You're absolutely right. As a follow up I wrote https://commoncog.com/blog/the-mental-model-faq/ https://commoncog.com/blog/the-mental-model-faq/ where I finall

You're absolutely right. As a follow up I wrote https://commoncog.com/blog/the-mental-model-faq/ https://commoncog.com/blog/the-mental-model-faq/ where I finally figured out the three categories that Farnam Street was mixing up: The origins of mental models as a psychological construct may be traced back to Jean Piaget’s Theory of Cognitive Development. However, much of mental model writing today is not about Piaget’s original theory. It is instead used as a catch-all phrase to lump three different categories of ideas together: 1. Frameworks. A large portion of mental model writing is about frameworks for decision making and for life. Frameworks do not sound as sexy as ‘mental model’, so it benefits the writer to use the latter phrase, and not the former. An easy exercise for the reader: when reading a piece about mental models, substitute the word ‘mental model’ for ‘framework’. If this works, continue to substitute for the rest of the piece. You will notice that the word ‘framework’ comes with restrictive connotations that the term ‘mental model’ does not. For instance, writers will often claim that ‘mental models are the best way to make intelligent decisions’ — a claim they cannot make when talking about frameworks (nobody says ‘frameworks are the best way to make intelligent decisions!’). This is understandable: writers optimise for sounding insightful. 2. Thinking tools. A second, large portion of mental model writing is about thinking tools and techniques. Many of these techniques are drawn from the judgment and decision making literature, what I loosely call ‘rationality research’: a body of work that stretches from behavioural economics, philosophy, psychology, and finance. This category of mental model writing includes things like ‘reasoning from first principles’, and ‘cognitive bias avoidance’. The second part of my Putting Mental Models to Practice series concerns itself with this category of tools, and maps out the academic landscape that is of interest to the practitioner. 3. Mental representations. This is Piaget’s original theory, and it references the internal representations that we have of some problem domain. It is sometimes referred to as ‘tacit knowledge’, or ‘technê’ — as opposed to ‘explicit knowledge’ or ‘epistêmê’. Such mental representations are difficult to communicate through words, and must be learnt through practice and experience. They make up the basis of expertise (a claim that K. Anders Ericsson argues in his book about deliberate practice Peak).