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• Book III: Progress of Sciences
• Preface
• Sketch I: Principles and Progress of Reason
• Section I: Principles of Reason.
• Section II: Progress of Reason.
• Appendix: a Brief Account of Aristotle’s Logic. With Remarks.
• Chapter I.: Of the First Three Treatises.
• Chapter II.: Remarks.
• Chapter III.: Account of the First Analytics. 20
• Chapter IV.: Remarks.
• Chapter V.: Account of the Remaining Books of the Organon.
• Chapter VI.: Reflections On the Utility of Logic, and the Means of Its Improvement.
• Sketch II: Principles and Progress of Morality
• Part I: Principles of Morality
• Section I: Human Actions Analysed.
• Section II: Division of Human Actions Into Right, Wrong, and Indifferent.
• Section III: Laws of Nature Respecting Our Moral Conduct In Society.
• Section IV: Principles of Duty and of Benevolence.
• Section V: Laws Respecting Rewards and Punishments.
• Section VI: Laws Respecting Reparation.
• Section VII: Final Causes of the Foregoing Laws of Nature.
• Section VIII: Liberty and Necessity Considered With Respect to Morality.
• Appendix: Upon Chance and Contingency.
• Part II: Progress of Morality
• Sketch III: Principles and Progress of Theology
• Chapter I.: Existence of a Deity.
• Chapter II.: Progress of Opinions With Respect to Deity.
• Chapter III.: Religious Worship.
• Section I: Religious Worship Respecting the Deity Singly. 15
• Section II: Morality Considered As a Branch of Duty to Our Maker.
• Appendix: Sketches Concerning Scotland
• Sketch I: Scotch Entails Considered In Moral and Political Views 1
• Sketch II: Government of Royal Boroughs In Scotland
• Sketch III: Plan For Improving and Preserving In Order the Highways In Scotland
• Latin Tags and Phrases

CHAPTER II.

Remarks.

SECTION 1

On the Five Predicables.

The writers on logic have borrowed their materials almost entirely from Aristotle’s Organon, and Porphyry’s Introduction. The Organon however was not written by Aristotle as one work. It comprehends various tracts, written without the view of making them parts of one whole, and afterwards thrown together by his editors under one name on account of their affinity. Many of his books that are lost, would have made a part of the Organon if they had been saved.

The three treatises of which we have given a brief account, are unconnected with each other, and with those that follow. And although the first was undoubtedly compiled by Porphyry and the two last probably by Aristotle, yet I consider them as the venerable remains of a philosophy more ancient than Aristotle. Archytas of Tarentum, an eminent mathematician and philosopher of the Pythagorean school, is said to have wrote upon the ten categories; and the five predicables probably had their origin in the same school. Aristotle, though abundantly careful to do justice to himself, does not claim the invention of either. And Porphyry, without ascribing the latter to Aristotle, professes only to deliver the doctrine of the ancients and chiefly of the Peripatetics, concerning them.

The writers on logic have divided that science into three parts; the first treating of simple apprehension and of terms; the second, of judgement and of propositions; and the third, of reasoning and of syllogisms. The materials of the first part are taken from Porphyry’s Introduction and the Categories; and those of the second from the book of Interpretation.

A predicable, according to the grammatical form of the word, might seem to signify, whatever may be predicated, that is, affirmed or denied, of a subject: and in that sense every predicate would be a predicable. But logicians give a different meaning to the word. They divide propositions into certain classes, according to the relation which the predicate of the proposition bears to the subject. The first class is that wherein the predicate is the genus of the subject; as when we say, This is a triangle, Jupiter is a planet. In the second class, the predicate is a species of the subject; as when we say, This triangle is right-angled. A third class is when the predicate is the specific difference of the subject; as when we say, Every triangle has three sides and three angles. A fourth when the predicate is a property of the subject; as when we say, The angles of every triangle are equal to two right angles. And a fifth class is when the predicate is something accidental to the subject; as when we say, This triangle is neatly drawn.

Each of these classes comprehends a great variety of propositions, having different subjects, and different predicates; but in each class the relation between the predicate and the subject is the same. Now it is to this relation that logicians have given the name of a predicable. Hence it is, that although the number of predicates be infinite, yet the number of predicables can be no greater than that of the different relations which may be in propositions between the predicate and the subject. And if all propositions belong to one or other of the five classes above mentioned, there can be but five predicables, to wit, genus, species, differentia, proprium, and accidens. These might, with more propriety perhaps, have been called the five classes of predicates; but use has determined them to be called the five predicables.

It may also be observed, that as some objects of thought are individuals, such as, Julius Caesar, the city Rome; so others are common to many individuals, as good, great, virtuous, vicious. Of this last kind are all the things that are expressed by adjectives. Things common to many individuals, were by the ancients called universals. All predicates are universals, for they have the nature of adjectives; and, on the other hand, all universals may be predicates. On this account, universals may be divided into the same classes as predicates; and as the five classes of predicates above mentioned have been called the five predicables, so by the same kind of phraseology they have been called the five universals; altho’ they may more properly be called the five classes of universals.

The doctrine of the five universals or predicables makes an essential part of every system of logic, and has been handed down without any change to this day. The very name of predicables shews, that the author of this division, whoever he was, intended it as a complete enumeration of all the kinds of things that can be affirmed of any subject; and so it has always been understood. It is accordingly implied in this division, that all that can be affirmed of any thing whatever, is either the genus of the thing, or its species, or its specific difference, or some property or accident belonging to it.

Burgersdick, a very acute writer in logic, seems to have been aware, that strong objections might be made to the five predicables, considered as a complete enumeration: but, unwilling to allow any imperfection in this ancient division, he endeavours to restrain the meaning of the word predicable, so as to obviate objec-tions. Those things only, says he, are to be accounted predicables, which may be affirmed of many individuals, truly, properly, and immediately. The consequence of putting such limitations upon the word predicable is, that in many propositions, perhaps in most, the predicate is not a predicable. But admitting all his limitations, the enumeration will still be very incomplete: for of many things we may affirm truly, properly, and immediately, their existence, their end, their cause, their effect, and various relations which they bear to other things. These, and perhaps many more, are predicables in the strict sense of the word, no less than the five which have been so long famous.

Altho’ Porphyry and all subsequent writers, make the predicables to be, in number, five; yet Aristotle himself, in the beginning of the Topics, reduces them to four; and demonstrates, that there can be no more. We shall give his demonstration when we come to the Topics; and shall only here observe, that as Burgersdick justifies the fivefold division, by restraining the meaning of the word predicable; so Aristotle justifies the fourfold di-vision, by enlarging the meaning of the words property and accident.

After all, I apprehend, that this ancient division of predicables with all its imperfections, will bear a comparison with those which have been substituted in its stead by the most celebrated modern philosophers.

Locke, in his Essay on the Human Understanding, having laid it down as a principle, That all our knowledge consists in perceiving certain agreements and disagreements between our ideas, reduces these agreements and disagreements to four heads: to wit, 1. Identity and diversity; 2. Relation; 3. Coexistence; 4. Real Existence (a) . Here are four predicables given as a complete enumeration, and yet not one of the ancient predicables is included in the number.

The author of the Treatise of Human Nature,15 proceeding upon the same principle that all our knowledge is only a perception of the relations of our ideas, observes, “That it may perhaps be esteemed an endless task, to enumerate all those qualities which admit of comparison, and by which the ideas of philosophical relation are produced: but if we diligently consider them, we shall find, that without difficulty they may be comprised under seven general heads: 1. Resemblance; 2. Identity; 3. Relations of Space and Time; 4. Relations of Quantity and Number; 5. Degrees of Quality; 6. Contrariety; 7. Causation” (b) . Here again are seven predicables given as a complete enumeration, wherein all the predicables of the ancients, as well as two of Locke’s are left out.

The ancients in their division attended only to categorical propositions which have one subject and one predicate; and of these to such only as have a general term for their subject. The moderns, by their definition of knowledge, have been led to attend only to relative propositions, which express a relation between two subjects, and these subjects they suppose to be always ideas.

SECTION 2

On the Ten Categories, and on Divisions in general.

The intention of the categories or predicaments is, to muster every object of human apprehension under ten heads: for the categories are given as a complete enumeration of every thing which can be expressed without composition and structure; that is, of every thing that can be either the subject or the predicate of a proposition. So that as every soldier belongs to some company, and every company to some regiment; in like manner every thing that can be the object of human thought, has its place in one or other of the ten categories; and by dividing and subdividing properly the several categories, all the notions that enter into the human mind may be mustered in rank and file, like an army in the day of battle.

The perfection of the division of categories into ten heads, has been strenuously defended by the followers of Aristotle, as well as that of the five predicables. They are indeed of kin to each other: they breathe the same spirit, and probably had the same origin. By the one we are taught to marshal every term that can enter into a proposition, either as subject or predicate; and by the other, we are taught all the possible relations which the subject can have to the predicate. Thus, the whole furniture of the human mind is presented to us at one view, and contracted, as it were, into a nut-shell. To attempt, in so early a period, a methodical delineation of the vast region of human knowledge, actual and possible, and to point out the limits of every district, was indeed magnanimous in a high degree, and deserves our admiration, while we lament that the human powers are unequal to so bold a flight.

A regular distribution of things under proper classes or heads, is, without doubt, a great help both to memory and judgement. As the philosopher’s province includes all things human and divine that can be objects of enquiry, he is naturally led to attempt some general division, like that of the categories. And the invention of a division of this kind, which the speculative part of mankind acquiesced in for two thousand years, marks a superiority of genius in the inventer, whoever he was. Nor does it appear, that the general divisions which, since the decline of the Peripatetic philosophy, have been substituted in place of the ten categories, are more perfect.

Locke has reduced all things to three categories; to wit, substances, modes, and relations. In this division, time, space, and number, three great objects of human thought, are omitted.

The author of the Treatise of Human Nature has reduced all things to two categories; to wit, ideas, and impressions: a division which is very well adapted to his system; and which puts me in mind of another made by an excellent mathematician in a printed thesis I have seen.16 In it the author, after a severe censure of the ten categories of the Peripatetics, maintains, that there neither are nor can be more than two categories of things; to wit, data and quaesita.17

There are two ends that may be proposed by such divisions. The first is, to methodize or digest in order what a man actually knows. This is neither unim-portant nor impracticable; and in proportion to the solidity and accuracy of a man’s judgement, his divisions of the things he knows, will be elegant and useful. The same subject may admit, and even require, various divisions, according to the different points of view from which we contemplate it: nor does it follow, that because one division is good, therefore another is naught. To be acquainted with the divisions of the logicians and metaphysicians, without a superstitious attachment to them, may be of use in dividing the same subjects, or even those of a different nature. Thus, Quintilian borrows from the ten categories his division of the topics of rhetorical argumentation. Of all methods of arrangement, the most antiphilosophical seems to be the invention of this age; I mean, the arranging the arts and sciences by the letters of the alphabet, in dictionaries and encyclopedies. With these authors the categories are, A, B, C, &c.

Another end commonly proposed by such divisions, but very rarely attained, is to exhaust the subject divided; so that nothing that belongs to it shall be omit-ted. It is one of the general rules of division in all systems of logic, That the division should be adequate to the subject divided: a good rule, without doubt; but very often beyond the reach of human power. To make a perfect division, a man must have a perfect comprehension of the whole subject at one view. When our knowledge of the subject is imperfect, any division we can make, must be like the first sketch of a painter, to be extended, contracted, or mended, as the subject shall be found to require. Yet nothing is more common, not only among the ancient, but even among modern philosophers, than to draw, from their incomplete divisions, conclusions which suppose them to be perfect.

A division is a repository which the philosopher frames for holding his ware in convenient order. The philosopher maintains, that such or such a thing is not good ware, because there is no place in his ware-room that fits it. We are apt to yield to this argument in philosophy, but it would appear ridiculous in any other traffic.

Peter Ramus, who had the spirit of a re-former in philosophy, and who had force of genius sufficient to shake the Aristotelian fabric in many parts, but insufficient to erect any thing more solid in its place, tried to remedy the imperfection of philosophical divisions, by introducing a new manner of dividing. His divisions always consisted of two members, one of which was contradictory of the other; as if one should divide England into Middlesex and what is not Middlesex. It is evident that these two members comprehend all England: for the logicians observe, that a term along with its contradictory, comprehend all things. In the same manner, we may divide what is not Middlesex into Kent and what is not Kent. Thus one may go on by divisions and subdivisions that are absolutely complete. This example may serve to give an idea of the spirit of Ramean divisions, which were in no small reputation about two hundred years ago.

Aristotle was not ignorant of this kind of division. But he used it only as a touchstone to prove by induction the perfection of some other division, which indeed is the best use that can be made of it. When applied to the common purpose of division, it is both inelegant, and burdensome to the memory; and, after it has put one out of breath by endless subdivisions, there is still a negative term left behind, which shows that you are no nearer the end of your journey than when you began.

Until some more effectual remedy be found for the imperfection of divisions, I beg leave to propose one more simple than that of Ramus. It is this: When you meet with a division of any subject imperfectly comprehended, add to the last member an et caetera. That this et caetera makes the division complete, is undeniable; and therefore it ought to hold its place as a member, and to be always understood, whether expressed or not, until clear and positive proof be brought that the division is complete without it. And this same et caetera is to be the repository of all members that shall in any future time shew a good and valid right to a place in the subject.

SECTION 3

On Distinctions.

Having said so much of logical divi-sions, we shall next make some remarks upon distinctions.

Since the philosophy of Aristotle fell into disrepute, it has been a common topic of wit and raillery, to enveigh against metaphysical distinctions. Indeed the abuse of them in the scholastic ages, seems to justify a general prejudice against them: and shallow thinkers and writers have good reason to be jealous of distinctions, because they make sad work when applied to their flimsy compositions. But every man of true judgement, while he condemns distinctions that have no foundation in the nature of things, must perceive, that indiscriminately to decry distinctions, is to renounce all pretensions to just reasoning: for as false reasoning commonly proceeds from confounding things that are different; so without distinguishing such things, it is impossible to avoid error, or detect sophistry. The authority of Aquinas, or Suarez, or even of Aristotle, can neither stamp a real value upon distinctions of base metal, nor hinder the currency of those of true metal.

Some distinctions are verbal, others are real. The first kind distinguish the va-rious meanings of a word; whether proper, or metaphorical. Distinctions of this kind make a part of the grammar of a language, and are often absurd when translated into another language. Real distinctions are equally good in all languages, and suffer no hurt by translation. They distinguish the different species contained under some general notion, or the different parts contained in one whole.

Many of Aristotle’s distinctions are verbal merely; and therefore, more proper materials for a dictionary of the Greek language, than for a philosophical treatise. At least, they ought never to have been translated into other languages, when the idiom of the language will not justify them: for this is to adulterate the language, to introduce foreign idioms into it without necessity or use, and to make it ambiguous where it was not. The distinctions in the end of the Categories of the four words, prius, simul, motus, and habere, are all verbal.

The modes or species of prius, according to Aristotle, are five. One thing may be prior to another; first, in point of time; secondly, in point of dignity; thirdly, in point of order; and so forth. The modes of simul are only three. It seems this word was not used in the Greek with so great latitude as the other, although they are relative terms.

The modes or species of motion he makes to be six, to wit, generation, corruption, increase, decrease, alteration, and change of place.

The modes or species of having are eight. 1. Having a quality or habit, as having wisdom. 2. Having quantity or magnitude. 3. Having things adjacent, as having a sword. 4. Having things as parts, as having hands or feet. 5. Having in a part or on a part, as having a ring on one’s finger. 6. Containing, as a cask is said to have wine. 7. Possessing, as having lands or houses. 8. Having a wife.

Another distinction of this kind is Aristotle’s distinction of causes; of which he makes four kinds, efficient, material, formal, and final. These distinctions may deserve a place in a dictionary of the Greek language; but in English or Latin they adulterate the language. Yet so fond were the schoolmen of distinctions of this kind, that they added to Aristotle’s enumeration, an impulsive cause, an exemplary cause, and I don’t know how many more. We seem to have adopted into English a final cause; but it is merely a term of art, borrowed from the Peripatetic philosophy, without necessity or use: for the English word end is as good as final cause, though not so long nor so learned.

SECTION 4

On Definitions.

It remains that we make some remarks on Aristotle’s definitions, which have exposed him to much censure and ridicule. Yet I think it must be allowed, that in things which need definition and admit of it, his definitions are commonly judicious and accurate; and had he attempted to define such things only, his enemies had wanted great matter of triumph. I believe it may likewise be said in his favour, that until Locke’s essay was wrote, there was nothing of importance delivered by philosophers with regard to definition, beyond what Aristotle has said upon that subject.

He considers a definition as a speech declaring what a thing is. Every thing essential to the thing defined, and nothing more, must be contained in the definition. Now the essence of a thing consists of these two parts: First, What is common to it with other things of the same kind; and, secondly, What distinguishes it from other things of the same kind. The first is called the genus of the thing, the second its specific difference. The definition therefore consists of these two parts. And for finding them, we must have recourse to the ten categories; in one or other of which every thing in nature is to be found. Each category is a genus, and is divided into so many species, which are distinguished by their specific differences. Each of these species is again subdivided into so many species, with regard to which it is a genus. This division and subdivision continues until we come to the lowest species, which can only be divided into individuals, distinguished from one another, not by any specific difference, but by accidental differences of time, place, and other circumstances.

The category itself being the highest genus, is in no respect a species, and the lowest species is in no respect a genus; but every intermediate order is a genus compared with those that are below it, and a species compared with those above it. To find the definition of any thing, therefore, you must take the genus which is immediately above its place in the category, and the specific difference, by which it is distinguished from other species of the same genus. These two make a perfect definition. This I take to be the substance of Aristotle’s system; and probably the system of the Pythagorean school before Aristotle, concerning definition.

But notwithstanding the specious appearance of this system, it has its defects. Not to repeat what was before said of the imperfection of the division of things into ten categories, the subdivisions of each category are no less imperfect. Aristotle has given some subdivisions of a few of them; and as far as he goes, his followers pretty unanimously take the same road. But when they attempt to go farther, they take very different roads. It is evident, that if the series of each category could be completed, and the division of things into categories could be made perfect, still the highest genus in each category could not be defined, because it is not a species; nor could individuals be defined, because they have no specific difference. There are also many species of things, whose specific difference cannot be expressed in language, even when it is evident to sense, or to the understanding. Thus green, red, and blue, are very distinct species of colour; but who can express in words wherein green differs from red or blue?

Without borrowing light from the ancient system, we may perceive, that every definition must consist of words that need no definition; and that to define the common words of a language that have no ambiguity, is trifling, if it could be done; the only use of a definition being to give a clear and adequate conception of the meaning of a word.

The logicians indeed distinguish between the definition of a word, and the definition of a thing; considering the former as the mean office of a lexicographer, but the last as the grand work of a philosopher. But what they have said about the definition of a thing, if it have a meaning, is beyond my comprehension. All the rules of definition agree to the definition of a word: and if they mean by the definition of a thing, the giving an adequate conception of the nature and essence of any thing that exists; this is impossible, and is the vain boast of men unconscious of the weakness of human understanding.

The works of God are but imperfectly known by us. We see their outside; or perhaps we discover some of their qualities and relations, by observation and experiment assisted by reasoning: but even of the simplest of them we can give no definition that comprehends its real essence. It is justly observed by Locke, that nominal essences only, which are the creatures of our own minds, are perfectly comprehended by us, or can be properly defined; and even of these there are many too simple in their nature to admit of definition. When we cannot give precision to our notions by a definition, we must endeavour to do it by attentive reflection upon them, by observing minutely their agreements and differences, and especially by a right understanding of the powers of our own minds by which such notions are formed.

The principles laid down by Locke with regard to definition and with regard to the abuse of words, carry conviction along with them. I take them to be one of the most important improvements made in logic since the days of Aristotle: not so much because they enlarge our knowledge, as because they make us sensible of our ignorance; and shew that a great part of what speculative men have admired as profound philosophy, is only a darkening of knowledge by words without understanding.

If Aristotle had understood these principles, many of his definitions, which furnish matter of triumph to his enemies, had never seen the light: let us impute them to the times rather than to the man. The sublime Plato, it is said, thought it necessary to have the definition of a man, and could find none better than Animal implume bipes;18 upon which Diogenes sent to his school a cock with his feathers plucked off, desiring to know whether it was a man or not.

SECTION 5

On the Structure of Speech.

The few hints contained in the beginning of the book concerning Interpretation relating to the structure of speech, have been left out in treatises of logic, as belonging rather to grammar; yet I apprehend this is a rich field of philosophical speculation. Language being the express image of human thought, the analysis of the one must correspond to that of the other. Nouns adjective and substantive, verbs active and passive, with their various moods, tenses, and persons, must be expressive of a like variety in the modes of thought. Things that are distinguished in all languages, such as substance and quality, action and passion, cause and effect, must be distinguished by the natural powers of the human mind. The philosophy of grammar, and that of the human understanding, are more nearly allied than is commonly imagined.

The structure of language was pursued to a considerable extent, by the ancient commentators upon this book of Aristotle. Their speculations upon this subject, which are neither the least ingenious nor the least useful part of the Peripatetic philosophy, were neglected for many ages, and lay buried in ancient manuscripts, or in books little known, till they were lately brought to light by the learned Mr. Harris in his Hermes.

The definitions given by Aristotle, of a noun, of a verb, and of speech, will hardly bear examination. It is easy in practice to distinguish the various parts of speech; but very difficult, if at all possible, to give accurate definitions of them.

He observes justly, that besides that kind of speech called a proposition, which is always either true or false, there are other kinds which are neither true nor false; such as, a prayer, or wish; to which we may add, a question, a command, a promise, a contract, and many others. These Aristotle pronounces to have nothing to do with his subject, and remits them to oratory, or poetry; and so they have remained banished from the regions of philosophy to this day: yet I apprehend, that an analysis of such speeches, and of the operations of mind which they express, would be of real use, and perhaps would discover how imperfect an enumeration the logicians have given of the powers of human understanding, when they reduce them to simple apprehension, judgement, and reasoning.

SECTION 6

On Propositions.

Mathematicians use the word proposition in a larger sense than logicians. A problem is called a proposition in mathematics, but in logic it is not a proposition: it is one of those speeches which are not enunciative, and which Aristotle remits to oratory or poetry.

A proposition, according to Aristotle, is a speech wherein one thing is affirmed or denied of another. Hence it is easy to distinguish the thing affirmed or denied, which is called the predicate, from the thing of which it is affirmed or denied, which is called the subject; and these two are called the terms of the proposition. Hence likewise it appears, that propositions are either affirmative or negative; and this is called their quality. All affirmative propositions have the same quality, so likewise have all negative; but an affirmative and a negative are contrary in their quality.

When the subject of a proposition is a general term, the predicate is affirmed or denied, either of the whole, or of a part. Hence propositions are distinguished into universal and particular. All men are mortal, is an universal proposition; Some men are learned, is a particular; and this is called the quantity of the proposition. All universal propositions agree in quantity, as also all particular: but an universal and a particular are said to differ in quantity. A proposition is called indefinite, when there is no mark either of universality or particularity annexed to the subject: thus, Man is of few days, is an indefinite proposition; but it must be understood either as universal or as particular, and therefore is not a third species, but by interpretation is brought under one of the other two.

There are also singular propositions, which have not a general term but an individual for their subject; as, Alexander was a great conqueror. These are considered by logicians as universal, because, the subject being indivisible, the predicate is affirmed or denied of the whole, and not of a part only. Thus all propositions, with regard to quality, are either affirmative or negative; and with regard to quantity, are universal or particular; and taking in both quantity and quality, they are universal affirmatives, or universal negatives, or particular affirmatives, or particular negatives. These four kinds, after the days of Aristotle, came to be named by the names of the four first vowels, A, E, I, O, according to the following distich:

• Asserit A, negat E, sed universaliter ambae;
• Asserit I, negat O, sed particulariter ambo.19

When the young logician is thus far instructed in the nature of propositions, he is apt to think there is no difficulty in analysing any proposition, and shewing its subject and predicate, its quantity and quality; and indeed, unless he can do this, he will be unable to apply the rules of logic to use. Yet he will find, there are some difficulties in this analysis, which are overlooked by Aristotle altogether; and although they are sometimes touched, they are not removed by his followers. For, 1. There are propositions in which it is difficult to find a subject and a predicate; as in these, It rains, It snows. 2. In some propositions either term may be made the subject or the predicate as you like best; as in this, Virtue is the road to happiness. 3. The same example may serve to shew, that it is sometimes difficult to say, whether a proposition be universal or particular. 4. The quality of some propositions is so dubious, that logicians have never been able to agree whether they be affirmative or negative; as in this proposition, Whatever is insentient is not an animal. 5. As there is one class of propositions which have only two terms, to wit, one subject and one predicate, which are called categorical propositions; so there are many classes that have more than two terms. What Aristotle delivers in this book is applicable only to categorical propositions; and to them only the rules concerning the conversion of propositions, and concerning the figures and modes of syllogisms, are accommodated. The subsequent writers of logic have taken notice of some of the many classes of complex propositions, and have given rules adapted to them; but finding this work endless, they have left us to manage the rest by the rules of common sense.

[(a) ]Book 4. chap. 1.

[15. ]Hume.

[(b) ]Vol. 1. p. 33. and 125.

[16. ]Reid means James Gregory, professor of natural philosophy at St. Andrews in the late seventeenth century.

[17. ]“Things that are granted” and “things that are sought after.”

[18. ]“Two-footed animal without feathers.”

[19. ]“A asserts, E denies, but both do so universally; I asserts, O denies, but both do so particularly.”