Answer:
Logical fallacies, although a bit illogical, can be effective. They can make arguments seem more persuasive. They also add emotion to the argument, which will make the opposer more convinced of an argument. In most ways, however they dumb down an argument and make the person using them look stupid.
If a person uses an illogical fallacy, it can instill fear into people, which is one of the best persuasive techniques. The fallacy called the "slippery slope", where a person claims that a single event will inevitably give rise to a chain of future events, is a perfect example of this. Someone could say that if Trump is re-elected, a chain of events will occur that will start WWIII. This instills fear in people, which persuades them to not vote for Trump.
