I was idly listening to the TV on a commercial channel and I noticed an advertisement for some unknown brand of generator. The words were all about how good and reliable the product is in language replete with "conviction". There was absolutely no reason to believe the ad. It was a clear example of unsubstantiated assertion. Apparently, we are expected to be convinced by some anonymous person telling us "facts" about a product without any supporting evidence.
This ad was one step further down the slippery slope of rank assertion than the current crop of ads for hair shampoo. They claim, again without any supporting evidence, some numerical value, usually some odd number like 69%, for the improvement in strength or smoothness or shininess resulting from the use of the product This is presumably an attempt to imply that some measurements have been done and that these 'measurements' are real evidence for the claim.The latest example of this kind of advertising come from recent TV ad which features a young woman who asserts that she knows what is best for for her and implies that, unless we follow her choice of product, we will be treating ourselves less well than she treats herself. What unmitigated gall. She was, after all being paid to read a script written by someone else. I assume that the advertising "experts" have worked out that for everyone like me who is repulsed by the ad, there and many people who will be convinced by it to buy the product. If this is so, it is a sad reflection on our society.
I guess that that advertising industry is employing 23 year old marketing graduates who 'know' what words 'work'.
I was taught that there are three proper purposes for a speech or a piece of prose; to persuade, to instruct or to entertain. Advertising should certainly aspire to persuade, it may need to instruct and it probably works best by being memorable if it also entertains. The process of instruction only works if the authority of the instructor is established; the art of persuasion requires the persuader to gain the respect of the listener or reader. Neither of these two things happen just because somebody asserts something. It seems to me that the advertising industry does not respect its audience when it assumes that assertion is all that is needed to persuade us to buy the advertised product.
The advertising industry is not the only section of our society which relies on assertion. Our politicians today seem incapable of either instructing or persuading us. There is a theory that everything said in public by politicians these days is preordained by spin-doctors whose job it is to advise on the choice of words so as to avoid any unwanted inference.