Handbook of the History of Logic: - Fordham University Faculty

The Assimilation of Aristotelian and Arabic Logic up to the Later Thirteenth Century 339
Consequence,
Non causa ut causa,
Many qustions as one.
Many of these are further subdivided into different cases. Most of the fallacies
in this list are well known and I will not go through them all here. Peter’s and
William’s discussions are very detailed. The fallacy of equivocation occurs when
a word (name) has diverse signification and this is not realised, as for example
in: ‘Every dog runs, one of the heavenly constellations is a dog; therefore one
of the heavenly constellations runs’. Amphibology is the diversity of judgement
based on the unity of expression, as when one argues that: ‘Whoever ploughs the
seashore moves sand, this man is ploughing the seashore (that is, indicating that
he is working in vain); therefore this man moves sand’.
The non-linguistic fallacy of accident is said to occur when something is attributed
to a thing as a subject and subsequently also attributed to an accident.
An example would be when it is argued that: ‘Socrates is esteemed by you, but
Socrates is your father’s murderer; therefore your father’s murderer is esteemed by
you’. The fallacy of begging the question (“petitio principii”) occurs for example
when the thing to be proved is assumed as a premise. The fallacy of treating what
is not a cause as a cause occurs when in some cases when a syllogism leads to an
impossibility, because something impossible follows one of the premises is rejected
on the grounds that it was the cause of the impossibility (although it was not).
Much more could be said about these fallacies, but I will leave it at this. 94
5.2 The Syncategoremata
Among the textbook authors there seem to be a general agreement that there are
two branches of the logica moderna, namely the properties of terms (‘propreitates
terminorum’) and an account of the function of syncategorematic terms (‘syncategoremata’).
These two branches are supposed to be theoretically exhaustive of the
kinds of terms occurring in various roles in propositions. The first part was dealt
with in the textbooks of logic we have seen above, but the second part was usually
given a separate treatment in books devoted to the syncategorematic terms. Both
Peter of Spain and William of Sherwood wrote such treatises. 95 I will here give
an outline of the content of these works.
The division and content of the chapters of William’s work is the following:
(1) ‘Every’ or ‘All’ (Omnis)
(2) ‘Whole’ (totum)
(3) Number words (Dictiones numerales)
(4) ‘Infinitely many’ (Infinita in plurali)
94See [Ebbesen, 1981b] for the history of the discussions of fallacies. See also [Grabman, 1940]
and [Pironet, 2005].
95The discussion of syncategorematic terms was absorbed into the Sophismata treatises in later
medieval logic. See [Pironet, 2005].