Nussbaum is using rational means of persuasion. She is talking about sustainability and a better society in the democracy. It is only possible when the difference between classes are reduced, income disparity among people are eliminated and each class helps others in growth and development. It will increase cohesion and harmony in societies that is the basic constituent of the democracy.
Not doing so, will create huge differences in different classes of people full of frustration. It will lead to anarchy and it will put value of democracy in doubt.
It is relevant because it is very important understand the viewpoints of others in the classroom or the workplace. It is the basis of the promotion of original ideas, creativity and innovation. It is the reason, why diversity at workplace is being promoted. When people from different background, come together and propose different views towards the same situation, then it creases the value of the workplace culture. It helps in analyzing each idea and the best idea is selected. Hence, innovation is promoted. Here, the most important aspect is to recognize the views of others that are different and respect it.
Critical thinking helps in analyzing the scenario and coming up with the best possible solutions to improve the organization, society and or any other entity. It helps to take decision regarding what should be or should not be done to pursue the long term sustainability. It means that the critical thinking pushes towards the continuous improvement and evolving system. Hence, it owns significant value for the system.