Should we use don't or doesn't in the below sentence and why?
"Knowing magic secrets doesn’t make you a magician"
"Don't/doesn't" work in the absolutely same way as "do/does".
If there is one countable unit (or a gerund) or one uncountable unit then "doesn't", if there are more than one unit or a plural amount then "don't":
However, in cases when we render several units as a single unit, or as something abstract we use "doesn't":