Shin and Mill (2021) propose four steps children go through when learning "variable form use." Although I applaud Shin and Miller's focus on morphosyntactic variation, their accrual of evidence is post hoc and selective. Fortunately, Shin and Miller recognize this and encourage tests of their ideas. In support of their work, I share data…

When acquiring the English plural, children correctly produce plural words long before they develop an understanding of morphological structure. When acquiring Sesotho noun prefixes, children are aware of the multiple constraints governing variation from a young age. Both of these cases raise questions about the Shin and Miller (2022) account of…