Handbook of the History of Logic: - Fordham University Faculty

286 Henrik Lagerlund
present in Al-Ghazālī’s Maqāsid, 17 and some interesting views on differentia and
modal propositions found in Averroes that seems to have had some influence. 18
3.1 The Logic of Al-Ghazālī
Al-Ghazālī begins the Maqāsid with a distinction between imagination (imaginatio)
and belief (credulitas). An imagination is an apprehension of a thing, he tells
us, which is signified by a single mental utterance (dictio) in the intellect. Names
like ‘stone’ or ‘tree’ etc. signify these apprehensions or imaginations. A belief is
on the other hand a sentence or a complex utterance, that is, that which says or
expresses something, like ‘the world begins’. A belief is always a composition of at
least two imaginations. The kind of knowledge, which is mediated by imagination,
is arrived at through definitions and descriptions, and the kind of knowledge, which
is mediated by belief, is arrived at through arguments. It is logic that give the
rules by which we are able to give good and true definitions and arguments. Hence
logic is the very foundation of knowledge and all science, argues Al-Ghazālī. 19
The division of logic is done to show the aim or intention of logic. 20 The aim is
to define and to prove. He gives the following fourfold division:
(3.1.1) On terms and how they signify understandings (intellectiones).
(3.1.2) On concepts (terms) and their divisions.
(3.1.3) On propositions and their composition.
(3.1.4) On proofs, which are subdivided into material and formal. 21
The major thing to note about this division is the close connection between mind
and logic. The view of logic as being about intentions is derived from Avicenna
and it was very influential. It gave rise to a major controversy between those
that argued that logic was a science of discourse (scientia sermocinalis) and those
that argued that is was a science of reason (scientia rationalis). Albert the Great
argues following Avicenna, for example, that logic is a science of mental intentions.
The first part of logic is, according to the division above, about words and
concepts. He divides his discussion about these terms into five subparts, namely:
(3:1.5) On terms signification of understandings (concepts).
(3:1.6) On terms division into simple and complex.
(3:1.7) On term division into singular and universal.
(3:1.8) On term division into verbs, names and particles.
(3:1.9) On the intention of terms.
Words signify understandings (or concepts; ‘intellectus’ in Latin) in three different
ways, argues Al-Ghazālī. First of all, a word can signify a concept directly as for
17 Parts of this has been published in Lagerlund [forthcoming].
18 I have written about the modal part previously in Lagerlund [2000].
19 See Al-Ghazālī, Tractatus de logica, 239, 6-13.
20 Al-Ghazālī, Tractatus de logica, 242, 100-102.
21 Al-Ghazālī, Tractatus de logica, 243, 115-120.