Theodore Dalrymple is one of my favourite writers.  He is perhaps most well known for his descriptions of the lurid depravities of underclasses, both social and intellectual.  Equally obvious are his scathing opinions and dry wit.  For afficionados of argumentation, however, his writing also appeals due to his skillful deployment of crisp and often complex chains of reasoning.  Here is a glimpse of Dalrymple doing his thing:

“Abbott was on the run for a short while, but then returned to prison where, about twenty years later, he hanged himself. In his only other book, called My Return, he argued that he could not have intended to kill the young waiter, because he stabbed him only once, and a man like him would have stabbed him many times had he intended to kill him. This was not the argument of a good man.”

Diagrammed in Rationale, the central argument looks like this:


Note how the two premises “work together,” and the diagram represents this by “enveloping” both premises in the same green area – which is really just an extension of the line connecting the premises to the main contention, the claim that he could not have intended to kill the young waiter.

Dalrymple’s confident control of the fundamentals of good reasoning is evident in the way he has laid out three claims which, in the way they are worded, display their tight interconnectedness.   Put another way, the three claims comprise a simple argument observing almost to the letter some basic principles of informal argument structure

The argument is an example of a classic form known by logicians as modus tollens.  In Rationale’s template section, we find a schematic version of modus tollens:

Modus Tollens

Dalrymple’s argument, massaged so as to more exactly fit the modus tollens template, looks like this:

Stabbing Modus Tollens version

And with that, I promise that not all entries in this blog will end up like lecture notes for an introductory reasoning class!