There’s already evidence for it. There are contemporary accounts describing the practice.

These accounts aren’t perfect. Not necessarily first hand eye witnesses, but not rumor mongers either.

So anyone arguing that this didn’t happen needs to address an established consensus.

Lots of more recent research is attacking traditional ideas about the Spartans, so this is a welcome argument.

But saying “it’s on them to prove their point” isn’t really helpful.

The onus is on the people making claims in general. In this case someone (the journalist?) made a claim that "spartans didn't kill `weak' babies", so the onus is on them.

No, if the evidence for the area points to X, the folks claiming a deviation from the general evidenced trend need to provide evidence for that.

This paper isn’t making an argument. It’s summarizing specialized research.

A specialist in the area could just say “appeal to authority” and they’d be right. The actual peer reviewed articles and books would require evidence.

But those articles and books wouldn’t be accessible to the average reader.

So the journalist is summarizing those arguments, but in the process reducing them to an appeal to authority - which is completely fine.

We don’t really know anything about Sparta which wasn’t written by outside observers.

Where did the claim come from originally ? Could google but...

Either way, Sparta is not Athens. They were different political and cultural systems.

The "concept of 'onus'" applies to the writer or whoever is making a claim, not to the reader.

The preceding post did not claim otherwise.