by Scott F. Aikin and Robert B. Talisse
Ernie: “Is it possible you'll be around after lunch for a quick chat?”
Ernie: “Ok. I'll see you then.”
Bert: “Wait, wait! I didn't say I'd be around after lunch!”
Ernie: “What the heck?!?!”
This is a case of a conversational misfire, and although errors of this kind are the central ingredients of the humor of people like Woody Allen, Larry David, and Lewis Carroll, such misfires can create a good deal of argumentative and philosophical confusion. Let's start with a quick diagnosis of the misfire above, then we'll identify why this kind of misfire is common. We'll finish by pointing to a few philosophical lessons.
The core of the error above lies in this: Bert assents to the (mere) possibility of being around after lunch for a meeting with Ernie. Assenting to the possibility of a meeting is not assenting to the actuality of a meeting. Consequently, Bert thinks that his assent to the possibility of a meeting does not place him on the hook for attending any actual meeting. And so, from this perspective, Ernie has made a modal error; he has fallaciously inferred actuality from possibility. Among philosophers, that's a rookie's mistake.
Yet it seems that Ernie is well within his rights to respond with incredulity at Bert's final response. Even though Bert is correct about the modal relation between possibility and actuality, Bert is nevertheless being obtuse, and it's perfectly reasonable for Ernie to respond with exasperation. To diagnose the misfire simply as the result of Ernie's modal confusion leaves unexplained why Ernie so readily commits the inference and why it seems that Bert is obtuse not to recognize it. Note that it also fails to capture what is mildly humorous about the exchange.
In order to get a better sense of what's going on, we must look beyond the semantics of Bert's assertions, and attend to the pragmatics of Ernie and Bert's exchange. To explain, semantics is an account of the truth-functional and formal properties of sentences and assertions, while pragmatics is an account of the uses to which sentences and assertions are put within contexts of communication. Given that the case we are interested in is a conversational exchange of sentences, we need to look at both Bert and Ernie's contributions.