Stereotypes come from commonalities amongst a group of people. They are real and they are legitimate. The key is to not base decisions or actions toward an individual based on a caricature of the whole.
It also depends on the nature of the stereotype as not all stereotypes are even based on hard facts or statistics of a majority but also from a biased cultural perception of a group.
You may want to consider what the original source of the concept is. The term "stereotype" originated in theatre. You may read a novel, most all of the details are there, word for word. You see that novel in a play, much has to be said with minute nuances, particularly in the characters' appearances, especially their dress, countenance and mannerisms. "Stereo" has to do with "depth" perception, the amalgamation of myriad nuances into a character's presence on the stage contributes volumes to giving the audience members depth into the character. We have "stereovision" and "stereoaudience" by having two eyes and two ears, giving us distance perception gravity through triangulation. Triangles demonstrate discriminating faculties and are used in Tantra as virtual realities furthering both mind expansion and discriminating capabilities. In the contemporary use, outside of theatre, for the term "stereotype/stereotyping", we endeavor to "grok" where someone is coming from. Much shallower than this is "inflicting" preconceived notions upon other people, determined by facts or beliefs about a prescribed demographic, usually. I can assure that dogs bark and cats meow, though on rare ocassions you can or will hear a cat bark too, naturally. You may also want to look up other terms in contemporary use, which may not actually mean what you think they do: sophisticated [see also sophistry]; fundamental[ism]. What matters is using the information morally. While demographics may have tendencies of behavior, our intercourse with people of that demographic must also draw the acceptance of them subconsciously, including into the fold of magnanimous and universal standards of behavior beneficial to all. For example, spend the next month or two, when you are in public, watching who washes their hands after using public restrooms. Even do something to increase your numbers of visits to public restrooms so that you can further add to what you witness for yourself. Especially when people crap in der comode, it is rather imperative to wash one's hands promptly afterwards, correct? Even when the availability of toilet paper, and water, is rather abundant in modern times. I have total confidence you'll witness a demographic specificity constituted by those who do not and will not wash their hands, even when encouraged. For this experiment, simply watch, make notes and consequently guffaw how such demographics are consistent, then revue whether you'd ever want to shake hands with another within that demographic, ever again. The moral depravity is not and will not be with you for what you've witnessed for yourself, the moral depravity will be with the people you'll witness who will not only NOT wash their hands after crapping, they will also be hostile and contentious, and virulently purposefully anti-social and hateful, with intent, with non-handwashing as an instrument of violence against those they despise. Witness for yourself, be honest, be truthful, and prepare for amending your participation with such people.
^most people assume that all stereotypes are a generalization based on a truth but that is not the case. there are different types of stereotypes and the ones that are correct, are the ones based on facts. the ones that aren't are the ones that are just based on cultural mores or "lens" that is projected onto another. they tend to scapegoat one group or pigeonhole when in reality may be a characteristic of other groups which is misleading. the problem is that people tend to assume all stereotypes are based on some truth and that is false. some are and some are based purely on emotional or biased perception.
Usually there's no smoke without fire, but remember there are always exceptions, and there is always the possibility of a situation where whoever shouts loudest dictates the "truth".
I don't think every black man is a white child abductor. Its just that I know white people with black children, but I don't know any black people with white children.
Quite a few people and enterprises are so gratuitously self-congratulatingly condescending that they do not, will not acknowledge that their condescentions have nothing to do with being magnanimous, liberal or progressive; condescention is masturbatory vanity surfing and necessitates a presumption of grandeur from which such condescentions are pretensed. In the County of Los Angels, for example, the nearly all black operatorss of the of the core office and every branch office of child welfare almost never ever let "white" people adopt black children, despite black children being the majority of children in need of adoption and there being a vast number of morally mature, financially capable, socially progressive, and magnanimous white couples prepared and willing to adopt them.
Stereotypes are a form of truism, and all truisms are true. The only kicker is that the truths they contain are not necessarily the ones they attempt to assert. The unjustified part is in the application of a stereotype to an individual.
Our brain operates on the basis of stereotypes. That doesn't justify them, they do make the stereotype a reality of human interaction, interpretation and action.
Best answer thus far. Stereotyping is natural human behaviour. It doesn't justify bigotry, racism, or self-righteousness but it does sometimes serve to protect us and keep us from harm. It's an instinct we are told we must surpress, but I think that it does have it's time and place. There is an interesting article here; http://www.scientificamerican.com/article.cfm?id=racial-stereotypes-children It's about how there is a specific syndrome that can cause people not to have discernable prejudice if they do not have outside social influences, but it's a neurological impairment. Too early to difinitively say whether it's genetic or not, but there is definitely something in our brain that makes us choose. It's unchecked prejudice that is based on fear that is the real problem in society, not stereotyping itself. That said, beware of the people who use words like "all" when describing a certain group or type of person. They have already made up their mind and you can't change it. In this world, there will always be deviations. But telling us to ignore instinct may not be the best approach either because it can lead to apathy and a lack of compassion.
It's not racist. There's a difference between stereotypes and playing the averages. Saying, "That guy is black, so he must be a criminal." is a stereotype and racist. Saying, "That guy is black, so he's statistically more likely to have a criminal record than the white guy." isn't racist or a stereotype.
