If none of those terms makes any sense to you, here's a quick run-down:
Logos is an argument from logic: it's the assertion that the pool is contaminated because there are five confirmed elevated concentrations of strychnine and seven mosquito nests.
Ethos is an argument from expertise (usually moral): it's saying that the pool is contaminated because I'm an expert on water quality and I should know.
Pathos is an argument from emotion: it says the pool is contaminated because of those kids that got sick and had to go to hospital for a few weeks.
Bathos is what happens when you screw up pathos: it's the argument that apparently more kids got sick and/or died from swimming in that one pool than live in the county.
I'm not certain why, but my dividing line between pathos and bathos is really really thin and really easy to cross; see "From the Annals of TV Tropes" for an example (archives on right). And for some reason, pathos is on full display in every area of politics, no more so than in places like Health Care, Global Warming....
This isn't to say it's a completely torrid affair--the Congressional Budget Office has kept its head, and most of the commentors on National Review (especially Krauthammer and Hanson; Steyn is deliberately going for bathos for comic effect) are very calm. But to listen to those people the media love to show in town hall clips, advocacy groups on every side of the line, and the President's media offices is like a big heaping combo dose of laughing gas and ipecac (a vomit inducer).
People, I'm a logos man! Most people, I suspect, are logos men! Argue to my brain, not my heart, and you have a much better chance of getting me to listen to you and not pick you apart.