Are multiple intelligences real? No.
There are eight or nine separate intelligences — musical, bodily, interpersonal — and teaching should address each one.
Gardner proposed the framework in 1983 from a reading of the literature rather than from data, and never produced a test for it. The abilities it separates correlate with one another, which is the pattern a general factor produces. Waterhouse’s reviews from 2006 onward found no empirical studies supporting the model, and Gardner himself has objected to it being turned into a set of measurable ability factors or conflated with learning styles.
Check it yourself: doi.org/10.1207/s15326985ep4104_1
Real differences between learners live in prior knowledge, interest and practice history. Teach to what someone already knows and give feedback at the edge of what they can currently do.
Every law on Useful Mind tells you how strong the evidence behind it is. The ones that failed are kept here rather than quietly deleted, because knowing which advice is wrong saves you as much as knowing which is right.
See the ones that held up