Abacus, the logical, 199
Abscissio Infiniti (the cutting
off of the infinite or negative part),
the process by which we determine
the position of an object in a system
of classes, by successive comparison
and rejection of those classes to which
it does not belong.

Absolute terms, i.e. non-relative
terms, 25; sometimes used as name
of non-connotative terms, 41
Abstract terms, 20, 43
Abstraction, 285
Accent, fallacy of, 174
Accident, fallacy of, 176; the pre-
dicable, 103

Accidental definition is a defi-
nition which assigns the properties
of a species, or the accidents of an
individual; it is more commonly
called a Description.

Acquired perceptions, 236
Added determinants, inference
by, 86

Adequate knowledge, 56

A dicto secundum quid, &c.,
fallacy of, 176
Adjectives, 21
Adverbials, 93

Affirmative propositions, 63
Algebraic reasoning, 58, 219
Ambiguity of all, 20; of some, 79
of many old terms, 291; of terms in
Political Economy, 292
Ambiguous middle term, 130, 171
Amphibology, fallacy of, 172
Ampliative propositions, 69
Analogue, a thing analogous to
some other thing.
Analysis, method of, 205

Analogy, the cause of ambiguity,
35, 50; reasoning by, 226-8
Analytics, (тà AvaλUTɩka,) the title
given in the second century to por-
tions of the Organon, or Logical
Treatises of Aristotle; they were
distinguished as the Prior and Pos-
terior Analytics.

Analytic syllogism, a syllogism
in which the conclusion is placed
first, the premises following as the
reasons. See Synthetic Syllogism;
the distinction is unimportant.
Antecedent, of a hypothetical pro-
position, 160; of an event, 240
Anticipation of nature, 229
Antinomy (avri, against; vóμos,
law), the opposition of one law or rule
to another. Kant.

A posteriori knowledge, 208
A priori knowledge, 208

Arbor Porphyriana, see Tree of
Porphyry.

Argument, (Latin, argus, from

dpyòs, clear, manifest,) the process of
reasoning, the shewing or proving
that which is doubtful by that which
is known. See Inference. The mid-
dle term of a syllogism is sometimes
called specially the argument.
Argumentum a fortiori, an
argument in which we prove that
the case in question is more strong
or probable than one already con-
ceded to be sufficiently so.
Argumentum ad hominem,

Argumentum ad ignoranti-
am, an argument founded on the
ignorance of adversaries.
Argumentum ad populum,

179

Argumentum ad

verecun-

diam, an appeal to our respect for
some great authority.
Argumentum ex concesso,
a proof derived from a proposition
already conceded.

Aristotle's Dicta, 123
Art and Science, distinction of, 7
Artificial Classification, 284
Assertion, (ad, to; sero, to join,)
a statement or proposition, affirma-
tive or negative.

Association of ideas, (associo, to
accompany; socius, a companion,)
the natural connection existing in
the mind between impressions which
have previously coexisted, or which
are similar. Any idea tends to bring
into the mind its associated ideas, in
accordance with the two great laws
of association, the Law of Conti-
guity, and the Law of Similarity.
Assumption, (assumo, to take for
granted,) any proposition taken as
the basis of argument; in a special
sense, the minor premise of a cate-
gorical syllogism.

Attribute, (attribuo, to give or
ascribe to,) a quality or circumstance
which may be affirmed (or denied)
of a thing; opposed to Substance,
which see.

Attribute in grammar, 92
Attributive term, i. e. Connotative
term, 41

Axiom, defininition of, 125

Baconian method, 255; Philoso-
phy, 229

Barbara, Celarent, &c., 145
Begging the Question, 179
Belief, assent to a proposition, ad-
mitting of any degree of strength,
from the slightest probability to the
fullest certainty; see Probability.
Bentham, George, new system of
Logic, 187

Boole, George, his system of Logic,
191; his Laws of Thought, 197;
his logical works, 201

Canons of syllogism, 121-2; Hamil-
ton's supreme Canon, 189

Canons of Mill's Inductive Methods,
First, 240; Second, 242; Third, 245;
Fourth, 252; Fifth, 249
Categorematic words, 18
Categorical propositions, 63
Categories, the summa genera, or
most extensive classes into which
things can be distributed; they are
ten in number, as follows:

Ovoía, Substance; Пoσòv, Quan-
tity; Holov, Quality; IIpós T, Re-
lation; Ποιεῖν, Action; Πάσχειν,
Passion, or suffering; IIov, Place;
Πότε, Time; Κεῖσθαι, Position ;
"Exew, Habit or condition.

Everything which can be affirmed
must come under one or other of these
highest predicates, which were de-
scribed in the first treatise of Aris-
totle's Organon, called the Catego-
ries.

Cause, meaning of, 239

Aristotle distinguished four kinds
of causes for the existence of a thing
-1. The Material Cause, the sub-
stance or matter composing it; 2.
The Formal Cause, the pattern, type
or design, according to which it is
shaped; 3. The Efficient Cause, the
force employed in shaping it; 4.
The Final Cause, the end, motive
or purpose of the work.

Chance, ignorance of the causes
which are in action; see Probability.
Character, derivation of the word,
46

Characteristics, 285

Circulus in definiendo, 110, 114
Circulus in probando, 179
Clearness of knowledge, 54.
Cognition, (cognosco, to know,)
knowledge, or the action of mind in
acquiring knowledge.

Colligation of Facts, Dr Whewell's
expression for the mental union of
facts by some suitable conception,
see 286

Collective terms, 19

Combined or complete method of
investigation, 258

Comparison, (com, together; par,
equal or like,) the action of mind by
which we judge whether two objects

of thought are the same or different in certain points. See Judgment. Compatible terms are those which, though distinct, are not contradictory, and can therefore be affirmed of the same subject; as "large" and "heavy;" bright-coloured" and

66 nauseous." Complex conception, inference by, 87

Complex sentence, 91; syllogism, 158

Composition of Causes, the principle which is exemplified in all cases in which the joint effect of several causes is identical with the sum of their separate effects. J. S. Mill. See pp. 252, 265 Composition, fallacy of, 173 Compound sentence, 90 Comprehension of terms, see In

tension.

Computation, 127

Concept, that which is conceived, the result of the act of conception; nearly synonymous with general notion, idea, thought.

Conception (con, together; capio, to take). An ambiguous term, meaning properly the action of mind in which it takes several things together, so as to form a general notion; or again, in which it forms " a mental image of the several attributes given in any word or combination of words." Mansel. Conceptualists, 13 Conclusion of syllogism, 15, 127; weakened, 140 Concrete terms, 20

Conditional propositions, 62, 160 Confusion of words, ambiguity from, 31

Conjugate words, those which come from the same root or stock, as known, knowing, knowingly, knowledge.

Connotation of terms, 39, 41; ought to be exactly fixed, 290 Consciousness, the immediate knowledge which the mind has of its sensations and thoughts, and, in general, of all its present operations. Reid.

Consectary = Corollary.

Consequence, the connection between antecedent and consequent; but often used ambiguously for the latter. Consequent of a hypothetical proposition, 161

Consequent or effect of a cause,

240

Consequent, fallacy of the, 181 Conservation of energy, 263, 269 Consilience of Inductions, the agreement of inductions derived from different and independent series of facts, as when we learn the motion of the earth by entirely different modes of observation and reasoning. Whewell.

Consistency of propositions, 78 Consistent terms, see compatible

terms.

Contingent, (contingo, to touch,) that which may or may not happen; opposed to the necessary and impossible.

Contingent matter, 80 Continuity, Law of, the principle that nothing can pass from one extreme to another without passing through all the intermediate degrees; motion, for instance, cannot be instantaneously produced or destroyed. Contradiction, Law of, 117, 193 Contradictory terms, 24, 119; propositions, 76

Contraposition, conversion by, 83, 186

Converse fallacy of accident, 176
Conversion of propositions, 82-85;
with quantified predicate, 184
Convertend, 82

Coordinate propositions, 90
Copula, 16

Corollary, a proposition which fol lows immediately from another which has been proved.

Correction of observations, 253
Correlative terms, 25

Criterion (κριτήριον, from κρίνω, το judge), any fact, rule, knowledge, or means requisite to the formation of a judgment which shall decide a doubtful question.

Cross division, 105

Data, (plural of datum, that which

is given,) the facts or assertions from
which an inference is to be drawn.
Deduction and Induction, 212
Deductive or combined method,
258, 272

De facto, what actually or really
happens: opposed to de jure, what
ought to happen by law or right.
Definition, the logical process, 109,
112; of logic, I

Degree, terms expressing, 24; ques-
tions of, 120

Demonstration, (demonstro, to
point out,) strictly the pointing out
the connection between premises and
conclusion. The term is more ge-
nerally used for any argument or
reasoning regarded as proving an
asserted conclusion. A demonstra-
tion is either Direct or Indirect. In
the latter case we prove the conclu-
sion by disproving its contradictory,
or shewing that the conclusion cannot
be supposed untrue.

Demonstrative Induction, 220
Do Morgan's logical discoveries
and writings, 190

Denotation of terms, 39
Depth of a notion, see Intension.
Derivatives from the root spec,
sight, 52

Descartes on Method, 116, 229
Description, see Accidental Defi-
nition.

Descriptive terminology, 292
Destructive dilemma, 168; hypo-
thetical syllogism, 162-4
Desynonymization of terms, 49
Determination, the distinguishing
of parts of a genus by reunion of the
genus and difference. See Division.
Development of a term, 193
Diagrams, of sentences, 93-7; of
syllogisms, 129-133, 142; of pro-
positions, 72-75

Dialectic (διαλεχτικὴ τέκνη, the art

of discourse, from διαλέγεσθαι, το
discourse). The original name of
Logic, perhaps invented by Plato;
also used to denote the Logic of
Probable Matter (Aristotle), the
right use of Reason and Language,
the Science of Being; it is thus a
highly ambiguous term.

Dichotomy, division by, 107, 193

Discourse, or reasoning, 15
Discovery, method of, 202
Disjunctive, propositions, 62, 160;
syllogism, 166, 194

Distinct knowledge, 55

Distribution of terms, 19, 74-5,
82, 129

Division, logical, 105; metaphysical,
108; fallacy of, 174

Doubt, (dubito, to go two ways,) the
state of mind in which we hesitate
between two or more inconsistent
opinions. See Disbelief.

Drift of a proposition, the varying
meaning which may be attributed to
the same sentence according to ac-
centuation. See Fallacy of accent,
174-5

Empiricism (éμreipía, experience),
the doctrine of those who consider
that all knowledge is derived merely
from experience.
Empirical Law, 256
Enthymeme, 153
Epicheirema, 155
Episyllogism, 155
Equivocal terms, 29
Equivocation, 30; causes of, 31;
fallacy of, 171

Essence, (essentia, from esse, to be,)
"the very being of anything, where-
by it is what it is." Locke. It is an
ancient scholastic word, which can-
not be really defined, and should be
banished from use.
Essential propositions, 68
Euler's diagrams, 72-5, 129-133,

142

Evidence, (e, and videre, to see,)
literally the seeing of anything.
The word now means any facts ap-
prehended by the mind and made
the grounds of knowledge and belief.

119, 192
Exclusive propositions, 68
Exhaustive division, 107, 192
Experience, 228
Experimentum crucis, an ex-
periment which decides between two
rival theories, and shews which is to
be adopted, as a finger-post shews
which of two roads is to be taken.
Explanation, of facts, 264; of laws,
265

Explicative propositions, 68
Exposita, a proposition given to be
treated by some logical process.
Extensión and intension, 37, 208
Extensive Syllogism, 159
Extremes of a proposition, are its
ends or terms, the subject and predi-

Hamilton, Sir W., Method of No-
tation, 187

Herschel, Sir J., on active and
passive observation, 234

Heterogeneous, 101; intermix-
ture of effects, 252

Homogeneous, 101; intermixture
of effects, 252, 265
Homologue, whatever is homolo
gous.
Homology, a special term for the
analogy existing between parts of
different plants and animals, as be-
tween the wing of a bird and the
fore leg of a quadruped, or between
the scales of a fish and the feathers
.of a bird.

Homonymous terms, 30
Hypothesis, 269, 270
Hypothetical propositions, 62, 160;
syllogism, 161-2

Idea (idéa, eldos, image), a term used
ambiguously, but generally equiva-
lent to thought, notion, concept.
Defined by Locke as "Phantasm,
notion, species, or whatever it is
which the mind can be employed
about in thinking.". To have an idea
of a thing is to think of that thing.
Identity, law of, 117-8
Idol (eidwλov, eldos, image), Bacon's
figurative name for the sources of
error; he enumerated four kinds;
Idols of the Tribe, which affect all
people; Idols of the Cave, which are
peculiar to an individual; of the
Forum, which arise in the inter-
course of men; of the Theatre, which
proceed from the systems of philoso-
phers.

Ignoratio Elenchi, 178
Illation (illatum, past participle of

infero, to bring in). See Inference.
Illative, that which can be inferred.
Illicit process, of the minor term,
131; of the major term, 132, 139
Immediate inference, 85-7
Imperfect figures of the syllo-
gism, 145

Imperfect Induction, 213
Impossible matter, 80

Inconsistent terms imply qualities

which cannot coexist in the same
thing. See compatible terms,