classes of counter arguments

pkn.html

@@ -520,11 +520,18 @@ <h3>PKN and RDF</h3>
   <h2>Plausible Reasoning and Argumentation</h2>
 
   <p>Plausible reasoning is about generating arguments that support or counter a premise, gathering information along the way. The reasoning process is driven by a queue of premises awaiting consideration, plus a record of reasoning so far, which can be modelled as a reasoning graph. The reasoner applies heuristics (strategies and tactics) to determine which potential inferences to apply and in what order to develop the arguments. As reasoning proceeds, the consideration of additional evidence may either strengthen or weaken earlier conclusions.</p>
+  <p>Guidelines for effective arguments have been studied by a long line of philosphers all the way back to Ancient Greece, e.g. work by Carneades and Arstotle on classical rhetorical approaches, e.g. <em>ethos</em> (credibility), <em>pathos</em> (emotion), <em>logos</em> (logic), <em>kairos</em> (opportune) together withrhetorical questions.</p>
 
   <section id="explanations">
     <h3>Generating Explanations</h3>
     <p>The inference engine can start with the premise in question and  look for direct evidence, and after that, indirect evidence involving inferences using different kinds of PKN statements that pose intermediate premises for consideration. The reasoning process generates a graph that starts from the premises and works back to direct evidence in the knowledge graph. The reasoning graph can then be scanned in the reverse direction to generate explanations that start with the facts and progressively justify the premise via a series of inferences.</p>
     <p>The reasoning process can try to support an argument via finding additional evidence, or it can try to generate counter arguments that undermine, undercut or rebut other arguments. The explanation then needs to put these arguments into context using the appropriate templates.</p>
+    <p>Counter arguments can be classified into three groups:</p>
+<ul>
+    <li><strong>undermining</strong> another argument when the conclusions of the former contradict premises of the latter.</li>
+    <li><strong>undercutting</strong> another argument by casting doubt on the link between the premises and conclusions of the latter argument.</li>
+    <li><strong>rebutting</strong> another argument when their respective conclusions can be shown to be contradictory.</li>
+</ul>
   </section>  
 
   <section id="certainty">