In this study we propose a dichotomy in the strength profile of tectonic plates. This apparent dichotomy suggests that plates at the Earth's surface are significantly stronger, by orders of magnitude, than the subducted slabs in the Earth's interior. Strong plates promote single-sided, Earth-like subduction. Once subducted, strong slabs transmit dynamic stresses and disrupt subduction. Slabs which are weakened do not disrupt subduction and furthermore exhibit a variety of observed morphologies.