The thought of the thought in itself offensive to thought is the thought in itself offensive to thought.
For thinking, every thought as thought is already the thought of its negation. The thought of a thought offensive to thought is the thought offensive to thought. The thought of an existent evil presumes the existence of a will that sought or seeks in the evil a good. Slavery and genocide and the torture of infants for fun, to be meaningfully denounced, must be thought supremely desirable, as the first two are: To be served unhesitatingly and unstintingly, to have all of one’s enemies, or the obstacle of the others, annihilated. The third is not subject to meaningful denunciation, since as a practice it has never had a constituency.
The notion of a thought universally offensive or offensive in itself is an impairment or obstacle to free thinking – or a position contrary to the orientation of thinking as end in itself, which is another description of the commitment to the search for truth.
So, the problem always initially presents itself as a conflict between some notion of a commitment to the search for truth and some notion of commitment to the realization of the good, or usually some particular good or set of goods deemed necessary or indispensable. Sooner or later, the latter position must win, but the victory must remain complete for precisely no time at all, until the end of time.