Greek rhetoricians had a practice called Dissoi Logio. The practice involved arguing both sides of an issue in order to obtain a deeper understanding of it. I enjoy practicing this because it not only helps develop a deeper understanding of an issue, but it also helps demonstrate that truth isn’t as absolute as commonly assumed.
One of the best tools available to assist in this practice is statistics. If you follow any online argument long enough, you get to the point where both sides are throwing statistics at each other. A good example of this is the debate around gun restrictions. Those in favor of gun restrictions will toss around comparisons of violent crime statistics between countries with strict and loose gun control laws. People opposed to gun restrictions will then rebut by throwing around statistics involving defensive uses of guns and point out that since the definition of violent crimes differ from country to country, comparing said statistics isn’t an apples to apples comparison. Your perception of which side is telling the truth is usually decided by your personal biases.
This is also common with economic arguments. For example, any argument about minimum wage laws inevitably involves supporters citing statistics that predict economic benefits from doing so and opponents citing statistics that predict economic problems from doing so. Which set of statistics you decide to cite as truth will likely depend on your economic biases.
Statistics aren’t the only tools available to assist you with this exercise, but I cite them because they are becoming one of the most common foundations upon which arguments are built. Starting this exercise by wielding statistics provides a lot of bang for your buck. Once you’ve done that, you can start looking at other argumentative foundations and master their uses too.
Even if you don’t decide to start with using statistics, I urge you to practice Dissoi Logio. Your initial attempts will likely be half hearted because most people aren’t taught the practice and the act of successfully arguing against your own position can be disturbing. However, practice makes perfect. The more you practice it, the better you will become. Eventually you should be able to make very strong arguments for and against any position. This will give you a leg up when debating because you will likely enjoy a better understanding of both your position and your opponent’s position than they do. It will also hopefully help you realize that truth and lies aren’t as black and white as most people mistakenly believe, which should make you far less susceptible to propaganda.