6. The _Sophistical Elenchi_, on sophistical or contentious syllogism,
or sophistical fallacies.
So far as we know, Aristotle had no one name for all these
investigations. "Analytics" is only applied to the _Prior_ and
_Posterior Analytics_, and "logical," which he opposed to
"analytical," only suits the _Topics_ and at most the _Sophistical
Elenchi_; secondly, while he analyzed syllogism into premises, major
and minor, and premises into terms, subject and predicate, he
attempted no division of the whole science; thirdly, he attempted no
order and arrangement of the treatises into a system of logic, but
only of the _Analytics_, _Topics_ and _Sophistical Elenchi_ into a
system of syllogisms. Nevertheless, when his followers had arranged
the treatises into the _Organon_, as they called it to express that it
is an instrument of science, then there gradually emerged a system of
syllogistic logic, arranged in the triple division--terms,
propositions and syllogisms--which has survived to this day as
technical logic, and has been the foundation of all other logics, even
of those which aim at its destruction.
The main problem which Aristotle set before him was the analysis of
syllogism, which he defined as "reasoning in which certain things having
been posited something different from them of necessity follows by their
being those things" (_Prior Analytics_, i. 1). What then did he mean by
reasoning, or rather by the Greek word [Greek: logos] of which
"reasoning" is an approximate rendering? It was meant (cf. _Post. An._
i. 10) to be both internal, in the soul ([Greek: ho esô logos, en tê
psychê]), and external, in language ([Greek: ho exo logos]): hence after
Aristotle the Stoics distinguished [Greek: logos endiathetos] and
[Greek: prophorikos]. It meant, then, both reason and discourse of
reason (cf. Shakespeare, _Hamlet_, i. 2). On its mental side, as reason
it meant combination of thoughts. On its linguistic side, as discourse
it was used for any combination of names to form a phrase, such as the
definition "rational animal," or a book, such as the _Iliad_. It had
also the mathematical meaning of _ratio_; and in its use for definition
it is sometimes transferred to essence as the object of definition, and
has a mixed meaning, which may be expressed by "account." In all its
uses, however, the common meaning is combination. When Aristotle called
syllogism [Greek: logos], he meant that it is a combination of premises
involving a conclusion of necessity. Moreover, he tended to confine the
term [Greek: logos] to syllogistic inference. Not that he omitted other
inferences ([Greek: pisteis]). On the contrary, to him (cf. _Prior
Analytics_, ii. 24) we owe the triple distinction into inference from
particular to particular ([Greek: paradeigma], example, or what we call
"analogy"), inference from particular to universal ([Greek: epagôgê],
induction), and inference from universal to particular ([Greek:
syllogismos], syllogism, or deduction). But he thought that inferences
other than syllogism are imperfect; that analogical inference is
rhetorical induction; and that induction, through the necessary
preliminary of syllogism and the sole process of ascent from sense,
memory and experience to the principles of science, is itself neither
reasoning nor science. To be perfect he thought that all inference must
be reduced to syllogism of the first figure, which he regarded as the
specially scientific inference. Accordingly, the syllogism appeared to
him to be the rational process ([Greek: meta logou]), and the
demonstrative syllogism from inductively discovered principles to be
science ([Greek: epistêmê]). Hence, without his saying it in so many
words, Aristotle's logic perforce became a logic of deductive reasoning,
or syllogism. As it happened this deductive tendency helped the
development of logic. The obscurer premises of analogy and induction,
together with the paucity of experience and the backward state of
physical science in Aristotle's time would have baffled even his
analytical genius. On the other hand, the demonstrations of mathematical
sciences of his time, and the logical forms of deduction evinced in
Plato's dialogues, provided him with admirable examples of deduction,
which is also the inference most capable of analysis. Aristotle's
analysis of the syllogism showed man how to advance by combining his
thoughts in trains of deductive reasoning. Nevertheless, the wider
question remained for logic: what is the nature of all inference, and
the special form of each of its three main processes?
As then the reasoning of the syllogism was the main problem of
Aristotle's logic, what was his analysis of it? In distinguishing
inner and outer reason, or reasoning and discourse, he added that it
is not to outer reason but to inner reason in the soul that
demonstration and syllogism are directed (_Post. An._ i. 10). One
would expect, then, an analysis of mental reasoning into mental
judgments ([Greek: kriseis]) as premises and conclusion. In point of
fact, he analysed it into premises, but then analysed a premise into
terms, which he divided into subject and predicate, with the addition
of the copula "is" or "is not." This analysis, regarded as a whole and
as it is applied in the _Analytics_ and in the other logical
treatises, was evidently intended as a linguistic analysis. So in the
_Categories_, he first divided things said ([Greek: ta legomena]) into
uncombined and combined, or names and propositions, and then divided
the former into categories; and in the _De interpretatione_ he
expressly excluded mental conceptions and their combinations, and
confined himself to nouns and verbs and enunciations, or, as we should
say, to names and propositions. Aristotle apparently intended, or at
all events has given logicians in general the impression, that he
intended to analyse syllogism into propositions as premises, and
premise into names as terms. His logic therefore exhibits the curious
paradox of being an analysis of mental reasoning into linguistic
elements. The explanation is that outer speech is more obvious than
inner thought, and that grammar and poetic criticism, rhetoric and
dialectic preceded logic, and that out of those arts of language arose
the science of reasoning. The sophist Protagoras had distinguished
various kinds of sentences, and Plato had divided the sentence into
noun and verb, signifying a thing and the action of a thing.
Rhetoricians had enumerated various means of persuasion, some of which
are logical forms, e.g. probability and sign, example and enthymeme.
Among the dialecticians, Socrates had used inductive arguments to
obtain definitions as data of deductive arguments against his
opponents, and Plato had insisted on the processes of ascending to and
descending from an unconditional principle by the power of giving and
receiving argument. All these points about speech, eloquence and
argument between man and man were absorbed into Aristotle's theory of
reasoning, and in particular the grammar of the sentence consisting of
noun and verb caused the logic of the proposition consisting of
subject and predicate. At the same time, Aristotle was well aware that
the science of reasoning is no art of language and must take up a
different position towards speech as the expression of thought. In the
_Categories_ he classified names, not, however, as a grammarian by
their structure, but as a logician by their signification. In the _De
interpretatione_, having distinguished the enunciation, or
proposition, from other sentences as that in which there is truth or
falsity, he relegated the rest to rhetoric or poetry, and founded the
logic of the proposition, in which, however, he retained the
grammatical analysis into noun and verb. In the _Analytics_ he took
the final step of originating the logical analysis of the proposition
as premise into subject and predicate as terms mediated by the copula,
and analysed the syllogism into these elements. Thus did he become the
founder of the logical but linguistic analysis of reasoning as
discourse ([Greek: ho exô logos]) into propositions and terms.
Nevertheless, the deeper question remained, what is the logical but
mental analysis of reasoning itself ([Greek: ho esô logos]) into its
mental premises and conclusion?
Aristotle thus was the founder of logic as a science. But he laid too
much stress on reasoning as syllogism or deduction, and on deductive
science; and he laid too much stress on the linguistic analysis of
rational discourse into proposition and terms. These two defects remain
ingrained in technical logic to this day. But in the course of the
development of the science, logicians have endeavoured to correct those
defects, and have diverged into two schools. Some have devoted
themselves to induction from sense and experience and widened logic till
it has become a general science of inference and scientific method.
Others have devoted themselves to the mental analysis of reasoning, and
have narrowed logic into a science of conception, judgment and
reasoning. The former belong to the school of empirical logic, the
latter to the school of conceptual and formal logic. Both have started
from points which Aristotle indicated without developing them. But we
shall find that his true descendants are the empirical logicians.
Aristotle was the first of the empiricists. He consistently maintained
that sense is knowledge of particulars and the origin of scientific
knowledge of universals. In his view, sense is a congenital form of
judgment ([Greek: dynamis symphytos kritikê], _Post. An._ ii. 19); a
sensation of each of the five senses is always true of its proper
object; without sense there is no science; sense is the origin of
induction, which is the origin of deduction and science. The _Analytics_
end (_Post. An._ ii. 19) with a detailed system of empiricism, according
to which sense is the primary knowledge of particulars, memory is the
retention of a sensation, experience is the sum of many memories,
induction infers universals, and intelligence is the true apprehension
of the universal principles of science, which is rational, deductive,
demonstrative, from empirical principles.
This empirical groundwork of Aristotle's logic was accepted by the
Epicureans, who enunciated most distinctly the fundamental doctrine
that all sensations are true of their immediate objects, and falsity
begins with subsequent opinions, or what the moderns call
"interpretation." Beneath deductive logic, in the logic of Aristotle
and the canonic of the Epicureans, there already lay the basis of
empirical logic: sensory experience is the origin of all inference and
science. It remained for Francis Bacon to develop these beginnings
into a new logic of induction. He did not indeed accept the
infallibility of sense or of any other operation unaided. He thought,
rather, that every operation becomes infallible by method. Following
Aristotle in this order--sense, memory, intellect--he resolved the
whole process of induction into three ministrations:--