Over the past two decades, Ray Jackendoff has persistently tackled difficult issues in the theory of mind and related theories of cognitive processing. Chief among his contributions is a formal theory that elaborates the nature of language and its relationship to a broad set of other domains. Languages of the Mind provides convenient access to Jackendoff's work over the past five years on the nature of mental representations in a variety of cognitive domains, in the context of a detailed theory of the level of conceptual structure developed in his earlier books Semantics and Cognition and Consciousness and the Computational Mind . The first two chapters summarize the theory of levels of mental representation ("languages of the mind") and their relationships to each other and show how conceptual structure can be approached along lines familiar from syntactic and phonological theory. From this background, subsequent chapters develop issues in word learning (and its pertinence to the Piaget-Chomsky debate) and the relation of conceptual structure to the understanding of physical space. Further chapters apply the theory to domains outside of traditional cognitive science. They include an approach to social and cultural cognition modeled on first principles of linguistic theory, the beginnings of a formal description of psychodynamic phenomena, and a discussion of musical parsing and its relation to musical affect that bears on current disputes in linguistic parsing. The final chapter takes up a long-standing conflict between philosophical and psychological approaches to the study of mind, arguing that mental representations should be regarded purely in terms of the combinatorial organization of brain states, and that the philosophical insistence on the intentionality of mental states should be abandoned.
I've always regarded Ray Jackendoff as an anti-Chomsky Chomskian. Like Chomsky he believes in innate structure but unlike Chomsky he uses meaning rather than parts of speech to formulate his arguments. He also sits a bit uncomfortably, particularly in chapters 5 and 8, on the fence between philosophical and and psychological linguistics, which does make for good discussion. The language used in the book is not heavily laid with jargon though Jackendoff can be wordy and the level of presentation is aimed at an academic rather than a popular audience.
"Languages" consists of 8 essays, some revised just for the book, which argue for the existence of underlying more primitive representations for thought. In chapters 2 and 3 Jackendoff reflects on the idea of concept, expressing his own approach and comparing it to Chomsky, Piaget and Fodor. He regards concepts as partially innate, partially learned and notes analogies of inference in different domains such as in ownership and spatial reasoning. Chapter 4 asks if there is a separate facility for social cognition and if so what are it's features and components. Aspects considered include face recognition, ideas of social structure and the differences between an internal (i-language/i-social) representations and external (e-language/e-social) verbalization; the ideas of transaction, ownership and property rights are considered - the transmission of ideas taken as a special case as transferring an idea does not entail loss of ownership by the giver.
Chapter6 "Spatial Language and Spatial Cognition" is a comprehensive look at the limited number of English terms referring to the placement and orientation of objects and finds that with some differences other languages have more or less the same descriptive power. The completeness allowed by the small number of words makes this analysis more into a scientific analysis than philosophic discussion. There is a mismatch between language's ability to describe and visual cognition suggesting that different representations are at play. Chapter 7 "Musical Parsing and Musical Affect" promised to do the same for music. Alas, I'm a bit of an illiterate when it comes to recognizing and labeling musical patterns. I found the theorizing about internal musical parsers interesting but I didn't follow all of the specific examples - one of my limitations and your mileage may vary.
Jackendoff is one of the great lights of modern linguistics. Readers should find that this book to be a reasonable exposure to his ideas. He also makes frequent references to Miller & Johnson-Laird's 1976 classic Language and Perception, a favorite of mine, which treated the ontology of language as a systematic program of observation and categorization rather than a series of anecdotes to support a theory of mind.