This is the context for the books reviewed here. Both Steven Pinker, a psychologist, and Mark Johnson, a philosopher, explicitly acknowledge that their ideas on human communication, aesthetics and understanding must be compatible with what is known about brain function. As Johnson says, neuroscience can ‘suggest plausible constructive hypotheses about the nature of mind, thought and language’. If their books aim to provide new insights into human nature, the books by Giacomo Rizzolatti and Corrado Sinigaglia, and by Marco Iacoboni, take us into the minds of the scientists generating the observations that underpin these new ground rules.

Pinker is best known for two previous books, The Language Instinct: How the Mind Creates Language (1994) and The Blank Slate: The Modern Denial of Human Nature (2002), written with a witty yet rigorous style that ensured wide popular and professional readership. His latest book, The Stuff of Thought: Language as a Window into Human Nature (Allen Lane, $59.95 hb, 500 pp), skilfully unites his interests in language and human nature. Its basic premise is stated clearly in the preface: ‘A close look at our speech – our conversations, our jokes, our curses, our legal disputes, the names we give our babies – can ... give us insight into who we are.’

The first four chapters establish Pinker’s linguistic framework. Beginning with problems that children must solve to learn a language, Pinker explores the nature of nouns and their adjectives, especially the vexing issue of polysemy: words with several distinct but related senses. The distinctions may be subtle. For example, ‘a sad movie makes you sad, but a sad person already is sad’. However, they are probably encoded differentially in the brain’s language centres. Pinker concludes, therefore, that ‘words are not the same as thoughts’. Indeed, ‘much of human wisdom consists of not mistaking one for the other’. Pinker then considers verbs and their links to time and space via tense and prepositions, leading to an extended discussion of ‘the semantics of causation’. Critically, language is full of ‘verbs that express causal concepts nakedly’, as in ‘I am writing this article’. These semantic elements ‘are gadgets in the brain, rather than readouts of reality’, yet they give us the vocabulary to ‘reason about the physical and social world’.

If language does not accurately reflect our thoughts or physical reality, how do we ever develop, let alone communicate, complex ideas and concepts? Pinker’s solution partly lies in our pervasive use of metaphor. He does not take a position as extreme as George Lakoff, who claims that nearly all verbal knowledge is derived from a small set of metaphors of how our body moves through space and time. Nevertheless, Pinker concludes that ‘metaphor really is a key to explaining thought and language ... Our powers of analogy allow us to apply ancient neural structures to newfound subject matter, to discover hidden laws and systems in nature, and, not least, to amplify the expressive power of language itself.’

The second part of Pinker’s book shifts focus from the structure of language itself to everyday problems of communication. Why do we not have specific words for some very clear ideas: for example, one’s adult children? Why do some neologisms gain rapid currency (such as blog) while others never survive? Why is your own name so important? Pinker argues convincingly that the answer lies within the unpredictable ebbs and flows of fashion. Consequently, a person’s name ‘connects us to society in a way that encapsulates the great contradictions in human social life: between the desire to fit in and the desire to be unique’.

One startling revelation of modern neuroscience is the biological basis of swearing: specific brain circuitry responds to and generates swearing, independently of normal grammatical speech. There are strange things going on here. In an entertaining chapter, ‘The Seven Words You Can’t Say on Television’, Pinker writes, ‘For many people, excrement has a far more unpleasant connotation than shit ... Nonetheless, shit is less acceptable than excrement.’ And if we all know what we mean by the ‘F-word’, why does the feeling change if I actually use the fucking thing? For once, Pinker himself seems at a loss for a clear explanation. Finally, he sides with Shakespeare, when Caliban says, ‘You taught me language and my profit on’t it, I know how to curse’.

A central idea of Pinker’s book is what he calls ‘The Metaphor Metaphor’. Together with George Lakoff, Mark Johnson has been highly influential in developing a philosophy that takes metaphors of the body as both starting point and core concept. Johnson’s new book, The Meaning of the Body: Aesthetics of Human Understanding (University of Chicago Press, $54.95 hb, 326 pp), explores how meaning ‘grows out of our organic transactions with our environment’ to develop an ‘aesthetics of embodied meaning’. He draws on modern neuroscience to probe the ‘bodily roots of meaning’ and to argue that ‘meaning is not just a matter of concepts and propositions, but also reaches down into the images, sensorimotor schemas, feelings, qualities, and emotions that constitute our meaningful encounter with our world’.

Johnson’s book is in three parts. The first describes the origins of embodied meaning in movement, emotions and reasoning, taking clues from childhood development. The second reviews neural functions that ‘might plausibly underlie and make possible ... an alternative view of cognition and meaning – one that is embodied, nondualistic and naturalistic’. The final part turns to art for insight into the nature of meaning, expanding his view that ‘the arts are the primary means by which we grasp, criticize and transform meanings’.

Like Pinker, Johnson concludes that we can form concepts in the absence of explicit linguistic formulations. However, he takes this idea further, provocatively suggesting that ‘the very possibility of abstract conceptualization and reasoning depends on the fact that “body” and “mind” are not two separate things, but rather are abstractions from our ongoing, continuous, interactive experience’. Indeed, he considers thought to be an activity fundamentally similar to other brain-and-body functions such as seeing, hearing, walking or holding things. Many neuroscientists would agree.

Johnson argues that our widespread recognition of meaning in arts such as music or dance leads to clear rejection of the notion that only words can have meanings. While his discussion of meaning in visual art offers little new, his analysis of embodied meaning in music is interesting. He postulates that a shared embodiment of meaning underlies all forms of symbolic expression. Under these conditions, where ‘human beings are metaphorical creatures’, there can be no absolute truth. In contrast, ‘finite, fallible, human truth is all we have, and all we need’.

Central to the neuroscience that Johnson uses to ground his ideas are ‘mirror neurons’. These remarkable neural networks fire off when we observe a goal-directed action of another individual. In doing so, we effectively mirror the observed action in our own brain, almost as if we intend to carry out the same action ourselves. The final two books reviewed here describe the discovery of mirror neurons, and their implications for understanding human communication, both verbal and non-verbal.

In the early 1990s, Giacomo Rizzolatti and his colleagues at the University of Parma were studying neural activity in brain regions that plan hand movements. To their great surprise, some nerve cells that had been active when the subject picked up a small piece of food also were active when the subject saw an investigator pick up the morsel. These are the mirror neurons. In Mirrors of the Brain: How Our Minds Share Actions and Emotions (Giacomo Rizzolatti and Corrado Sinigaglia, OUP, $85 hb, 242 pp), Rizzolatti teams up with philosopher of science Corrado Sinigaglia to describe the development of these investigations and their relevance to human behaviour. The early chapters are quite technical as the authors introduce details of neuroanatomy necessary to understand their experiments. Although aimed at non-specialists, this material would be difficult for most readers without some background in neuroscience. However, perseverance is amply rewarded with a rare firsthand account of how subtle interactions between chance observation and brilliant experimental design led to a truly revolutionary discovery with impact far beyond the laboratory.

Marco Iacoboni is one of Rizzolatti’s long-standing collaborators. He heads a brain imaging laboratory at the University of California, Los Angeles, where he has studied mirror neurons in people examined under a wide range of conditions. Mirroring People: The New Science of How We Connect with Others (Marco Iacoboni, Farrar, Straus and Giroux, US$25 hb, 320 pp) describes the history of this innovative work and then carefully considers its potential impact on understanding human behaviour. This is outstanding popular science writing, again from an insider’s perspective, and deserves to be widely read. We witness a dramatic paradigm shift occurring not because of conflicting data or theories, as proposed by Thomas Kuhn in his The Structure of Scientific Revolutions (1970), but because of a unique combination of serendipitous observation, major technical advances and lateral thinking.

Iacoboni received international press coverage when a reporter leaked early results of his study into the neural bases of decision making by voters considering presidential candidates in the United States. Indeed, he argues convincingly that ‘we are at a point at which findings from neuroscience can significantly influence and change our society and our understanding of ourselves’. Does this presage a new era of corporate or political mind control wrapped in the guise of ‘scientific rigour’? Iacoboni is a humanitarian, well aware of this risk. Ultimately, he urges us to use this new know-ledge of how the brain works to inform public policy for the good, as ‘an invaluable resource for helping us determine how to reduce violent behaviour, increase empathy, and open ourselves to other cultures without forgetting our own’.

These are four stimulating, well-written books by authors at the peaks of their careers. Any one of them will challenge you to re-evaluate the way you think. Read them all, and it’s unlikely you will ever think the same way again about the world and your interactions with the people who inhabit it.