It’s safe to say you’re right if the numbers support what you believe. But in order to really be safe, you have to go a bit further. People will always find a way to interpret facts to support a conclusion they’ve already made. As one person said in regards to this (amazing) post, “If a long, well-reasoned article could actually win the debate, the debate would have ended a long time ago.” That’s why you have to have ideas in the abstract backing you up, a philosophy that is the root of all your positions.
The post was about the Second Amendment, so I’ll first use that as an example. On all sides of the “gun control” debate, people will cite facts. Sometimes, naturally, they will cite lies – but let’s accept that many times all sides are presenting true, documented facts. And they are all picking and choosing numbers about how the rates of firearm ownership correspond with rates of violent crime from country to country (and sometimes city to city or state to state), selecting only those that make their side look right, and leaving out the numbers that don’t. Some countries in which firearms are banned have less crime than countries where they are widely available. In some places, firearm possession is high but crime is low or no higher than places where no one or hardly anyone has them. So whose side do you choose to take? There is still a conclusion to be drawn from this – that the availability of firearms is not the only factor in violent crime rates and so reducing the availability of firearms will not guarantee a drop in violent crime. But is that enough? I don’t think so. The root of your position cannot be numbers. What are your principles? What do you believe justifies violating someone’s rights? What justifies taking a law-abiding citizen’s possessions? What justifies inhibiting somebody’s ability to own something they want? What justifies removing a means of defense of his life, his liberty, his property, or that of others? Now you see that you need not only ideas, but facts, and you need not only facts, but ideas. Otherwise, your side may lose to another side that has documented facts, too. Otherwise, the philosophy of natural law may lead you down a slippery slope into regarding property rights as absolute, into asking why the government has a right to stop you from owning drones or tanks or chemical weapons or whatever you want provided you’re rich enough to own it – I don’t think you will actually start to believe this, but you run the risk of having your argument for firearm ownership ridiculed. People will ask you why the government should not stop you from owning certain types of weapons if they can stop you from owning others, and you must respond with facts of your own.
Of course having both abstract ideas and facts on your side has to do with multiple issues. It can be a defense of free markets – yes, people prosper when the government gets out of their way, but there is a deeper reason to support a free market. That is the rights of people to control what they do with their property – who they sell their labor too, who they sell their goods to, who they buy their goods from, how much of their money they spend, and so on. It is, essentially, people’s freedom.
The general question of why you believe what you believe should have to do with both philosophy and empirical evidence. If one is under attack, you can still defend your positions using the other.