By definition, a logical fallacy is a flaw in reasoning, for example a ‘slippery slope’, a middle ground. I will be looking at appeal to (improper) authority – saying that because an authority thinks something, it must be true. For example, using a celebrity to endorse a product; someone who many people see as an authority will encourage or convince them to buy a product, which allows the company to capitalise from logical fallacies. This can also be applied to expert endorsement, e.g. ‘9 out of 10 dentists recommend…’ and so on.