Sharp membership boundaries, however, often result in people forgetting the fuzziness of the concept - there are some people who vote without being responsible adults, because they can; an essay can be boring and rambling at 450 words or impressive and concise at 600; and food can be good a bit past its expiration date (it doesn't usually go in the other direction in my experience, presumably because the risk of eating spoiled food vastly outweighs the risk of mistakenly tossing out good food, so expiration dates are the very early estimates).