An algorithm isn't "just code"

I've been talking to many people about algorithmic fairness of late, and I've realized that at the core of pushback against algorithmic bias ("algorithms are just math! If the code is biased, just look at it and you can fix it !") is a deep misunderstanding of the nature of learning algorithms, and how they differ fundamentally from the traditional idea of an algorithm as "a finite set of well-defined elementary instructions that take an input and produce an output".

This misunderstanding is crucial, because it prevents people from realizing why algorithmic fairness is actually a real problem. And that prompted me to write a longer note that takes the "algorithm == recipe" analogy and turn it on its head to capture how machine learning algorithms work.