I
t is underappreciated in investigating the causes of disagreement the extent to which whom we trust influences what we believe. It is all too easy to assume that belief consists in independent assessment of available evidence, plus inherent personality traits—this allows us both to flatter ourselves that we are utterly "rational", while getting to color our opponents as either stupid or basically immoral.
In fact, the world is a complicated place, and we rely to an extraordinary extent on trust of other people both to deliver what evidence we even permit ourselves to consider, and how to interpret that evidence. A great deal of the arguing that goes on the world accomplishes very little for several reasons, but not least among them is the fact that sides in arguments are typically starting from radically different places of trust.
Why do we believe the people that we do? Typically, we believe those whom we perceive to have done good for us. Parents are highly trusted by young children, because those children see the good that is done to them from their parents. As humans grow into maturity, their circles of trust grow with them, as they experience good and bad things from more and more people.
It may sound like I'm saying that intellectual arguments, and indeed truth, have nothing to do with what people believe, but only arbitrary relationships of those who happen to have helped us in the past. However, giving someone the truth is in fact a recognizable good that humans respond to. It often happens that one will be confronted with some intellectual or moral difficulty in their lives, only to find help resolving it in a book. Thus we can add people to our trust networks whom we have never even met.
Imagine the difference in trust of the American medical system between someone whose mother was a doctor, versus someone whose father was bankrupted with medical bills. In theory, these two people could have access to the exact same evidence, and yet we would expect very different attitudes from them toward statements from the medical establishment. Or, consider the difference between someone whose early experiences involved excelling in the sciences at school, versus someone with a positive upbringing in an Evangelical Church—the latter will likely have a very different reaction to perceived conflicts between evolutionary theory and certain interpretations of the Bible.
Obviously, people's are occasionally reachable by argumentation alone, but these events are rarer than one might think. The most effective forms of persuasion have a tendency to be long-term, and often involve becoming friends with those with whom one disagrees. It is when trust is formed between two people that the truth has the best chance of coming out.
Figure out whom a person trusts, and why. Attacking a person's beliefs directly is usually more of a power-play than a charitable act of truth-seeking. Commit to arguments taking years, not minutes, and commit to loving your enemy. Put down your swords and your hot-takes, and, especially, consider how you might be the one in the wrong.