And by listing negative effects, you can also make bad things sound bad.
Lots of people kill themselves with marathons. Maybe there's a right way to do it, but obviously it's easy to do it the wrong way. Which makes marathons dangerous until someone figures out your right way.
"if running a marathon is bad, then surely running half a marathon is still not good, right?"
No. Does not follow. As you say, there are probably distances where the good far outweighs the bad. 26 miles is not that distance.
Lots of people kill themselves with marathons. Maybe there's a right way to do it, but obviously it's easy to do it the wrong way. Which makes marathons dangerous until someone figures out your right way.
"if running a marathon is bad, then surely running half a marathon is still not good, right?"
No. Does not follow. As you say, there are probably distances where the good far outweighs the bad. 26 miles is not that distance.