If you look down on half the human race for their inborn nature, you present yourself as no friend of humanity. You know many members of the opposite sex who contribute to society more than members of your own. This should hint that inferiority is not caused or overcome by gender. It is an inconsistent view to hold that one sex is innately born better than the opposite sex.
Hypothetically, even if you’re smarter than every woman you have ever met, it is unfair to the one woman out there who might be smarter than you to declare your superiority (and if you’re a sexist she is most certainly out there). The problem with sexism is it’s too easy of a view. It’s a final solution. It proudly claims too much. What kind of reasoning is it to say, “I deserve more freedom than these people who are different from me, and my entitlement is caused by said difference.” Only a very weak mind is seduced by such self-serving reasoning.
If you search through history, these elitist principles are often shared by societies that either fail, grow out of it, or remain today as one of those societies you wouldn’t want to live in. If your absolute rule is reminiscent of failed principles and cannot be justified by any claim other than it simply is, you should be ashamed to think you found such an absolute principal. Sexism cannot defend itself in a court of logic. Gender prejudice goes against the concept of the individual, of which our entire pattern of thinking is based on (from this we derive the ideas of morality and freedom to begin with).
Men and women are equal but different. Neither of us deserve special treatment, but we both deserve fair treatment. There are too many good ideas out there to leave any room for one as useless as sexism.