Sign language reveals the hidden logical structure, and limitations, of spoken language

The study, published inTheoretical Linguisticswith nine peer-commentaries, is the culmination of more than eight years of research on French Sign Language and American Sign Language (ASL) by Philippe Schlenker, a senior researcher at Institut Jean-Nicod within France's National Center for Scientific Research (CNRS) and a Global Distinguished Professor at New York University.

Sign languages are considered by linguists as full-fledged and grammatically very sophisticated languages, which are essential to the communication of Deaf people. But they also have unique insights to offer on how meaning works in language in general. In several cases, they make visible a logical structure that must be inferred indirectly in spoken language.

For instance, the logical structure of the English sentenceSarkozy told Obama that he would be electedis conveyed more transparently in sign language.The English sentence is ambiguous, Schlenker explains, ashecan refer to Sarkozy or to Obama. Linguists have postulated that this is because the sentence contains some unpronounced -- but cognitively real -- logical variables likex一个ndy.

If the sentence is understood asSarkozy_xtold Obama_ythat he_xwould be elected,with the same variablexonSarkozy一个nd onhe, the pronoun refers to Sarkozy; if insteadhecarries the variabley(=he_y), it refers to Obama. Remarkably, in sign language the variablesx一个ndycan be visibly realized by positions in space, e.g. by signingSarkozyon the left andObamaon the right. The pronounheis realized by index pointing. If it points towards the left, it refers to Sarkozy; if it points towards the right, it refers to Obama: left and right are the visible realization of the unpronounced variablesx一个ndy.

But sign languages don't just reveal the hidden logical structure of spoken language: they also highlight some of its limitations. While some spoken words can be iconically modulated to resemble what they refer to (think of the wordlooooooongto mean 'very long'), this is a rare occurrence.

"By contrast, iconic modulations are entirely common in sign language," Schlenker observes. He points to the ASL verb for 'grow' (as inmy group has been growing), which may be signed with broader endpoints to denote a larger growth, and may realized more quickly to represent a quicker growth.

"One and the same expression may simultaneously be logical and iconic, as is the case with pronouns," adds Schlenker, who has previously published work co-authored with Deaf consultants and researchers. "If referring to a very tall individual standing, one can point upwards because the head of the person is high; but if the tall person is hanging upside down, one will pointdownwardsinstead: the logical variable has a dual life as a simplified picture of the person it denotes."

“在一些维度,符号语言更前pressive than spoken language because they combine the same kind of logical resources with far richer iconic means," he concludes. "They are, in a sense, 'super languages' -- and they have a unique contribution to make to our understanding of human meaning."