Johnson-Laird – How we Reason

Posted on August 6, 2008


Just in the last few days I have finished reading Philip Johnson-Laird’s How we Reason. It is something of a monster of a book, both in terms of size and in terms of depth. He has put together the results of the research he has carried out over his whole career into a single picture that is both coherent and comprehensive. The basic idea that drives the book is his mental model theory, i.e. that people reason using mental models that are largely iconic representations of the world. While that’s a simple enough concept, Johnson-Laird makes it do a hell of a lot of work. For example, he explains the implications this has for the human ability to evaluate deductive arguments. Without going into the details, the picture Johnson-Laird draws is one that I find myself very much drawn to and I think that his approach offers a way to think about deductive reasoning in the context of bounded rationality, something that I’d been having some serious worries about. Mind you, to properly understand everything that Johnson-Laird writes I would probably have to read the book several more times. He tries to make it as easy to understand as possible but, still, it is somewhat overwhelming to be confronted with it all. Kind of like being shown every single cog in a massive clockwork machine. I just hope that I have understood enough that the review I wrote of it doesn’t contain any egregious errors.