Dialectic, unlike logic, is concerned with particular individuals with whom we are engaged with in argument. The argument proceeds by agreed premises that are intelligible to all people engaged in the dialectical argument.
Aristotle defines two forms of intelligibility: the qualified and the unqualified. Intelligibility is qualified when the information being transmitted is intelligible to a particular person. It is unqualified when it is objectively intelligible. In logic, intelligibility needs to be unqualified. In dialectic, intelligibility can be either qualified or unqualified.
Dialectic is a pedagogic exercise and therefore is concerned with both unqualified intelligibility and qualified intelligibility. It matters that the information can be understood by the person it is being presented to. Indeed, the aim of dialectic is to work with a particular person in moving from qualified intelligibility (what they already understand) towards unqualified or absolute intelligibility (what can be demonstrated through skillful use of logic).
Dr Evans argues that the aim of dialectic is to “start from what we understand and move towards what is absolutely intelligible.” (87) This means that “Aristotle is concerned with the concepts of intelligibility not only in their absolute [unqualified] form ... but in their qualified form ... He elects to treat these concepts in their full complexity”.
Further: “[T]he technique by which intellectual advance is produced must recognise intelligibility in both its forms, the qualified and the unqualified, and since dialectic is this technique the recognition of these two forms of intelligibility are essential to dialectic” (93).
This is not the case with logic, which is concerned with identifying absolute truth irrespective of whether that truth is understood by any one individual, or indeed as readers of Hegel may understand even if it is not intelligible to almost anyone.
In logic, the concern is only with unqualified intelligibility. Logic is a science in pursuit of truth and validity, and if its findings cannot be explained to a particular interlocutor this does not define its success or failure.
A further, related, differentiation is that an objective of logic is to arrive at a singular, absolute definition when describing any object. However, for Aristotle dialectic can allow for multiple and contested definitions. If the use of a definition which is not absolutely valid can advance an argument, and through that the instruction of a particular person, then this can be admitted in dialectic, which is not the case for logic.
Dr Evans presents Aristotle’s argument like this: ”[T]he definition - the proper or real definition - is that which proceeds in terms of the absolutely more intelligible and provides us with the unqualified object of understanding; but an account which proceeds in terms of what is more intelligible only to some particular person or group of people and provides them with objects only of their understanding, is not to be denied the title of definition, albeit definition qualified by reference to those whom it instructs ... He consistently maintains that the proper course in conducting an investigation is to start from what is more intelligible to us, but less intelligible absolutely, and proceed to what is more intelligible absolutely, but (before we start the investigation) less intelligible to us.” (68/69)
Dialectic is therefore concerned with individuals, and the actual practice of dialectic can vary considerably depending on the individuals involved. This might include considerations of such characteristics as the age and ability of each participant as dialecticians.
The arguments used must be intelligible to the other person. Aristotle suggests using syllogisms (or deduction) when engaged with an experienced dialectician, and induction when speaking with less experienced people.
Dr Evans: “Aristotle ... recommends the use of induction against the many and of syllogism against the expert in dialectic ... He distinguishes the various procedures one should follow in gymnastic dialectic according to the age and experience of one's opponent, and goes on to justify the distinction by reference to the general aims of this form of dialectic.”
Finally, Aristotle warns against attempts to use dialectical argument against those who are not practiced in it: “[H]e warns those who seek to be trained in dialectic to avoid chance dialectical encounters, on the grounds that these are likely to be conducted in a contentious spirit and be unsatisfactory as pieces of argument” (91).
Dialectic considers the individual to the extent that it should not even be practiced with the wrong type of individual, whereas logic does not need to be practiced with any other person and should not be concerned by what is accepted as true or even understood by any other person.
The second - and equally important - differentia between the art of dialectic and the science of logic is the material that one can use - the choice of premises - in presenting arguments.
Logic requires that premises are primary and true in absolute terms, or are themselves conclusions of logical argument which begin with what is primary and true. The test for dialectic is different: we can use premises which are plausible.
Aristotle states: “[If] one wrests one’s conclusion from premises which are as endoxic as possible, his dialectic is good.” (92). Dr Evans argues that Aristotle is consistent across a wide number of texts - from the Metaphysics to Topics - “in making plausible views (endoxa) the starting point in dialectic”. (38). He adds later, “a notion which is central to dialectic is that of the exdoxon” (78).
Aristotle gives a clear definition of what counts as endoxic premises, those which are permissible for dialectical discussion. These are propositions that “seem [valid] to all or to most or to the savants (sophoi), and of these either to all or to most or to the most understanding (gnorimoi) and view-holding (endoxoi)” (79).
Endoxa are statements which seem plausible either to everyone, or to most people, or to those who are most wise. Endoxa can be unqualified - plausible to everyone, even if not proven - and also qualified - plausible only to a particular audience.
Dialectic and logic both rely on the syllogism to move from premise to conclusion. The difference is that logic can only use premises which are true whereas dialectic can use premises which are endoxa, or plausible to right thinking people.
Dr Evans explains: “Aristotle defines the dialectical syllogism as one which takes its start from the endoxa, in contrast to the demonstrative syllogism which takes its start from what is primary and true” (78).
In using endoxa, it is important to remain alive to the fact that the qualified nature of the premises will impact on the quality of any conclusions, which will also be qualified. True premises and sound logic should provide true premises. However, plausible premises admitted in dialectic can only provide plausible conclusions.
It may also be inferred that premises that are only plausible to a limited audience - say, the savants rather than everybody - are likely only to provide argument and conclusions that are compelling to that same audience.
Dr Evans further points out: [W]ith his notion of the unqualifiedly endoxic… [Aristotle] is attempting to allow for a distinction between the area of dialectical debate in which we recognise the distinct authorship of the various views and adhere to the limitations which this imposes on the discussion, and the areas where we are concerned with the absolute plausibility of the thesis under discussion”. (83).
The introduction of the concept of plausibility necessitates an understanding of the spectrum from absolutely plausible to the absolutely implausible - from views that are convincing to everyone to those that would not be accepted by anyone.
Aristotle in accepting which views are possible for inclusion in dialectical discussion is a pragmatist - discounting both the absolutely plausible and the absolutely implausible from dialectic. The objective of dialectic is to test the plausibility of arguments, and this can be achieved by taking a premise and then through argument invalidating it by linking it through syllogism to an implausible conclusion.
Aristotle “is a realist to the extent of recognising that there are some views...which do not need to be considered because of their absolute implausibility. He further agrees with the realist in recognising that this concept of absolute plausibility, and in recognising that this concept is essential to dialectic insofar as the final aim of dialectic is to force one's opponent to say something as implausible (absolutely) as possible. But he agrees with the relativist in recognising the need to start from the views which are already available and to observe carefully, as we examine them, the particular character of each.” (85)
We have come to the end of our attempt to define Aristotle’s dialectic, in a way which is useful and intelligible.
We note that dialectic belongs to the genus of intellectual activity or expertise. It sits in the sub-genus of the arts, along with medicine and rhetoric, as it deals with qualified premises and conclusions - its success relates to individual human beings.
It is therefore differentiated from the sciences - logic and mathematics - which are unqualified or absolute in presenting arguments that are universal and do not relate to any individuals or groups of individuals. The logician seeks to validate argument, not to persuade a person of the validity of any argument. Logical conclusions do not have to be understood by any one person.
We have discovered the essence of dialectic by comparison to logic, and found that the aim of dialectic is pedagogic - in transferring information from the expert to the inexpert - where with logic the aim is to establish absolute truth.
We have established that Aristotle argued that dialectic can include endoxa - plausible arguments - whereas logic is limited to absolute truth. We have, in achieving this, provided a dialectical definition of dialectic. This has been achieved through a close reading of Dr John D G Evans’ Aristotle’s Concept of Dialectic.
Dialectic requires the use and deployment of logic. We now turn to a definition and working explanation of Aristotle’s logic.
Brendan Montague is editor of The Ecologist. This article is part of the Endoxa.review project.
Page references given refer to J. D. G Evans, Aristotle’s Concept of the Dialectic (Cambridge: Cambridge University Press, 1978).