, LOGIC. 



Salisbury. Ac., ft r., and a dictionary of scholastic philosophy and 

 Uwulory U is to be wished that the publiaher should circulate in 

 ITiMhin a distinct prospectus of the writers whose logical works have 

 been reprinted ; and it may be added, that a small addition to the 

 bulk of the whole work would make it* medieval logic nearly aa com- 

 plete at it* theology. The volume* are sold separately, and are very 



It U impossible to gire any account of the UUtory of the cubject 

 which WM first analysed by Aristotle, ao<l afterwmrds received from 

 Zeou the Stic, a* i* supposed, the name >!' /. " Tlut history is not 

 yet written in full. A history of one lugiosl idea, that of the CATK- 

 uoBira, was published by Trendeleiiberg a few yean since ; and re- 

 cently, a* we are told, the first volume of a professed history of the 

 whole subject has been published in Oennany by Prantl, which conies 

 down as far as Boethius inclusive. A sketch of leading point* and 

 MOM* is given by Mr. M"****!, in the introduction to hU edition of 

 Aldnch, dwelling briefly on the connection with logic of Zeno the 

 Eliajir. the sophirt* before Aristotle, Socrates, Plato, Aristotle, Theo- 

 phrastua, Kiulemus, Zeno and other Stoic*, the Epicurean*, Alexander 

 of AphrodisUs, Ammoniiu, Siuipliciu*, I'hiloponu-, 1'orphyry, Juhn of 

 Damascus, Photius, Psclliu, Blenimidas, Pachymeres, Leo Magcntinus, 

 George of Trebixond, Cicero, Apuleius, Augustine, Marcianus Capella, 

 Boethius, Oassiodorus, Avicenna, Averroes, Abelard, Qilbert Porreta- 

 mu, John of Salisbury, 1'eter Hispauus, Albettus Magnus, Tbomaa 

 Aquinas, Dun* Scotus, Occam, Kaymond Lully, Buridan, Hurley, 

 Laurentius Valla, Itodolphus Agricola, Ludovicus Vives, Peter Kamui, 

 Helancthon, Burgeradicius, Keckenuanu, Dowuame, Hilton, Bacon, 

 Descartes, Locke, Leibnitz, Hobbea, (iiwcndi, Clnuberg, Amauld and 

 Nicole, Burner, Le Clerc, Watts, Wolff, Baumgurten, Lambert, Plouc- 

 quet, Kant. So bare are the books of logic of all account of its 

 history, that a mere list of the name* which would be most prominent 

 in such a history, by which the student may resort to biographical 

 dictionaries or general historic* of philosophy, is a valuable addition to 

 t-.icli an article as the present. 



The great points of elementary logical investigation ore four in 

 number : 1. The name or Urn, the representative of one object of 

 thought, aa distinguished from others, including a mode of thinking. 

 3. The nlatiou, or mode of bringing two terms together, signified 

 by a C'pnta connecting two terms. 3. The pnpotitiun or judgment, a 

 relation between two terms affirmed or denied. 4. The igllogim, 

 deduction of a relation between two terms by means of the relations 

 of the two to a third term. These points must needs include the 

 consideration of all the laws of ratiocinative thought in action : surely, 

 What r What else '. What of them ! and What then ? are questions 

 which point to all that can take place in a mental process by which 

 thought leads to thought. Nevertheless, by certain restrictions which 

 we hold to be purely arbitrary, logicians have curtailed their science, 

 and made it appear to contain but u very small ]nrt of the processes 

 of actual thought. In placing before the student a mere sketch of 

 disputed point*, wo remind him tliat many things must be left 

 unsUted, many objection* mi;<i..\i,|,.l for. He must look for full 

 assurance, either for or against, in writings of more extended character, 

 and in discussion* which are fully guarded by the use of defined 



First, a* to the term or name, which may be in one word or in many. 

 The old logician* drew the distinction between a name used aa simply 

 denoting an external object, such as might It; thought of ascxi-un- 

 without any mind to think of it, and the name used as thinking of the 

 object in its mental relation to other objects. A max, thought of as 

 im individual pointed out, or a quality, as vhitt, the white of a par- 

 ticular white ball, were called names of Jinl intention, orjirtt notion*. 

 Hut HUM aa a claa*, or an individual thought of as a member of a class, 

 and whilr, as an attribute of classes, were names of tecond intention, or 

 ttttmd notion*.. The distinction is precisely that now known as 

 objective and subjective : and accordingly, we propose to consider 

 things not material thing* only and the qualities residing in them, 

 a* belonging to the objective use of names ; and classes, and the attri- 

 bute* by which we drtine classes, as belonging to the subjective use. 

 Now though the logician* have always professed to cultivate second 

 intention*, or subjective uses, the forms and the language of the 

 syllogism have been strictly fashioned on the objective use, ami :, 

 t remain so. 



i-lear that a name excludes as well as include* : every object 

 of thought U related to man, for instance, either a* in the name or ut. 

 The logician ba* alway* excluded the privative name, nut-man, for 

 instance, a* all but useless : a certain practice of hi* own really make* 

 it so. For he will have no tuurme or total sphere of thought except 

 the whole universe of possible existence; or, at narrowest, tin- wh..|i- 

 umv, r-.- uf objective reality. He forgets that, more often than not, 

 the universe of the existing topic of thought is limited. We are 

 talk ng of animals, for example, and nothing eUc : nol-man become* so 

 dcflniwly signibcativo that we have * separate name for it. lr<r. 

 Logic oujrfit to give us that command of thought which will pi event 

 our mental vision from being obstructed by the casual absence of a 

 name -lit to investigate the actual form uf thought u well 



a. possible scientific generalisation. 



Thirdly, two name* may be joined either u separate part* of a 

 common whole, or M jointly sopamUng the common part of two 



LOGIC. SM 



different wholes. Thus the class animal has the two separate sub-classes, 

 man and brute : but wan, under the name rational animal, U seen as 

 belonging to the common part of the two whole*, rational briny and 

 animal bring. We call the first procedure agyrtgation, the second 

 competition. The first process is mathematical : animal is made up of 

 MOM and l-nite after the same law of thought by which a square is made 

 up of two triangles. The second process is deep in the nature of 

 things, metaphysical : the combination of rational and animal into a 

 being such as man U not conceivable aa ay/reijation or addition, and no 

 more. Nevertheless the logician does not admit this : he announces 

 an object as the mm of all it* attribute*. The preceding distinction 

 divide* logic into two parts, which we call the mathematical and the 

 metaphysical ; not meaning that one part of logic is mathematics, and 

 another metaphysics, but that the distinctive features of the two sides 

 of logic are of prominent account, the one in mathematics, and the other 

 in metaphysics. 



'I'll'- distinction of composition and aggregation was conveyed and 

 implied in a few remarkable words of Aristotle, contained in his 

 Metaphysics : " The genus is said to be jiart of the species ; but in 

 point of view the species is part of the genus." Animal U 

 part of man : the whole notion (all the attributes) of animal forum part 

 (component) of the notion man. But man is part of animal : the whole 

 class (all the individuals) of man form part (aggregant) of the class 

 animal. This is the heading of a chapter in logic which only begins to 

 l>c written in full in our own day : the logicians always threw the idea 

 of attributes compounded of attributes into metaphysics, and retained 

 the mathematical notion of class aggregated of classes for logic. Tlio 

 attribute* which compound into an attribute were said to form ita 

 intention : the classes which aggregate into a class were said to form 

 union. This distinction of extension and intension or extent 

 and intent is now often styled that of cxtcn ion and otnnpnluaaioa ; 

 the Mills, father and son, call it that of denotation and connotation ; 

 Hamilton, that of breadth and depth. The revival of the distinction, 

 in logic, and as a separation of the two sides of logic, in mainly due to 

 Hamilton : but he and his followers have made a singular misconcep- 

 tion. In the above explanation it appears clearly that the logical 

 i/iianlities change terms ill the opposed modes of speaking. All aiiiiu.it 

 (nil the attributes) forms part of the notion man : all man (the whole 

 of the clans ^ i </ the class animal. According to Hamilton, 



the quantities do nut change places. He affirms that when we say 

 " All men are some animals," we speak * in depth ; and that when we 

 say " Some animals are all men " we speak in breadth. We shall not 

 enlarge upon this distinction : we do not think it necessary to impress 

 at length upon the reader that Hamilton's distinction is not the great 

 distinction of the laws of thought. And such discussion woidd be the 

 more inappropriate at this time, because Hamilton's logical lectures ore 

 on the eve of publication by Mr. Manscl, who may be expecti 

 his principal well, if defence be possible, and who must either d 

 or surrender. And we are glad of the opportunity of calling the 

 reader's anticipation to a work which will most surely contain a vast 

 breadth and depth of thought 



Lastly, every logical term is postulated as having existence in 

 thought, or existence in external reality, according to the in. 

 in question. It is only as representing existence that a term is used 

 in logic. Thus, When from every X is Y, ami every v is /. \ve infer 

 every x is z, our premises are supposed to imply the assertions that 

 x, Y, 7, exist. 



We now come to the copula or relation by wlu'ch terms an 

 nectcd, and the propotiliun or judijuuat, which assert* or denies the 

 connection. And here the logicians admit only one copula int > the 

 form of the proposition : that in, itti-Htirif<iti<ni, affirmed by if, dt nit d 

 by i* wot. If we say A goes before B, they call this proportion a 

 material connection l>etween A and B. They hold that the form of the 

 above which is essential to its consideration in pure logic is " A it a 

 thing which goes before B." And they further maintain that there are 

 three fundamental forms of thought, which they call the principles of 

 iilnilitil, ilijfcrrticc, and ,.iiil'lle. Of identity, A is A: of 



difference, A is not not- A (or B, other than A) ; of excluded middle (or 

 of nothing betvten), B is either A or not- A. That every thought of our 

 minds must be fashioned so as not to contradict either of these 

 principles is most evident ; as evident as the things themselves; as 

 sure as eggs are eggs. But the logician assumes a right to say that 

 only these propositions are of the pure form of thought, tin r l\v ill. 

 form : and that all others are true by the matter and not by the form. 

 Because all assertion identities something with something, ami all 

 denial separates something from something, he la;, i <i-,vn that 

 identity and difference constitute the only forms of c . mipan 

 ideas, or the whole form. Kor ourselves, we believe that th 



in the proposition " A is A," one specific relation, identity : we. 

 do not see why, except by arbitrary separation founded upon great 

 importance, the process of identification and the relation of identity 



Mr. Manuel (A'wtA Brit. Her., Mar, 1851), Invert* lUi mode uf reading. 

 lie will hove ' some A U all s' to mean that all the nttnlni'rt of the concept s arc 

 ome of the attributes of the concept A ; and ill u IB nonie A ' to mean that all the 

 iking* pomcMlng the mark (or name) B are a portion of thone posMtifnn the 

 mark A. \Vc mut leave the llamlltonian logician' to fettle among then 

 which i* which : that U, to array the to uropoMtioiu 'Some animal U all 

 man,' and ' all man ti tunic animal' under their proper banners. 



