Call me shallow, but I love it when philosophers take up seemingly trivial things like beards. Perhaps it is because I love to make mountains out of molehills (find the profound and deep in the simple and the ordinary). After all, some of the most elevating philosophical discussions I have had started with arguments about sports.
Anyway, I stumbled on this passage from the Discourses on Epictetus (a stoic) by Roman historian Lucius Flavius Arrian (86-160AD). It takes up the question of facial hair from the stoic point of view (generally, that peace will be found when you align your will with what nature accords).
Well, let us omit the works of nature and contemplate her smaller acts. Is there anything less useful than the hair on the chin? What then, has not nature used this hair also in the most suitable manner possible? Has she not by it distinguished the male and the female? does not the nature of every man forthwith proclaim from a distance, "I am a man; as such approach me, as such speak to me; look for nothing else; see the signs"? Again, in the case of women, as she has mingled something softer in the voice, so she has also deprived them of hair (on the chin). You say: "Not so; the human animal ought to have been left without marks of distinction, and each of us should have been obliged to proclaim, ‘I am a man.’ But how is not the sign beautiful and becoming, and venerable? how much more beautiful than the cock’s comb, how much more becoming than the lion’s mane? For this reason we ought to preserve the signs which God has given, we ought not to throw them away, nor to confound, as much as we can, the distinctions of the sexes.
Young man, whom do you wish to make beautiful? In the first place, know who you are and then adorn yourself appropriately. You are a human being; and this is a mortal animal which has the power of using appearances rationally. But what is meant by "rationally?" Conformably to nature and completely. What, then, do you possess which is peculiar? Is it the animal part? No. Is it the condition of mortality? No. Is it the power of using appearances? No. You possess the rational faculty as a peculiar thing: adorn and beautify this; but leave your hair to him who made it as he chose. Come, what other appellations have you? Are you man or woman? "Man." Adorn yourself then as man, not as woman. Woman is naturally smooth and delicate; and if she has much hair (on her body), she is a monster and is exhibited at Rome among monsters. And in a man it is monstrous not to have hair; and if he has no hair, he is a monster; but if he cuts off his hairs and plucks them out, what shall we do with him? where shall we exhibit him? and under what name shall we show him? "I will exhibit to you a man who chooses to be a woman rather than a man." What a terrible sight! There is no man who will not wonder at such a notice. Indeed I think that the men who pluck out their hairs do what they do without knowing what they do. Man what fault have you to find with your nature? That it made you a man? What then? was it fit that nature should make all human creatures women? and what advantage in that case would you have had in being adorned? for whom would you have adorned yourself, if all human creatures were women? But you are not pleased with the matter: set to work then upon the whole business. Take away- what is its name?- that which is the cause of the hairs: make yourself a woman in all respects, that we may not be mistaken: do not make one half man, and the other half woman. Whom do you wish to please? The women?, Please them as a man. "Well; but they like smooth men." Will you not hang yourself? and if women took delight in catamites, would you become one? Is this your business? were you born for this purpose, that dissolute women should delight in you? Shall we make such a one as you a citizen of Corinth and perchance a prefect of the city, or chief of the youth, or general or superintendent of the games? Well, and when you have taken a wife, do you intend to have your hairs plucked out? To please whom and for what purpose? And when you have begotten children, will you introduce them also into the state with the habit of plucking their hairs? A beautiful citizen, and senator and rhetorician. We ought to pray that such young men be born among us and brought up.
Do not so, I entreat you by the Gods, young man: but when you have once heard these words, go away and say to yourself, "Epictetus has not said this to me; for how could he? but some propitious good through him: for it would never have come into his thoughts to say this, since he is not accustomed to talk thus with any person. Come then let us obey God, that we may not be subject to his anger."