Hypothesis, experiment, observation, despair, coffee, conclusion. That is debugging, and apart from the coffee it is also science.
The discipline is in the isolation. One variable at a time, a way to reproduce, and a written record of what you already ruled out. Engineers who keep that record find bugs in minutes; engineers who do not find the same bug three times.
The despair step is real and worth naming. It usually arrives just before you question the assumption you never wrote down – the one that turns out to be wrong.
Print statements are a legitimate instrument. Anyone who tells you otherwise has not shipped anything under a deadline.