Inclusiveness is radically inconsistent with free thought and speech. The problem is quite fundamental. To question the principle of equal inclusion is to put some people's standing in question and ipso facto to exclude them from full equality with those whose standing is not in question. A regime of inclusiveness must therefore suppress questioning of its principles if it is to exist at all.
More generally, every system needs standards and restrictions, and doing away with some makes others more important. For that reason, expanding some aspects of diversity means limiting others. In particular, making ethnic and sexual diversity a supreme value means limiting permissible opinion quite radically. If it is unshakable dogma that group differences never cause problems, and they obviously cause problems, there are going to be severe limits on thought and discussion so the problems can't come up.
In some ways suppression of discussion seems odd as a response to the reality that diversity means differences that matter. After all, liberals believe in science and rationality, and science and rationality tell us men differ. Why not face up to the situation and make the best of it? Whether the goal is inclusiveness or anything else, we are more likely to realize it if we understand the world as it is. Or so it would seem.
The problem is that modern faith in science is more than acceptance of the value of modern science. Together with liberalism, it forms a comprehensive approach to life. Educated people today look to the two for everything they need to know, because nothing else has public validity. For that reason those principles must satisfy demands that are not specifically scientific. They must provide satisfying ways to deal with the problems of life generally, and thus function together as a religion.
That religious function means that liberalism and faith in science--I'll call it "scientism"--make certain demands on the world. A religion of sin and redemption makes no sense in a world of perpetual this-worldly progress. In the same way, a utopian religion, or a utopian scheme of thought that functions as a religion, makes no sense if the world resists human wishes in basic ways. It must insist that the world is such that its outlook on things makes sense.
Scientism insists on treating politics and morality as part of nature, as it understands nature. It therefore excludes natural harmonies and transcendent principles, and treats logic, desire, and means-ends rationality as the only rational guides to action. The result is a tendency to treat conflict as the basic social reality, since desires conflict, and to explain all human things by reference to the physical side of life.
Those who accept scientism and admit the reality and significance of group differences are therefore likely to be tempted by the view that the conflict among biological groups is the ultimate human reality. Hence the outrage among liberals in response to any suggestion that there are group differences that matter. If you accept that such differences exist, it is thought that you will logically be impelled to embrace something like Nazism.
For its part, liberalism tells us that our good is living by our own rules and getting what we want. For that reason, it must give people who make pleasing themselves their supreme goal reason to submit to its authority.
To do so, it must tell them that if they go along they will get along. Liberalism's own principles justify resentment, resistance, and rebellion by people who have enduring reason for dissatisfaction. Even if unsuccessful such a response would vindicate their autonomy and therefore their human dignity.
A situation in which basic social principles support rejection of the social order would be intolerable for any government, especially a liberal government that claims to govern by consent and strongly prefers minimal use of overt force. For that reason, liberalism cannot admit that there are irremediable evils and inequalities.
It especially cannot accept that there are intractable human differences in qualities like intelligence. Liberalism is based on human autonomy, on our ability to decide for ourselves what we will be. If some are intractably different from others in ways no one would choose for himself, autonomy is a mirage, and liberalism makes no sense. Liberals obviously cannot accept such a result, so it must be false, and if it isn't false it must be made false as a social matter. In other words, we must all be forced to live by a lie.