This essays by G. K. Chesterton speaks to the blindness that often underlies disagreements.
Why do people think it intelligent to say, “I can see no difference!” It is nowadays quite a mark of culture to say that one can see no difference between a man and a woman, or a man and an angel, or a man and an animal. If a man cannot see the difference between a horse and a cow across a large field, we do not call him cultured; we call him short-sighted. Now, there are really interesting differences between angels and women; nay, even between men and beasts, and all such things. They are differences which most people know instinctively, as most people know a cow is not a horse without looking for its mane; or most people know a horse is not a cow without looking for horns. Whether the difference ought to count in this or that important question is a completely different matter, but it ought not really to be so difficult simply to see the difference.
Such things can only be argued upon commonplace if imaginary examples. Let me suppose that one modern matron says to another: “I don’t like my daughter playing hockey.” It is very probable that the other modern matron (being a yet more modern matron) will answer, “Well, you let her play lawn tennis; and I don’t see the difference.” It is even more probable that the less modern matron will simply collapsed under this, and be found incapable of reply. For this is a strange epic; and while, in some ways, we’re quite dangerously encourage the appetites, we have quite ruthlessly crushed the instincts. The right answer to the more modern matron (which the less modern matron so lamentably failed to give), is simply to say this, “If you really cannot see the difference between hockey and lawn tennis, I suggest that you try using your brains until you do. For the differences, I assure you, are both enormous and subtle.”
…What is called the old-fashioned idea of woman may be stupid; but it cannot be stupider than the people who cannot see that lawn-tennis falls within its frontier, and hockey outside it. What is called a new idea of woman may be more intelligent; but if it is even feebly intelligent it will instantly “see the difference” between lawn-tennis and hockey.
…Now, I’m not urging these things as any argument against the girls playing hockey. I am urging them as in argument against the modern matron’s “not seeing any difference.” If anyone choose to say, “I do to the difference; I prefer the hockey girl” — that is entirely intelligent. But if modern thought merely classes all games for girls together, then there is only one explanation to be offered: is simply because modern thought means modern thoughtlessness.