Proponents of the tripartite system consider the arguments brought forward by the critics to be invalid. They point to the fact that not only Gymnasium, but also comprehensive schools and schools serving mature students such as the "Kolleg" or the "Berufsoberschule" offer the possibility for the "Abitur". Also it is possible to attend college without holding the "Abitur". They also hold the opinion that state-funded "Realschulen" and Gymnasiums offered many working-class children the possibility to move up the social ladder. Also, proponents of the tripartite system fear the abolishing Gymnasia and "Realschulen" will lead to the growth of a private school sector.