PerspectiveI think when we meet people in person we subconsciously cold read them, and determine what kind of lingo they would understand, whether they are okay with swearing, whether they are likely Christian or Muslim, or whether they would rather watch Idols than Attenborough. Online these things are harder to guess. Facebook has the profile area that lays a lot of that stuff bare, but even then I think an incomplete picture forms. In person we also have the luxury of proximity. People around us share some of our experience, and they draw from the same experiences, whereas people from other countries have much different experiences. I find it hard to properly communicate South Africa, because our country is such a strange place. There are billionaires and people dying of hunger, top universities and mud schools, mansions and shanties with bucket toilets.
True motivesWhen an opponent says X, what they really mean is "I believe X is true because of Y". X is not important here, Y is. Y is often a feeling, but nobody wants to really admit that most of their answers are based on mere feelings. They construct elaborate defenses around Y to hide it from daylight, but when you know your opponent it becomes clear what Y is. For example:
X = "Prostitution should remain illegal"
Reason A="Prostitutes spread diseases and there will be more disease if it is legal"
Reason B="Prostitution degrades women"
Reason C="Legal prostitution makes it okay to objectify women"
Reason Y(The real reason)="I am disgusted by prostitutes" or "The bible says prostitution is wrong"
A, B and C are just cover ups, and knowing your opponent helps you to realise that. Most people rationalise their position after picking it, and don't actively seek rational positions. They usually fight with tooth and nail because below all their useless arguments lie a deeply seated emotional reason for wanting their position to be true. Understanding your opponent then is not only a good idea, but vital. It is probably wiser to abandon the argument if your opponent is unable to overcome their own emotional reason for believing in their position. I have made the mistake of trying again and again too many times.
PersonalityAddressing someone is easier if you know what they are like. Like it or not, we adjust our behaviour to suit others when we are around them. This is not because we are fake or pretentious, it is merely a courtesy we extend to our fellow humans in order to make relating easier. They then return the favour by toning down their personality to suit you. Without understanding the nature of your opponent it is difficult to level with them. Personality makes a major difference in how we see the world.
I am myself quite withdrawn and pessimistic in general. If someone calls me friend or tries to contact me in a personal way too soon I withdraw more, and basically distrust that person. After all I wouldn't make friends that easily, they must want something! An extroverted optimist may not see things my way. If we fail to find common ground I will just seem paranoid and quiet and he or she will seem loud and untrustworthy. In online discussion we pretty much lose the personal interaction, and try instead to address each other as data points.
Personality gets lost in this mush because it is not something you can communicate with text only. Small body language cues and facial expressions speak to us when we interact with people in the real world. Online we don't see that, so the automatic assumption(maybe) is either that a person is like me or not like me. I think of this as a me/anti-me dichotomy, but maybe there is some technical term for it.
ConclusionBased on the three problems above we can easily move forward if we try to understand the perspective of others. Knowing about how their locale, job, or religious affiliation is helps, and so does asking. European people referring to poverty may think of it as malnutrition, whereas Africans know it as death and disease. Roman catholics are bound to ceremony and undying respect, whereas evangelicals are loud and outgoing. Even atheists may carry some vestige of attitude from their religious surroundings or upbringing, all of it has to do with culture. Culture has no impact on our personalities, but it has a significant impact on how we express them.
Finding the motivation for beliefs is tough. People hide their motives, and are quick to spit out regurgitated defences or pseudo reasons for their positions. The only real way to get the information is to carefully craft questions that reveals motive. I have noticed that thought experiments, something I use extensively for self discovery, also helps to discover others. "What if mary was a prostitute?" "What if a prostitute had two children to feed after her husband left her, and that was the only way she could make ends meet?". Questions like that displace prejudices by forcing moral decisions. In other words: what is worse, children with malnutrition or a woman in prostitution? Someone who is deeply emotionally disgusted by prostitution happily sacrifices the good nutrition and schooling for the children, or they try and find loopholes, or make unimaginable leaps like solving world hunger. I think in reality they would not do that, but that is another story. The emotional backdrop of ideology can swiftly be crushed by reality.
When it comes to personality we should dissociate ourselves from others and try to see them as black boxes. Without the guiding light of knowing them personally it is difficult to draw conclusions. I have seen too many instances of a "Oh you must be an X!" getting an emphatic no from the person being called an X. We just lack sufficient information about a person online to draw any meaningful conclusions about what or who they are. We should spend some time trying to find out more and not just hopelessly bash at silly arguments that are essentially lost in translation.