To penalize a woman, career-wise, for allowing her pregnancy to interfere with her job and the jobs of others is perfectly understandable.
That's what I'm arguing. That a woman who chooses to become pregnant, knowing that there is a very real potential it will impact her career (because it will interfer with her job, and the jobs of others), should be prepared to deal with the consequences. Not that she should be "penalized" but that she, by choice, may be making herself less competitive in her chosen career path.
To penalize all women -- declare them "unequal" -- because of their potential to get pregnant is like declaring a man unequal because of his potential to get prostate cancer.
A bit of a stretch based on what I said. You continually interchange the definition that unequal = unjust, whereas I'm arguing unequal = different. Truth be told, there are multiple definitions. Men and women are different, therefore in some circumstances, men and women are not equal. Take into account that I'm an engineer - so I tend to work in absolutes. Most men are not equal either. It's a fact of life. Unless we were all carbon copies of the same exect person...
You say that men and women are fundamentally different in "degree." I'm interested in how you define "degree," because Merriam-Webster is using it in the context of status and value. Again, I'm agreeing with you that men and women are different. And I appreciate that you feel that those differences aren't enough to merit unequal treatment in terms of employment, protection under the law, etc. I just don't see -- and have yet to be convinced -- that those differences in substance are enough to constitute inequality in value.
Again, there are numerous definitions of degree. According to OED degree: the relative intensity, extent, measure, or amount of a quality, attribute, or action. So, let's just use measure and attribute. Women have more estrogen than men. Men have more testosterone than women. So, women have a higher degree of estrogen then men, and men have a higher degree of testosterone than women. Now, put that back into the original definition of unequal. Men and women aren't equal, or they'd have the same level of testosterone and estrogen. Remember the use of the word "or", only one condition must be true for the entire statement to be true.
OED also describes equal: Possessing a like degree of a (specified or implied) quality or attribute; on the same level in rank, dignity, power, ability, achievement, or excellence; having the same rights or privileges. Again, multiple definitions... So while they should have the same rights or privelges, they may or may not have the same ability.