# What is the truth about having at least one hair on someone's head means they have a full head of ha **URL:** \ **Category:** Factual Questions\ **Created:** [February 15, 2019, 11:59pm UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643 "2019-02-15T23:59:28Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Dunmurry](https://avatars.discourse-cdn.com/v4/letter/d/d2c977/32.png) [@Dunmurry](https://boards.straightdope.com/u/Dunmurry)\ **Post date:** [February 15, 2019, 11:59pm UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/1 "2019-02-15T23:59:28Z")
I believe that mathematically speaking one hair can’t make the difference between being bald and not being bald. So is it the case that if someone has at least one hair on their head mathematically speaking they have a full head of hair ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [February 16, 2019, 12:27am UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/2 "2019-02-16T00:27:37Z")
Only if you define bald to mean “zero hairs.” But in common parlance, that’s not what bald means. Most bald people are not completely domed in chrome. This is actually one of Zeno’s famous paradoxes. (Not the one he is most famous for about halving distances; he actually wrote about several.) > [@Zeno](#): > > A single grain of rice does not make a sound when it is dropped, but a thousand grains of rice make a sound when dropped. Therefore nothing = something. Of course, Zeno is wrong in both his premise and conclusion. A single grain of rice _does_ make a sound when it falls, it’s just not very loud. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [February 16, 2019, 12:29am UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/3 "2019-02-16T00:29:17Z")
To see this is false, it suffices to exhibit someone with at least one hair but without a full head of 100000 hairs. Cf pattern hair loss. ---
**Author:** ![Baron\_Greenback](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/baron_greenback/32/48_2.png) [@Baron\_Greenback](https://boards.straightdope.com/u/Baron_Greenback)\ **Post date:** [February 16, 2019, 12:30am UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/4 "2019-02-16T00:30:13Z")
I feel the length of the single hair, and the skill of the hair stylist, are significant factors here. Admittedly that’s more from an aesthetic perspective than a strictly mathematical one. :dubious: ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [February 16, 2019, 12:53am UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/5 "2019-02-16T00:53:10Z")
> [@friedo](#): > > Only if you define bald to mean “zero hairs.” And only if you define “full head of hair” as one hair. This is why math is not defined by words. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [February 16, 2019, 1:21am UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/6 "2019-02-16T01:21:23Z")
It only matters what a prospective partner thinks. This is where the literal meets the practical. ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [February 16, 2019, 1:26am UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/7 "2019-02-16T01:26:33Z")
I believe there is a difference between “not being bald” and “having a full head of hair.” Cite: my head. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 16, 2019, 2:51am UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/8 "2019-02-16T02:51:21Z")
If a full head of hair is 100,000 hairs, then a single hair is not a “full head of hair”. It is a head that is 0.001% full. A head with two hairs would then be 0.002% full, and so on. ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [February 16, 2019, 3:53am UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/9 "2019-02-16T03:53:24Z")
[It’s the sorites paradox](https://plato.stanford.edu/entries/sorites-paradox/): > [@](#): > > The sorites paradox originated in an ancient puzzle that appears to be generated by vague terms, viz., terms with unclear (“blurred” or “fuzzy”) boundaries of application. ‘Bald’, ‘heap’, ‘tall’, ‘old’, and ‘blue’ are prime examples of vague terms: no clear line divides people who are bald from people who are not, or blue objects from green (hence not blue), or old people from middle-aged (hence not old). Because the predicate ‘heap’ has unclear boundaries, it seems that no single grain of wheat can make the difference between a number of grains that does, and a number that does not, make a heap. Therefore, since one grain of wheat does not make a heap, it follows that two grains do not; and if two do not, then three do not; and so on. This reasoning leads to the absurd conclusion that no number of grains of wheat make a heap. > > [snip] > > The Megarian philosopher Eubulides (4[sup]th[/sup] century BC) is usually credited with the first formulation of the puzzle. (The name ‘sorites’ derives from the Greek word _soros_, meaning ‘heap’.) Although we don’t know his motivations for introducing it (along with several other legendary puzzles), the paradox was later used by Greek philosophers as a dialectical weapon, most notably by the Sceptics against the Stoics’ claims to knowledge. > > Curiously, the paradox attracted little subsequent interest until the late 19[sup]th[/sup] century. Marxist philosophers in the neo-Hegelian tradition, like Plekhanov (1908 [1937: 114]), cited the paradox as evidence of the failure of “customary” logic and the utility of the ‘logic of contradiction’. In this way some Marxists sought to establish the triumph of the dialectic. Meanwhile, in Anglo-American philosophy, formal logic regained its central place, and its classical formalisation left no room for the vagueness of natural language. Vagueness and the associated paradox were seen as lying beyond the scope of logic and so posing no challenge to it. However, since the demise of the ideal language doctrines of the latter half of the twentieth century (see §3.1), interest in the idiosyncrasies of natural language, including its vagueness, has greatly increased. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [February 16, 2019, 11:56am UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/10 "2019-02-16T11:56:00Z")
> [@Chronos](#): > > If a full head of hair is 100,000 hairs, then a single hair is not a “full head of hair”. It is a head that is 0.001% full. A head with two hairs would then be 0.002% full, and so on. Pursuing and generalizing this idea, “bald” and “with a full head of hair” may be regarded as predicates in formal [fuzzy logic](https://en.wikipedia.org/wiki/Fuzzy_logic). A piecewise-linear function is a simple and straightforward way to delineate the fuzzy sets involved. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [February 16, 2019, 1:58pm UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/11 "2019-02-16T13:58:18Z")
This is just one example of many of people who want nice sharp boundaries in definitions when the real world quite often doesn’t work that way. Whether being fuzzy headed is bald or not is … fuzzy. Get used to it. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [February 16, 2019, 2:18pm UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/12 "2019-02-16T14:18:29Z")
> [@Baron\_Greenback](#): > > I feel the length of the single hair, and the skill of the hair stylist, are significant factors here. Admittedly that’s more from an aesthetic perspective than a strictly mathematical one. > > :dubious: I’m picturing the most extreme comb-over ever. ---
**Author:** ![Frodo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/frodo/32/302_2.png) [@Frodo](https://boards.straightdope.com/u/Frodo)\ **Post date:** [February 16, 2019, 7:03pm UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/13 "2019-02-16T19:03:03Z")
> [@kayaker](#): > > I’m picturing the most extreme comb-over ever. One of truly Trumpian proportions! ---
**Author:** ![Jackmannii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jackmannii/32/311_2.png) [@Jackmannii](https://boards.straightdope.com/u/Jackmannii)\ **Post date:** [February 16, 2019, 10:27pm UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/14 "2019-02-16T22:27:20Z")
> [@Dunmurry](#): > > So is it the case that if someone has at least one hair on their head mathematically speaking they have a full head of hair I don’t know about the math, but it’s the best news I’ve had this week.🙂 ---
**Author:** ![Baron\_Greenback](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/baron_greenback/32/48_2.png) [@Baron\_Greenback](https://boards.straightdope.com/u/Baron_Greenback)\ **Post date:** [February 16, 2019, 10:29pm UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/15 "2019-02-16T22:29:56Z")
> [@kayaker](#): > > I’m picturing the most extreme comb-over ever. I’m picturing a really big coil placed atop the bonce. ---
**Author:** ![Lulu8360](https://avatars.discourse-cdn.com/v4/letter/l/3d9bf3/32.png) [@Lulu8360](https://boards.straightdope.com/u/Lulu8360)\ **Post date:** [February 22, 2019, 9:47am UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/16 "2019-02-22T09:47:25Z")
The Oxford English Dictionary defines bald as “Having a scalp wholly or partly lacking hair.” So there are many ways to be bald. Then there are bald eagles, which have never had even one hair on their heads. ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [February 22, 2019, 11:04am UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/17 "2019-02-22T11:04:55Z")
> [@ftg](#): > > This is just one example of many of people who want nice sharp boundaries in definitions when the real world quite often doesn’t work that way. > > Whether being fuzzy headed is bald or not is … fuzzy. Get used to it. Yes and indeed ISTM that fuzzy logic basically solves this class of problems. It’s weird how often the paradox still gets brought up. Every hair that is removed indeed makes some difference: it increases a “baldness” attribute and decreases a “haired” attribute. If a person has less than, say 2000 hairs everyone would regard him as bald, and above, i dunno, 10,000 every human would say he has a head full of hair. But inbetween these thresholds our brains only need to do something like a collapse of a fuzzy function to take the values of the two attributes and make some decision. (Also if we allow the state “balding” then that too can have fuzzy divisions with “bald” and “full head of hair”) ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [February 22, 2019, 11:51am UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/18 "2019-02-22T11:51:17Z")
When I was bald-by-choice for a few years I had to shave morning _and_ evening, otherwise I had a full head of (very short) hair. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 22, 2019, 12:08pm UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/19 "2019-02-22T12:08:55Z")
> [@](#): > > Quoth **Lulu8360** : > > Then there are bald eagles, which have never had even one hair on their heads. I dunno; sometimes when you snag a rabbit, it’s shedding season. ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [February 23, 2019, 3:07pm UTC](https://boards.straightdope.com/t/what-is-the-truth-about-having-at-least-one-hair-on-someones-head-means-they-have-a-full-head-of-ha/829643/20 "2019-02-23T15:07:09Z")
> [@Dunmurry](#): > > I believe that mathematically speaking one hair can’t make the difference between being bald and not being bald. So is it the case that if someone has at least one hair on their head mathematically speaking they have a full head of hair How does this question even arise? What does it mean “mathematically speaking” and “one hair can’t make the difference between being bald and not being bald”? Others have mentioned sorites paradox and how mathematics approaches questions of this nature. > [@DPRK](#): > > Pursuing and generalizing this idea, “bald” and “with a full head of hair” may be regarded as predicates in formal [fuzzy logic](https://en.wikipedia.org/wiki/Fuzzy_logic). A piecewise-linear function is a simple and straightforward way to delineate the fuzzy sets involved. He said “fuzzy logic”. [snerk] (I know what fuzzy logic is. I R A Engine-er. Just “fuzzy” with respect to hair is funny.)