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2 of 2 people found the following review helpful
4.0 out of 5 stars A comprehensive volume on logical thinking,
This review is from: How We Reason (Paperback)How We Reason by Philip Johnson-Laird, Oxford University Press, Oxford, 2006, 584 ff
A comprehensive volume on logical thinking
By Howard Jones
The size, publisher and subject matter of this book indicate that it is intended primarily for academic readership. However, the author's style is engaging and the text is accessible to any non-specialist interested in this topic. Philip Johnson-Laird is now a Professor of Psychology at Princeton University in New Jersey, having previously been on the staff at University College, London, and the Universities of Sussex and Cambridge, UK; he is the author of several books on this subject.
According to the author, we do not reason by logic or by using (if only subconsciously) the laws of probability but by considering all the possibilities of a situation and then determining what these possibilities have in common. The first parts of this book examine The World in Our Conscious Minds and The World in Our Unconscious Minds: of this part of the book the author argues `that we grasp the meanings of propositions and then use these meanings and our knowledge to construct mental models of the significance of the propositions', claiming that `all thought processes are unconscious, so these conscious deductions depend on unconscious processes.' The author then goes on to consider How we Make Deductions and How We Make Inductions: scientists and mathematicians will find this intriguing as it is about how we make connections between these propositions. The next Part explores What Makes Us Rational with an explanation of counter-examples and an investigation of the meaning of truth - the correspondence and the coherence theories of truth, and whether all propositions are necessarily either true or false.
The remaining parts of the book deal with How We Develop Our Ability to Reason; Knowledge, Beliefs and Problems; and finally Expert Reasoning in Technology, Logic and Science, with several chapters on various topics in each.
Overall then, the book deals with the laws of logical reasoning, including syllogisms, and discusses valid and spurious reasoning, from many different aspects; Sherlock Holmes and Hercule Poirot appear as examples of the logical mind and there's an easy Sudoku problem for readers to solve, which give the book a slightly less academic feel in places. The whole book is fascinating and entertaining, but you must want to explore the nature of logical thought - or perhaps have a penchant for logic puzzles - and really want to think about thinking! I suspect that the `general reader' may find it heavy going, but it is unquestionably a book of great and insightful scholarship. There is an extensive section of Notes, a list of References, a Name Index and a general Subject Index.
Dr Howard A. Jones is the author of The Thoughtful Guide to God (2006) and The Tao of Holism (2008), both published by O Books of Winchester, UK.
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1 of 1 people found the following review helpful
5.0 out of 5 stars A small but vital piece of the puzzle,
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This review is from: How We Reason (Paperback)Philip Johnson-Laird is a personal intellectual hero of mine since I discovered his wonderful little book The Computer and the Mind: An Introduction to Cognitive Science (Second Edition), which is a superb general introduction to the field of cognitive science. This book is rather more specialised, focussing on quite a specific area of the cognitive science domain, that of our reasoning faculties. The primary message of the book can be quite simply stated as being that we carry out reasoning tasks, of deduction and induction from premises, verifying them and so forth, by constructing mental models of the various possible states of affairs that a set of premises describes. We reason by paring down the list of such models as new premises are considered, until we are left with a single one, whereupon we have derived a new piece of knowledge from the given premises. The limitations of the cognitive architecture of the brain determine that we adopt strategies that minimise the number of models that must be held in mind simultaneously, in particular we have an in-built bias to construct models of what can be as opposed to what cannot. This latter feature Johnson Laird has coined the principle of truth. The consequent theory of mental models allows detailed predictions to be formulated about the limitations of human reason, and ways in which it can break down, all too often in ways unsuspected by the reasoner. These predictions have given rise to numerous, admirably cunning psychological experiments, which taken together make an impressive case for the mental model theory of Johnson Laird and his numerous co-workers. Alternative theories are considered. One such class of theories that has been popular, but is now losing ground, are those based on the various kinds of formal logic, propositional, modal, etc, that presume that we reason by breaking out the logical structure from information with which we are presented. Effectively differentiating the logical form from the contextual content. This approach proves to be unrealistic when actual real world knowledge so frequently has to constrain, or `modulate' the significance of the logical form of the premises with which we deal. Other notions that the mental models theory successfully combats are those that suggest that we have a variety of dedicated modules in the brain for dealing with different categories of reasoning. These might be say with regard to causation in the physics of movement and social, or deontic reasoning by which we analyse obligation and moral choice. Careful experimentation suggests that there is no evidence to support the idea that we reason differently, or more or less consistently or accurately in disparate domains.
This is a book that can be tackled by the layman. Though a large amount of the experimental evidence in these matters is statistical, the book presents the keys results as summarised from the statistics without bludgeoning you with the details. On the other hand this is a reasonably challenging book, demanding to be read with a great deal of care. In particular the nature of the material discussed obliges its illustration with frequent examples that take the form of logical puzzles, of varying degrees of difficulty, often couched to be deceptively so, one way or the other. It actually took me several weeks to read, over many short sittings. It might well be possible to read it just for the conclusions presented without directly engaging with the illustrative puzzles, but I would imagine that the force of the argument would be rather blunted if approached thus.
The book has little to say about memory, by which I mean how our knowledge of the world is represented in long term memory, and how it must be organised for our reasoning processes to be able to effectively activate and manipulate it. Presumably the processes of reasoning that Johnson Laird discusses are shifting patterns of activation within this substrate, and it is competition between these patterns that gives rise to our decisions and understanding about the world we inhabit. The means of organising the information that constitutes our massed knowledge of the world, for free and natural utilisation by processes of reasoning is, to my mind, the deepest mystery of cognitive science. This mystery is what stands between us and the creation of a revolutionary class of truly thinking machines, dreamed of for so long in science fiction, but still bafflingly remote. Alas, our current science lacks the theoretical models, and the practical imaging techniques to verify them, and is as yet incapable of shedding light on this much tougher part of the puzzle. But it is to be hoped that by clarifying what can be understood about our reasoning we might perhaps garner the insights by which we might begin to infer this hidden structure of our knowledge of the world. As such this book takes us on a stimulating journey into new areas of our understanding, but also casts into relief adjacent areas of ignorance.
5.0 out of 5 stars Model Behavior,
This review is from: How We Reason (Paperback)Philip Johnson-Laird's most recent book is about how we reason, as we might infer from its title. It continues the discussion of mental models begun in his 1986 book titled--wait for it--Mental Models. The author describes the mental mechanisms used to reason at a level of detail useful to researchers in this area. Those interested in a discussion of the steps and strategies of reasoning as non-specialists see it might be better served by Frank Yates' Judgment and Decision Making or Decision Management: How to Assure Better Decisions in Your Company.
This book dives into the details. Previous approaches have defined reason as "[a] set of processes that construct and evaluate implications among sets of propositions." Contrary to our expectations, the author argues, formal logic cannot be the basis for human reason. Johnson-Laird reviews evidence to this effect. For example, there are many valid conclusions that we never bother to draw because they are of no practical use to us. We also make systematic errors in reasoning that we would not make using logic. The content of logic problems used in research studies greatly affects their difficulty; it would not if logic were the primary process. We use knowledge to help us imagine possibilities and then evaluate the possibilities for consistency with other evidence.
Constrained by the span of short term memory, the strength of our general intellectual abilities, and our level of expertise, we construct and manipulate mental models of the problems we reason about. "...[F]rom the meanings of sentences in connected discourse, the listener implicitly sets up a much abbreviated and not especially linguistic model of the narrative ... Where the model is incomplete, material may even be unwittingly invented to render the memory more meaningful or more plausible." We can manipulate these models in a number of ways, including updating them with new information, combining two models when appropriate, searching for confirming evidence or information, and using counterexamples to challenge a model's validity.
Mental model theory explains a number of systematic errors human beings make when reasoning. For example, the difficulty of reasoning problems is related to the number of models that must be held simultaneously in memory to work through them. And we exhibit a recurring bias to use a single model to reason about situations that have more possibilities than we can keep track of. We oversimplify. Consistent with model theory, we have difficulty reasoning with information about what is false about a situation. Our models can be both informed and misled by our knowledge and experience.
The real key to human rationality is our ability to recognize and grasp the implications of counterexamples. Johnson-Laird redefines reason as "...the ability to construct models from perception, description, and knowledge, to formulate novel but parsimonious conclusions from these models, and to grasp the force of counterexamples to these conclusions." He explores the implications of the model account of reasoning for the childhood development of mental abilities, strategies for improving reasoning, and the development and deployment of expertise.
The author closes with a trio of insightful chapters that employ model theory to understand reasoning by experts in diverse fields. Case studies include the Wright brothers' innovations in powered flight, efforts by cryptographers to reverse-engineer the Enigma code machine during WWII, and early epidemiological studies of infection patterns during a nineteenth-century cholera epidemic.
This book is recommended to psychologists and their students studying human reason. It is also accessible by and beneficial to those without backgrounds in psychology. Johnson-Laird's arguments are plain and his examples are clear. He is an expert in the study of reason and presents his conclusions about its nature formed during decades of careful research.
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How We Reason by Philip Johnson-Laird (Paperback - 23 Oct 2008)