Original: There are theories which have developed a concept called human capital (referring to the skills that workers possess, not necessarily their actual work), although there are also counter posing macro-economic system theories that think human capital is a contradiction in terms.
Simplified: There are macroeconomic system theories which have created a concept called human capital (referring to the skills that workers possess, not necessarily their actual work), although there are also theories that think human capital is a contradiction in terms.