One underlying element is the awareness that thoughts are connected to actions. If we can legally prohibit certain actions, the Marxist Leftist Statist wonders, then surely we can also prohibit the thoughts and beliefs that are connected to those actions.
Thus the modern western world continues to slide into an Orwellian nightmare. But this reasoning is false, as follows:
Thoughts/beliefs are not equal to actions nor are they necessarily causal of actions, indeed the influence works both ways; but more importantly, there is a barrier separating the inner mental world from the outer world of our behaviors. This barrier is an essential aspect of what it means to be a self-conscious sentient and thinking being, it is also in part what it means to use language. The Leftist fails to see the existence and primary significance of this barrier, and thus confuses inner and outer as if humans had no experience with and responsibility for managing the operations of that barrier, as if it were not entirely necessary to who and what we are.
The Leftist wants to materially reduce down to the smallest iota of causality, because the Leftist is an empirical analytic posiivist and cannot separate out differences of category and quality. Marxism is actually in part an attack on the very structure of our psychology and consciousness, which can be seen by observing modern-day Leftists and their desire to regulate "hate speech" and "hate thought".