This post prompted me to survey the “Sent” folder of my email archives looking at how I use the phrase “by definition”. I plead guilty to a few illegitimate uses of the sort covered in the post.
There is also at least one type of legitimate usage “outside of math”, which I resort to fairly often. It consists of reminding my interlocutors of some consequences of the definition of a term that we have previously agreed on as a shorthand for some complex intension.
Interestingly, some of the oldest examples are from when I was playing the game of Nomic over email—the game consists of making changes to its own rules, usually by voting on change proposals, and a common type of move consists of making up a definition of this type within a rule, e.g. “A player’s Loudness shall be defined as the number of emails they sent to the list in the past seven days.” The legal effects of a definition contained in a rule are derived from its literal wording, as opposed to its intended meaning, so you can use “by definition” to straigthen out someone who is appealing to an intuitive, but wrong, understanding of a term so defined.
Other examples revolve around “terms of art”, a word that has a special meaning in a given context. In Agile software development, the term “velocity” has a technical definition, which is “the sum of the estimates originally assigned to all features which were fully implemented in the previous iteration”. Novices sometimes overload that with other meanings, such as “how much work to plan for the next iteration”, so they’ll ask questions like “one of my developers is going to take a vacation next month, how much should I lower velocity” ? Then I might remind them that by definition velocity is something observed, not decided upon.
This post prompted me to survey the “Sent” folder of my email archives looking at how I use the phrase “by definition”. I plead guilty to a few illegitimate uses of the sort covered in the post.
There is also at least one type of legitimate usage “outside of math”, which I resort to fairly often. It consists of reminding my interlocutors of some consequences of the definition of a term that we have previously agreed on as a shorthand for some complex intension.
Interestingly, some of the oldest examples are from when I was playing the game of Nomic over email—the game consists of making changes to its own rules, usually by voting on change proposals, and a common type of move consists of making up a definition of this type within a rule, e.g. “A player’s Loudness shall be defined as the number of emails they sent to the list in the past seven days.” The legal effects of a definition contained in a rule are derived from its literal wording, as opposed to its intended meaning, so you can use “by definition” to straigthen out someone who is appealing to an intuitive, but wrong, understanding of a term so defined.
Other examples revolve around “terms of art”, a word that has a special meaning in a given context. In Agile software development, the term “velocity” has a technical definition, which is “the sum of the estimates originally assigned to all features which were fully implemented in the previous iteration”. Novices sometimes overload that with other meanings, such as “how much work to plan for the next iteration”, so they’ll ask questions like “one of my developers is going to take a vacation next month, how much should I lower velocity” ? Then I might remind them that by definition velocity is something observed, not decided upon.