Recently my working definition of 'political opinion' became "which parts of reality did the person choose to ignore". At least this is my usual experience when debating with people who have strong political opinions. There usually exists a standard argument that an opposing side would use against them, and the typical responses to this argument are "that's not the most important thing; now let's talk about a completely different topic where my side has the argumentational advantage". (LW calls it an 'ugh field'.) Sometimes the argument is 'disproved' in a way that would seem completely unsatisfactory to people who actually spent some time thinking about it, but the point is that the person has displayed the virtue of "engaging with the opponent's argument" which should finally make you stop talking about it.

Note that this is a general complaint about human behavior, not any specific political side, because this mechanism applies to many of them. Generally, 'true belief' sustains itself by filtering evidence; which is a process painfully obvious to people who filter evidence by different criteria.

More specifically, after reading the essay Economic Inequality by Paul Graham, I would say that the really simplified version is that there are essentially two different ways how people get rich. (1) By creating value; and today individuals are able to create incredible amounts of value thanks to technology. (2) By taking value from other people, using force or fraud in a wider meaning of the word; sometimes perfectly legally; often using the wealth they already have as a weapon.

It should be obvious how focusing on one of these groups and downplaying the significance of the other creates two different political opinions. Paul Graham complains about his critics that they are doing this (and he is right about this), but he does the same thing too, only less blindly... he acknowledges that the other group exists and that something should be done, but that feels merely like a disclaimer so he can display the required virtue, but his focus is somewhere else.

I am not blaming him for not solving all problems of the world in a single article, but other articles on his website also go in the similar direction. On the other hand, maybe that is merely picking one's battles; he wants his website focused on one topic, the topic where he makes money. So I'm not sure what exactly is the lesson here... maybe that picking one's battles and being mindkilled often seem similar from outside? (If I would know Paul Graham in real life, I could try to tell the difference by mentioning the other aspect in private and seeing whether he has an 'ugh field' about it or not.)