To avoid an argument, simply stop the conversation.

Personally, I do hate arguments. Most especially, if it's nonsense. Answering the question, "how to avoid an argument?", is just a question back, "what made the argument?" Isn't it the conversation?

Usually, people tend to behave in a manner that they know everything even though they not. This may be the person who used to start an argument. The person may be a real pretender who is tending to be well-good enough to handle everything under the sun, yet he is not. Someone who doesn't know the humbling of himself. And, if you happen to encounter such a person, avoid to have a long conversation with him. Because, no doubt, in the mid of your talkings, he will insist and insist his minds for he's confidence to know everything.

That will work. Try it out.