I'm no expert on these questions, or related issues, but as a theologian and a person wanting to understand and submit to the Catholic Church on the questions of religious liberty and conscience, I think that the Church has decided that, while a free conscience in error in questions of faith or morals isn't completely free, in light of the soul's true end, the possibility of error is preferable to compliance by compulsion. That is, assent compelled--either to the dictates of right reason, or to those of revealed truth--is itself contrary to charity. The existence of error, and the willingness to tolerate it in some sense, is not to say that truth and error are indistinguishable. Also, "Ultimate truth does not exist" is a statement expressing epistemic skepticism, and is not equivalent to, "People are free to make their own decisions and moral choices." Acknowledging the plain reality of misused freedom is not the same as endorsing freedom that has been...
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