Where do you want to go from here?

The following use case was a great discussion with friends, which gave no simple answer. That's the reason I decided to publish it online.

When you're reading an article and you see links for Previous and Next posts, where should they take you - to the previous or next post in the category, the current article is, or to the previous/next post based on the overall blog activity?

What do you think? Where do you want to go from these <Prev and Next> links?