I like to ask people who believe in reality the following question: “What is the one single piece of evidence that convinces you that reality is real?” The answer is always easily debunked. For example:
“Evidence”: Reality is real because I can sense the world around me.
Answer: Senses have been known to fool people, quite often.
“Evidence”: Reality is real because if I base predictions on my understanding of it, they are generally accurate, so my understanding of it is probably pretty accurate.
Answer: Predictions are not evidence.
“Evidence”: When people from entirely different backgrounds and personal histories and different parts of the globe compare notes, they find that their realities are fundamentally the same.
Answer: Since when is a sample size of “2″ acceptable for anything?
“Evidence”: Reality is internally consistant.
Answer: So are mirages.
“Evidence”: Math based on simple observations of the universe requires reality to be real.
Answer: Since you don’t understand the math it would be all to easy for you to be fooled by this.
For more on how reality is not real, see this post by S. Fred Singer