Single Review on past events

What is logic? – Surely a question with many answers, as a mathematician would define it different as a philosopher or a psychologist. Asking Wikipedia, logic is “the study of modes of reasoning (which are valid and which are fallacious)”. And reasoning – as studied by logic – means reasoning by humans, and specifically verbal reasoning. According to this, Irene Heim, professor of linguistics and one of the most renowned scholars working on the semantics of natural languages, argues that logic is more specifically a part of linguistics, namely the study of the human language faculty. This view contrasts with a normative conception of logic (common among both lay people and philosophers), according to which logic is less about people's actual reasoning than about how they should reason.  

In her Jour Fixe lecture on 15 November Irene Heim presented several examples to illustrate the contrast between normative logic and logic as cognitive science. For example, a normative logician might say that “John has a dog or a cat” does not entail that “John doesn´t both have a dog and a cat”, not caring to explain why ordinary people typically do draw this inference. Logicians as psychologists, but contrast,  take such observations seriously.  They elaborate their formal models accordingly and unravel the deeper logic behind the supposedly “illogical” behavior.

Irene Heim explained: “The validity of inferences depends on their form, not on the particular subject matter of the premisses and conclusion.” She illustrated various inference schemata and the logical forms of their premisses and conclusions: “If A, then B”, or “All B are A”, or “A is B-er than C”. Crucial, according to the Senior Fellow, is that logical forms have a hierarchical structure. The words and symbols in logical forms are not just chained together in a string; they are grouped together into larger and larger units. But although people think in logical forms when reasoning it is important to consider that they mostly communicate in acoustic signals. In order that this communication works successfully, an acoustic signal has to determine – or at least give sufficient clues about – the intended logical from. Of course, and that´s what some auditors objected as well, you have to consider the context in which a sentence is said. Many sentences have more than one logical form or ambiguous meanings. For example: The premiss is “Mary met Ann in her tent”. The conclusion is “Ann had a tent”. But it can also be that “Mary had a tent”.

Finally Irene Heim elucidated displacement as the most dramatic respect in which logical forms can differ from the spoken sentences that convey them. Again an example: Premiss 1: “Mary hates every professor”. Premiss 2: “Socrates is a professor”. Conclusion: “Mary hates Socrates”. This illustrates a major shortcoming of traditional conceptions of logical form, which prevailed from the time of Aristotle into the 20th century. It shows that the relation between spoken or written texts and their logical forms can be opaque. Nevertheless that´s what makes languages and communication interesting and linguistics an exciting science.

At the end of her talk Irene Heim gave a glimpse at her current research on logical form, in which she cooperates with Doris Penka.