In essence, this is the place for Discussion and Debate.
In general, anything which has multiple viewpoints is suitable. So, the range of possible topics is quite diverse, from Is Mathematics A Language? to This Thread Does Not Exist!.
Threads here do NOT necessarily have to be serious! So long as you can discuss/debate a topic based on evidence (factual or facetious as the case may be), it's allowed.
The Nature of Discussion ...