I would say Temporal is not far off in saying "commitment to the truth," but I would go further and say that the core of humanity, of being human, is striving towards bettering ourselves through the application of intelligence. Intelligence is the human superpower and when harnessed it can create incredible things.

Doing the reverse of empowering your intelligence, and empowering your confirmation bias (as comment parent), tribalism (as Donald Trump/neo-nationalists everywhere), or credulity (as meditationists/"everything is connected maaaaaan" types), is worse than suicide. You're using the power of your brain to enhance its flaws and create a perverted version of a human, progressing, but in the opposite direction; becoming stronger, but in a domain that should be avoided at all costs.

This is somewhat like the process of building a good military sniper by progressively dehumanizing them, stripping them of their empathy and agency in order to use them as an efficient killing machine. But worse, because you can think yourself out of that -- you can't think yourself out of a totally broken mind, and the more intelligent you are, the better you are at keeping yourself broken.