# Why does neoclassical economics assume preferences are fixed and exogenous in nature?

Why does neoclassical economics assume preferences are fixed and exogenous in nature? Is this because it's just a convenient assumption to make?

Does this link with the idea of "De Gustibus Non est Disputandum" (tastes are not a matter of dispute), if so, how?

Surely it isn't accurate to say that preferences are fixed when societal influences can easily change the preferences of individuals (e.g. through herd mentality etc.)?