Final answer:
A user without a role can read articles but cannot contribute to a knowledge base if no user criteria are selected.
Step-by-step explanation:
If a knowledge base and its articles have no user criteria selected, a user without a role can read articles, but not contribute. This is typically how most knowledge bases are set up to ensure that content remains accurate and is only changed by those with the proper authority or knowledge to do so. On the other hand, access to read is generally considered safe to be public or available to all users within an organization or community, as it does not risk the integrity of the information presented in the knowledge base.