There are many expressions of categorism. Young identifies five of them in her essay Five Faces of Oppression, but there are also many others. How do we know whether something is a expression of categorism or not?
The answer is that we must look to the three Archetypical facets of categorism: Prejudice, bigotry and discrimination. Together, these three and categorism helps defining each other: Prejudice equals categorist beliefs, bigotry equals categorist feelings, and discrimination equals categorist acts. For something to fully be a specific expression of categorism, it must be based on of at least one of these three archetypical expressions.
Within reason, we should always keep an open mind and an open heart while treating each other well. To dismiss an idea, to despise a person or to treat someone in a hurtful manner may be justified, but the burden of proof is always on those who claim that it is so. The stronger the claim, the stronger the need for evidence. There should always be room for a reasonable level of preconceptions, acceptance of negative feelings and a freedom of choice.
Besides being based on prejudice, bigotry or discrimination, an expression of categorism can also be reinforcing, protecting or leading to at least one of the three. When something isn't based on any of the three but still reinforce, protect or lead to at least one of the three, then it is linked to categorism without fully being an expression of it.
For example, the phenomena of “stigmatization” is often based on prejudice, bigotry or discrimination. Or all three of them at once. Yet, some cases of stigmatitzation are not cases of these archetype expressions, and thus not cases of categorism. For example, to stigmatize a person for having murdered a fellow human being may be a case of justified disdain rather than a case of bigotry. As well as a case of reasonably negative special treatment rather than a case of discrimination. Yet this justified stigmatization of an actual murderer may spill over into prejudiced certainty that this person who has actually committed exactly one murder would secretly be guilty of hundreds of other murders as well.