Summer Institute in Cognitive Science 2010: The Origins of Language - UQUAM June 27, 2010 Dan Sperber www.dan.sperber.fr Pragmatic insights Pragmatic insights on the evolution of language evolution of language on the
Collaborators: Deirdre Wilson Gloria Origgi
Two models of communication • The code model • The inferential model
The code model • A code is a set of <signal, message> pairs • Communication is achieved by the communicator encoding a message into a signal and the receiver decoding the signal back into the message
message encoding signal decoding message
The code model of linguistic communication • A human language is a complex code, the <sound, meaning> pairs of which are sentences generated by a grammar with recursive capacities and a rich lexicon • Linguistic communication consist in a speaker encoding her meaning into the sound structure paired with it in the language, and in the hearer retrieving this meaning through decoding
meaning encoding utterance decoding meaning
The proximal function of language • For the code model: To provide the means for the speaker to encode her meaning into an utterance and for the addressee to decode this utterance
The bootstrapping problem in explaining the evolution of language
Two types of adaptations • Hetero-adaptations • Homo-adaptations
Hetero-adaptations • Hetero-adaptations are adaptations to an aspect of the environment that predated the adaptation • Most specialized cognitive abilities have a specific domain of information available in the environment well before the ability develops. They are adaptations to this aspect of the environment. Examples : – 3D perception – Detection of a given kind of predator
Homo-adaptations Some specialized cognitive abilities have a domain of information that is initially empty and that gets filled only by the behavior of individuals already equipped with this ability. Examples: – Cognitive bases of reciprocal altruism – biologically evolved signals – language faculty
A possible explanation of the emergence of homo-adaptations – Every homo-adaptation starts as a side-effect of an other adaptation, or is neutral enough not to be selected out. – It becomes positively selected as an homo- adaptation when the offsprings of the initial mutant are sufficiently numerous to benefit from the trait in their interactions
The biological evolution of codes Compare: • The emergence one by one of atomic signals, each conveying a complete message • The evolution of a repertoire of signals into a system of complex expressions
Moreover, in the case of language, • what has biologically evolved is not a language, but the ability to learn a language (a ‘language faculty’) • it is not enough to have a sufficient number of people sharing such an ability for them to find in their environment a language to acquire
With the code model, • Coded communication works best when the interlocutors share exactly the same code • Differences in the codes of the communicators typically cause failures in communication • The biological or cultural emergence of codes must secure their quasi-identity across communicators
• A change in the language faculty of an individual either will be without effect on languages, or will cause her to acquire a language different from that of others on the basis the same linguistic evidence • If the code model of linguistic communication is right, this mismatch between languages will impair the individual’s abililty to communicate. It will be anti-adaptive.
• A change in the language faculty of an individual either will be without effect on languages, or will cause her to acquire a language different from that of others on the basis the same linguistic evidence • If the code model of linguistic communication is right, this mismatch between languages will impair the individual’s ability to communicate. It will be anti-adaptive.
With the code model, • The evolution of small repertoires of signals is not too hard to understand. • The evolution of a capacity to acquire culturally variable systems with a rich lexicon and complex syntax is quite paradoxical
Anyhow, is linguistic communication a matter of coding and decoding? • Human languages are incomparably richer than the codes of other animals both syntactically and lexically • Human languages are grossly defective qua codes: sentences massively underdetermine their interpretation.
Examples - It is late - Henry’s car is too big - I have eaten
Two models of communication • The code model • The inferential model
The inferential model • In inferential communication, the communicator helps the addressee by giving evidence of her meaning and the adressee infers the meaning from this evidence and the context • Anything can serve as evidence provided meaning can be inferred from it Example : • – Peter : Do you want to come for a walk? – Mary hold up the book she is reading
Communicative behaviour environment memory perception perception contextual information Pragmatic inference communicator’s meaning
What kind of inference? • A communicator’s meaning is a complex intention (Grice) • Understanding such meaning consists in inferring a mental state of the communicator • It is a special case of ToM or ‘mindreading’ inference
Peter : Do you want to come for a walk? Mary hold up the book she is reading Peter must infer that, in ostensively holding up her book, Mary has 1.The communicative intention to inform Peter of her informative intention, 2.the informative intention to inform Peter that she wants to go on reading rather than go for a walk
The inferential model of linguistic communication • The speaker helps the addressee by giving as evidence of her meaning an utterance and the adressee infers the speaker’s meaning from this utterance – and in particular its semantic properties – and the context Example : • – Peter : Do you want to come for a walk? – Mary: I want to read
utterance environment Perception and linguistic decoding memory perception semantic structure contextual information Pragmatic inference speaker’s meaning
Peter : Do you want to come for a walk? Mary: I want to read Peter must infer that, in saying “I want to read,” Mary has 1.The communicative intention to inform Peter of her informative intention, 2.the informative intention to inform Peter that she wants to go on reading rather than go for a walk
The proximal function of language • For the code model: To provide the means for the speaker to encode her meaning into an utterance and for the addressee to decode this utterance • For the inferential model: to provide the means for encoding precise and structured evidence of the speaker’s meaning
Inferential communication is an exploitation of mindreading and hence can only evolve in a species capable of mindreading
The evolution of mindreading Facts: • Other primates (chimpanzees in particular) have at most rudiments of a mindreading • Modern humans are virtuoso mindreaders Questions: • Is mindreading an evolved adaptation or an acquired skill? • If an evolved adaptation, what drove its evolution? Standard hypothesis: The evolution of metarepresentational ability was driven by • selection for social competence (“Machiavellian intelligence hypothesis”)
A mindreading ability does not have communication as a primary function, but it makes inferential communication possible
Inferential comprehension • More complex inference than ordinary mindreading • But the communicator helps the addressee read her mind • Hence, possibly specific, relevance-based heuristics • A distinct adaptation?
With the inferential model… • For communication to succeed, it is not necessary that the communicator and the addressee decode the sentence uttered in exactly the same way • It is enough that they see the utterance, however decoded, as evidence for the same conclusion regarding the speaker’s meaning.
Examples: Peter : I am exhausted Mary : Then let’s go home Your glass is full! Don’t you like Chardonnay? Peter : I love you! Mary : I love you too!
With the inferential model… • A richer decoding of linguistic evidence may actually facilitate inference • A language faculty that leads to the acquisition of a grammar that attributes to utterances more structure than they superficially realize may be advantageous
Unexpressed constituants Atomic symbols: “drink”, “water” Language: S NP VP V NP «water»
Unexpressed constituants Atomic symbols: “drink”, “water” Language: S NP VP V NP water
Unexpressed constituants Atomic symbols: “drink”, “water”
Unexpressed constituants Atomic symbols: “drink”, “water” Language: S NP VP V NP drink water
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