OK, GoR, want to explain how the above is defensible?
So I guess Ill respond here by posing some questions, you dont have to answer all of them but they can frame the discussion that will ensue
1) Using the example he listed do you think that the difference in the number of chemical engineers we have who are women vs men is due to factors that are "unjustifiable"? Are the differences due to "unfair discrimination" in your mind?
2) Do you believe each gender has certain strengths and weaknesses that differ? If so, isnt it possible that these manifest themselves in such a way that more men are deemed desirable for chemical engineering jobs than women?
Look I know very little about chemical engineering specifically and what a successful Chem engineer entails but that's largely besides the point here. Each gender has their strengths and their weaknesses. If you dont like the idea specifically that "one gender has better visuospatial skills" and that is the reason for why one gender should be picked above the other that's fine. But other factors that arent as simple as "visuospatial skills" can be found to be different between genders and if the male gender is found to be more likely to have those desirable skills for a ChemE position, shouldnt it then be justifiable that more men are chosen than women?
Likewise in a more relevant example to medicine, 75% of pediatricians and 85% of OB/GYN doctors are female. Part of this is females are more likely to be comfortable with such positions. But do you think this gap is just due to women being more comfortable than men in OB/GYN or are there other factors at play such as maybe women are more likely to have skills needed for the field than men? My guess is there are multiple factors at play.
The key thing here is not to speak in absolutes. Do I buy there is some discrimination against women in the field of engineering and getting jobs? Yes, I think there is a fair chance that is true. But is it possible there are multiple factors at play that the reason for the gap in ChemE men vs women? Ie that it isnt just due to pure discrimination against women but also due to the idea that men might be more likely to have characteristics needed for success in the field than women? I think the answer to these questions is potentially yes as well. Again, I dont really know enough about the field to answer unequivocally but I dont think the gap is due just to "unfair discrimination".
At the end of the day you have to also ask yourself what value do you see in their being equal representation of men and women in a job like chemical engineering? What are the values to the field of chemical engineering itself for this, particularly if there is evidence(and Im not saying there is I have no idea) that men are more likely to have characteristics necessary for success in the field than women?