So, in summary: "A hammer can be used for the following things: 1. To drive nails into another material 2. To 'hammer out' dents in sufficiently soft materia

So, in summary: "A hammer can be used for the following things: 1. To drive nails into another material 2. To 'hammer out' dents in sufficiently soft materials 3. As a weapon 4. As a doorstop 5. etc. Because some people only use it to do (1) and (3), it isn't a tool for (2)." P.S. I know the author acknowledges this in his own comment on the article.