Diocles of Carystus on the method of dietetics 79
apparent tension involved with his belonging to the ‘Dogmatist’ tradition,
later on.
The first claim that Diocles attacks is that ‘substances’^12 that have sim-
ilar qualities have the same powers. I use the word ‘quality’ to refer to
characteristics such as those mentioned in section 5 – being juicy or dry,
having a particular smell, having a certain degree of hotness – although
the Greek text has no separate term to denote this category. ‘Power’ is used
fordunamis, which is the power to produce a certain effect in the body
of the consumer (examples mentioned in the text are ‘provoking urine’
and ‘laxative’ in section 6 and ‘nutritive’ in section 8 ). This distinction will
concern us later on. It is important to note that the claim Diocles criticises
does not explicitly say that there is a causal connection between having a
certain quality and having a certain power: it just states the combination
of the two. Yet even this is shown by Diocles to be wrong on empirical
grounds; he refutes the claim by means of a ‘judgement based on experi-
ence’ (a
"3 , to use the words with which Galen introduces
the quotation from his work) by pointing out that not all substances that
are similar in respect of having a certain quality, say, A (section 5 : ‘similar in
these respects’,2) )), produce results that indicate the presence
of a certain power, say, B.^13
In section 6 this is immediately followed by the denial of a second claim,
which Diocles does not explicitly put in the mouth of the same group,
but which he presents as a consequence of the first claim (‘and indeed,
one should also not...’,(. ). This consequence is easy to see. For
claim one does not say, but by its wording at least suggests, that there is a
causal connection between having a particular quality and the possession of
a particular power. This connection may take various forms: for instance,
sweetness may be the cause of being laxative; or (perhaps less likely) being
laxative may be the cause of being sweet; or, thirdly, sweetness and being
laxative may both be results or effects of an underlying cause (in which
case sweetness could be regarded as a sign of being laxative). Diocles only
mentions the first of these possible consequences – which is also the most
obvious – and he refutes it by means of the same empirical evidence he
adduced against the first claim: experience shows that not all things that
have the same quality have the same powers.
(^12) Throughout the fragment, Diocles’ Greek does not specify what we have to think about; Galen’s text
suggests that ‘foodstuffs’ ( 0
0 ) are meant (see section 12 ), but drinksK! )
and possibly also drugsK ) may also be included. [Hence I have now preferred ‘substances’
over the ‘foodstuffs’ of my ( 1996 ) translation.] Jaeger translates ‘Dinge’ or ‘Mittel’, Torraca ‘sostanze’,
Smith ‘foods’.
(^13) Diocles’ refutation ignores the possibility that a foodstuff may have a particular power but does not
actualise it in a certain case (on this possibility cf. Aristotle,Metaph. 1071 b 19 , 23 ).