As much as we shampoo it, style it, cut it, and fret over it, hair continues to be a mystery to us. We speculate on its nature, especially its propensity for sprouting in our middle years in places we didn’t want it to, even as it disappears from locations where we would much rather it had stayed put. We wonder if it continues to grow after we die. (It doesn’t.) And we worry that shaving or cutting it will make hair grow back thicker or darker or coarser.

Shavers and clippers take heart: in your quest for tonsorial perfection, you are not creating a larger problem for yourself through your efforts. Cutting does not stimulate new growth. (If it did, those going bald would be shaving afflicted areas to encourage regrowth of what they’re losing.) This belief probably stems from the perception that short hair seems to be tougher than longer hair. Hair expert Philip Kingsley recommends thinking of a bamboo cane: a long cane flexes easily, but the same cane cut short feels harder and tougher. Another reason for the belief resides with the naturally finer ends of uncut hair: compare the end of a long-lived hair with that of a hair recently cut or shaved, and you’ll see the one is thicker than the other. That could lead the less-than-careful to conclude that the whole of the hair’s shaft became thicker as a result of the hair’s being cut (which it didn’t) rather than to realize that shaving or cutting results in a blunt termination, whereas natural outgrowth concludes in a tapering.

The part of the hair we style is already dead. The living sections lie below the surface of the scalp. Cutting or shaving the extreme end of the dead section isn’t going to have an impact on the parts that are alive. Go forth to shave and trim as much as you like — you will not be affecting the intrinsic nature of your hair.

Other mistaken hair beliefs include: