The renowned psychologist and cognition guru, Philip Johnson-Laird discusses the three different forms of reasoning and the single biggest error in human thinking
You have called reasoning “the core of human thinking”. How do you define it?
Which is the most valuable form of reasoning in today’s environment?
In one 18-month study, this simple list is estimated to have saved the lives of over 1,500 patients. A former PhD student of mine, Victoria Bell has extended the checklist idea to improve reasoning. She teaches people in about two minutes what she calls ‘the model method’. Here’s a simplified example to illustrate: suppose you know that a fault has occurred either in your computer or in your printer. Draw a line down the middle of a piece of paper and put ‘computer’ at the head of one column and ‘printer’ at the head of the other. Then, as you receive further information, add it to the relevant column or columns. Say you discover that the ink cartridge can run out without warning; you would add that under the ‘Printer’ column. You keep updating the possibilities as each piece of information comes in; and some information may enable you to delete an entire column, because it is no longer a viable possibility.
[This article has been reprinted, with permission, from Rotman Management, the magazine of the University of Toronto's Rotman School of Management]