Iryna Khomenko
Taras Shevchenko National University of Kyiv,
Ukraine
INFORMAL LOGIC AND EPISTEMOLOGY
In my talk I would like to focus on the interrelation between informal logic and epistemology, and in particular consider the problem of assessment criteria for an argument.
I start with briefly outlining some key definitions of informal logic with an aim to answer the question whether informal logic has any right to claim its place in logic in general.
Then I will compare two approaches to an argument. The first one can be characterized by the notion of an argument as an inferential structure (premisesconclusion/claim-reason complex). In this case a reason-giving argument and criteria of its appraisal are argued to be a matter of formal logic. Within the second approach an argument can be studied as a form of a dialogical interaction and called a disputing argument. Respectively the assessment criteria of such argument are considered to be part of informal logic.
Next step would be to reflect on a question what criteria can be used to determine a good argument in logic. Unfortunately no consensus has been reached so far in terms of defining the notion of such argument. At the same time the point of view highlighting inadequacy of formal logic as a tool for evaluating naturallanguage arguments is wide spread and recognized within informal logic.
Speaking of such criteria within formal logic I will refer to “soundness” and
“validity”. According to these criteria an argument is good if and only if it is formally valid and its premises are true. The fact that by following these criteria all the good arguments are being reduced to deductive ones proves how strong they are.
In order to avoid such restriction informal logicians developed other assessment of arguments. For instance, a triad of acceptability, relevance and sufficiency is often used as a popular set of criteria in this regard. To be considered

as a good argument, its premises of an argument must be acceptable, relevant to the conclusion and sufficient to support it.
Finally I want to draw attention to the main differences between formal and informal criteria of good argument. The main question in this regard is whether informal criteria should be considered as logical or epistemological (since they may be explicated in terms of justification, which is one of the key epistemological concepts).
I will conclude with listing arguments for and against the claim that informal logic can be considered as applied epistemology.