these our simple ideas are just such as nature furnishes them* and have no dependence on our will: we can neither destroy them when in the understanding; nor fashion or invent any new one, not taken in by

15 the ordinary means of apprehension. So that the utmost bounds of human knowledge cannot exceed the limits of our simple ideas and their various combinations- The second is, that though the mind, in multiplying its conceptions, can avail itself of no other materials than those which are furnished by sensation and consciousness; yet, as it has a power of combining these materials in a great variety of ways, it finds itself in possession of an inexhaustible treasure of ideas, sufficient to employ it to the full extent of its powers.

Complex ideas are of two sorts: those

WHICH ARE CONVEYED INTO THE MIND BY THINGS REALLY EXISTING IN NA- TURE; and those which are the

WORKMANSHIP OF THE MIND ITSELF*

Things really existing in nature are all comprised under the general name of substances; which are either material or immaterial. And the usual definition of a substance is, that it is a thing which subsists of itself, without dependence upon any created being, and is the subject of modes/* The idea, for example, of a material substance includes in it the idea of a thing subsisting of itself; and the ideas of its qualities, by which only, as we find by experience, it is made known to us : the idea of an immaterial substance, in like manner, includes the idea of a thing subsisting of itself; and the ideas of its operations, by which only, as we also find by experience, it is made known to us. And hence it appears that it is not without reason, that

• That is, of qualities or attributes

17 all our ideas of substances are considered as complex ideas.

Modes are divided into essential and accidental. An essential mode is that which cannot be separated from its subject, without destroying the nature of the subject: an accidental mode is that which may be separated from its svibject, and the nature of its subject remain the same as it was before. Roundness, for example, is an essential mode of a ball; because a thing cannot be a ball without being round: but any particular colour is an accidental mode of a ball; because if a ball, which is now blue, were to be painted white, it would still be a ball as much as ever.

Essential modes are divided into primary and secondary. A primary es-

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18 sential mode is that which is derived from no other mode, and constitutes a thing what it is. A secondary essential mode is that, which, although inseparable from its subject, is derived from some other mode. Thus roundness is a primary essential mode of a ball ; because we do not conceive of it as derived from any ether quality of a ball: but volubility, or aptness to roll, is a secondary essential mode of a ball; because it arises from another quality of it, that is, its roundness. The primary essential mode has been called differentia, or the difference; the secondary essential mode, proprium, or a property; and the accidental mode, accidens.

Complex ideas, which are the workmanship of the mind, are divided into

COMPOUND, UNIVERSAL, GENERAL, OY

ABSTRACT, and RELATIVE.

Compound ideas are those, which the mind forms by putting two or more ideas together. These combinations are sometimes made by adding the same* idea to itself; thus, by adding the idea of unity to itself repeatedly, and retaining the several amounts in our minds, we come by all the different combinations of numbers: in the same way are formed the different ideas of yards, perches, furlongs, miles, leagues, &c. ; also those of weeks, months, years, he. But, more frequently, our compound ideas are formed by combining ideas of a different kind together. The composer of musick, for example, forms the idea of a tune which he is composing, and the

20 mechanick> the idea of a machine which he is projecting, — by bringing together, in the former case, a number of notes — and, in the latter, of parts, — that are different from each other.

An abstract, universal, or, as it is more commonly called, a general idea, is an idea that will apply to several individuals, or to several classes of individuals. If it apply to individuals only, the class, which corresponds to it, and comprehends individuals, is termed a species; if to several classes of individuals, the class which corresponds to it, and comprehends these several classes of individuals, is termed a genus. The formation of these ideas depends on a power which the mind possesses of removing, from its idea of any object, what is peculiar to that object; from its idea of an individual, whatever is peculiar to that individual ; and from its idea of a "species, whatever is peculiar to that species: a power, which, by the writers on the human mind, is called the faculty of abstraction. And hence it appears, that it is not without reason, that our general ideas are ranked among those which are the workmanship of the mind, and have nothing in nature to which they correspond.

But that this may be better understood, it will be worth while to take a more distinct view of the process of the understanding in the formation of these ideas. All the things in nature are individual things: that is, every thing is itself, and one; and not another, and more than one. But when we come to take a view of the several individuals, and observe that a number of them resemble each other in one or more particulars of importance, selecting the particulars in which they agree, and removing all those in which they disagree, we frame to ourselves a general idea applicable to several individuals ; that is, to a particular species. Thus certain animals being found to resemble each other in having an erect form, and in being endowed with the faculties of reason and speech, we take these important particulars which are common to them all, and excluding what is peculiar to each, we form a general idea, to which we give the name of man; and this name belongs equally to every indivi-

23 dual who is possessed of the form and faculties above mentioned. This is the first step or gradation in the forming of abstract ideas, when the mind confines

itself to the consideration of individuals, and frames an idea that comprehends such only under it.

Again: having ranged things into species, according to the resemblance found among them, we begin to compare the several species with each other ; and often observe, in these also, a resemblance, in one or more particulars of importance. Upon this, throwing out all the particulars in which they disagree, and retaining those only, in which there is a resemblance, we frame a still more general idea, comprehending under it several species. Thus, a sparrow, a hawk, an eagle, &x. are distinct species of birds : they nevertheless resemble each other in being covered with feathers, and provided with wings which bear them through the air : out of these particulars we form a new idea, and appropriating to it the name bird, mark by that word a higher class, which comprehends in it all the former. This higher class, which extends to several species of things, is called a genus ; and is the second step which the mind takes in the formation of its general ideas.

But, in rising from particulars to generals, the mind does not confine itself to one or two gradations. For when we have reduced things into species, and these again into genera, these genera are often found to resemble each other

25 in some particulars, which being combined together into one idea includes a new and more comprehensive class of things. Thus bird is a genus, comprehending the several species of sparrow, hawk, eagle, he. : fish is a genus, including the several species of living creatures which inhabit the waters, as dolphins, sturgeons, &c. : beast or quadruped, and insect, are also genera, which extend to many species : yet all these different genera have this in common, that they are provided with organical bodies fitted for the purposes of life and spontaneous motion. An idea, therefore, made up of these particulars only, will comprehend all the genera above mentioned ; and the word, animal, by which it is expressed, denotes a

26 higher genus, including the several creatures endued with life, sense, and spontaneous motion.

Further : all things, animate and inanimate, resemble each other in this respect, that they are created; whence we refer them to a genus still higher, which may be called creature : a name, which belongs equally to every genus and species of created things, and to each individual thing that is created.

And further still: all things, whatever, exist, or are ; and in this respect are said to resemble each other; in which view we refer them to a genus still higher, called Being, which is the highest possible genus.

In a series of genera, rising in this manner one above another, each successive genus is called, in the schools, a

GENUS GENERALIUS, Or HIGHER GENUS;

and the genus by which each series is terminated, they distinguish by the name of genus generalissimum. In like manner, the several genera, comprehended under a higher genus, are, in respect to it, considered as species; and as these have also species under them, the inferior divisions are, for the sake of distinction, termed species specialiores, or lower species. And the lowest subdivisions of all, comprehending only individuals, (which, as has been already mentioned, constitute the proper species) are, in respect to the series, denominated the species specialissimje. All that lie between these and the highest distribution of things, or genus

28 generalissimum, are the intermediate genera and species ; which are termed successively genus generalius, or species specialior, according as we consider them in the ascending, or descending, scries of our ideas ; or, to speak in the language of logicians, according to their ascent, or descent, in the linea predicament all.

And here we may take occasion to mention merely, that, by the ancient writers of logick, a genus generalissimum, with all its divisions and subdivisions, was termed a category, or predicament. And as Aristotle fancied, that all things in nature might be reduced to ten general heads, or classes, namely, substance, quantity, quality, relation, action, passion, place, time, situation,

29 and doathing; these have been called

THE TEN CATEGORIES.

It is of more importance to remark, that, though many of our general ideas are evidently combinations of different simple ideas, and in that view of them are included in the class of compound ideas, we are carefully to distinguish between an idea as it is compound, and as it is general or universal.

An idea is termed compound, with respect to the several ideas which are combined in it; general or universal, with respect to the individuals, species, or genera, to which it extends. Thus the idea of a bird, considered as a compound idea, includes life, sense, spontaneous motion, a covering of wings, feathers, he. : but, as a general idea, it de-

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30 notes the several species of the feathered creation, the hawk, the eagle, the lark, &c. ; to all which it extends with equal propriety. In the former case, the several parts of the compound idea are called its comprehension; in the latter, the genera, the species, and the individuals, to which the universal idea may be applied, are called its extension.

The third and last division, of those complex ideas which are the workmanship of the mind, consists of our relative ideas. A relative idea, is an idea which arises from the comparing of things, one with another, and observing their correspondencies. For the mind is not limited to the consideration of objects, as they are in themselves merely; but can examine them as connected with other

31 things brought into view at the same time. And when it does so, and thence acquires new ideas, the ideas thus acquired are called relative ideas; and make, as is supposed, the largest class of our ideas. For every single object will admit of almost innumerable comparisons with others, and, in this way, may become a very plentiful source of ideas to the understanding. Thus, if we compare one thing with another in respect to bulk, we get the idea of greater and less, or of equality: if, in respect of time, of older and younger: and so of other relations, which we can pursue at pleasure, and almost without end.

So much, with respect to ideas ; which are the subject of the first chapter. We have stated, that all our simple ideas are conveyed into the understanding either by sensation or consciousness ; and are the materials out of which all others are formed: that the mind, though it has no power over these, either to fashion or to destroy them, can yet combine them in an infinite number of ways ; and that from their various combinations result all our complex ideas : that these complex ideas are of two principal kinds ; first, such as are derived from without, and represent those combinations of simple ideas that have a real existence in nature, — of which sort are all our ideas of substances ; secondly, such as are formed by the mind itself, arbitrarily uniting and putting together its ideas: and that, as these last make by far the largest class, and comprehend all those ideas which may be properly termed our own, as being the workmanship of the understanding ; so they fall very naturally under three distinct heads. For either the mind combines several simple ideas together in order to form them into one complex idea, in which the number and quality of the ideas united are principally considered; in which way we become possessed of all our compound ideas: or it fixes upon any one of its ideas, whether it be a simple or compound idea, or an idea of a substance, and leaving out the circumstances of time, place, real existence, and whatever renders it particular, considers what it has in common with others, and of that makes an idea which will apply to all of a kind ; whence our ab-

34 stract or universal ideas are derived: or, lastly, it compares things one with another, examines their mutual connections, and thereby furnishes itself with a new set of ideas, known by the name of relative ideas ; which, as has been already remarked, make by no means the the least important class of our ideas.

CHAPTER II. Of Terms and Definitions

Having seen, in the preceding chapter, how our ideas are acquired; let us now proceed to examine how they are communicated. Ideas themselves are not visible, nor can they be perceived by any outward sense. But God, designing us for society, and to have fellowship with those of our kind, has provided us with organs fitted to frame articulate sounds, and given us also a capacity of using those sounds, or terms, as signs of ideas. Hence our ideas, which otherwise must have been locked up, as it were, in our own breasts, are brought •forth and made to appear. For, any number of men having agreed to make use of the same sounds as signs of the same ideas, it is evident, that the repetition of these sounds must excite the same ideas in them all. When, for instance, any train of ideas takes possession of my mind, if the terms, or sounds, by which I am wont to express them, have been annexed, by those with whom I converse, to the very same set of ideas, nothing is more evident, than that by repeating those terms, according to the tenour of my ideas, I shall raise in their minds the same train that has taken possession of my own. Hence, by barely attending to what passes within themselves, they will also become acquainted with the ideas in my understanding, and have them in a manner exposed to their view.

So that we here clearly perceive how a man may communicate his sentiments to another; provided the language, in which he converses, be copious enough to contain words appropriated to all his ideas; and provided the person, to whom he speaks, is possessed of the same ideas which he expresses, and has been accustomed to connect them with the same terms.

But as this is not always the case, and as we may often have occasion to communicate to others a new idea, that is, an idea that has never yet entered their minds, and which consequently

D they cannot as yet have connected with any term; it may be asked, by what means it is possible that the communication of such an idea should be effected.

This appears to be a difficulty; and, to solve it, it will be necessary to observe, first, that no word can be to any man the sign of an idea, till that idea comes to have a real existence in his mind. For words being only so far intelligible, as they denote known ideas; where they have none such to answer to them, there they are plainly sounds without signification, and of course convey no information. But no sooner are the ideas, to which they belong, produced in the understanding, than, finding it easy to connect them with the

39 established words, we can join in any agreement of this kind made by others, and enjoy the benefit of their discoveries. The first thing, therefore, to be considered, is, how these ideas may be conveyed into the mind, that, they being there, we may learn to connect them with the appropriated sounds, and so become capable of understanding others when they make use of these sounds in laying open and communicating their thoughts. Now to comprehend distinctly how this may be done, it will be necessary to call to mind the before mentioned divisions of our ideas into simple and complex. And first, as to our simple ideas, it has been already observed, that they can find no admission into the mind, but by the original

40 fountains of knowledge ; sensation, and consciousness. If therefore any of these have as yet no being in the understanding, it will be impossible by words to excite them there. A man, who had never felt the impression of heat, could not be brought to comprehend that sensation, by any thing which we could say to explain it. If we would produce the idea in him, it must be by applying the proper object to his senses, and bringing him within the influence of a hot body. When this is done, and experience has taught him the sensation, to which men have annexed the name, hecit^ this term may then become to him the sign of that idea; and he is thenceforth capable of understanding the meaning of the term; which, before, all

41 the words in the world would not have been sufficient to convey into his mind. The case is the same with respect to light and colours : a man born blind, and by this misfortune destitute of the only conveyance for the ideas of these objects, can never be brought to understand the terms by which they are expressed. The reason is plain: they stand for ideas which have no existence in his mind ; and as the organ, appropriated to their reception, is wanting, all other contrivances are vain, nor can these ideas, by any force of description, be excited in him. But, with our complex ideas, it is quite otherwise. For these being no other than certain combinations of simple ideas put together in various forms ; if the simple ideas,

D2 out of which the complex ideas are made, have already got admission into the understanding, and the terms serving to express them be known, it will be easy, by enumerating the several ideas included in the combination, and marking the order and manner in which they are united, to raise any complex idea in the mind. Thus the idea answering to the term, rainbow, may be readily excited in the imagination of another, who has never seen the appearance itself, by describing the figure, size, position, and order of colours; if we suppose these several simple ideas, with their names, sufficiently known to him.

The answer, then, to the question proposed above, is now sufficiently ob-

43 vious. If the new idea, which we wish to communicate to others, be a simple idea, there is no other w r ay than to refer them to those objects in nature whence the idea is to be obtained: but, if it be a complex idea, its meaning may be explained by enumerating the ideas included in it ; that is, by defining it.

And here we see the nature and use of definitions. They are used to unfold a complex idea ; and two things are required in them: first, that all the simple ideas, out of which the complex one is formed, be distinctly enumerated; and, secondly, that the order and manner of combining them be clearly explained. Where a definition has these requisites, nothing is wanting to its perfection; because every one, who reads it, and un-

44 derstands the terms, seeing at once what ideas he is to join together, and also in what manner, can, at pleasure, form, in his own mind, the complex idea answering to the term defined.

But this rule, though it extends to all possible cases, and is indeed that alone to which we can have recourse where any doubt or difficulty arises, it is not, however, necessary, or even expedient, to practise in every particular instance. Many of our ideas are extremely complex ; and, of course, to enumerate all the simple ideas, out of which they are formed, would be a very troublesome and tedious work. For which reason, logicians have established a certain compendious mode of defining; of which, it may not be amiss to give here a short account. If the thing to be defined be a species, they give the nearest genus and the specifick difference; or, in other words, they refer it to its nearest genus, and then add those circumstances that make the species, which they are defining, to differ from every other species belonging to that genus. For, as the idea of a genus is formed by dropping what is peculiar to each of the several species referred to it, and retaining those particulars which they all possess in common; so, on the other hand, by adding to the genus what is peculiar to any one of the species included in it, we form an adequate idea, and give a complete definition, of that species. In like manner, if the thing to be defined be an individual, the logical definition will consist of the species and the numerical difference; or, in other words, of the species, and those particulars that distinguish the individual which we are defining, from every other individual belonging to that species. For, as the idea of a species is formed by dropping what is peculiar to the several individuals referred to it, and retaining those particulars only which they possess in common ; so, by adding to the species what is peculiar to any one of the individuals included in it, we form an adequate idea, and give a complete definition, of that individual.