first rule in economics: people think rationally?

ok there is something i just dont understand about the hostility towards advertising ... in my advertising ethics class the other day we were talking about this economist who went on and on about how advertising creates the desire for a product and so the product is produced as a result of the advertising ... and how if advertising didnt exist then the desire would not exist so there would be no need for advertising
and when it comes to things like teeth whitening strips i might understand ... but before there was the advertising some vain person had the need for perfectly shiny teeth without the huge expense of going to the dentist ... so the product was created and then in order to get the product out there they cant just stick it on a shelf somewhere ... they have to tell people somehow ... so then comes the advertising ... this economist has the story backwards ...
plus in his mind ... you can pretty much blame everything on advertising ... well if there wasn't an advertisement for oh i dont know mcdonalds ... maybe that person (who sued the pants off of mcdonalds for the hot coffee) wouldnt have gotten coffee that day ... maybe they didnt need coffee but they saw an ad and they suddenly woke up with the strong desire for a nice cup of mcdonalds coffee ... and they went out into the world and burned the shit out of themselves ... maybe they should have just sued the pants off of some rando ad agency for making them want coffee in the first place ... and maybe people will start suing ad agencies for making them fat too (i wonder if this has already happened) ... maybe i shouldnt been putting ideas like these into people's heads ... because it'll probably happen now ... SORRY (i swear im on your side here you ad people you)



ps ... i was reading about Generation O ... for fat ... in my adv ethics book and obesity in children is also advertising's fault ... as well as teen pregnancy and unemployment