This affirmation reflects the humanist inheritance from the scientific revolution and the Enlightenment, and it underlies the movement's defence of science, education, and civil liberties. It stands against the appeal to unquestionable authority found in dogmatic systems, religious or political, and it connects to the humanist principle that belief should be proportioned to evidence. The commitment to free inquiry is central to secular humanism's self-understanding as a reason-based life-stance, and it is presented here as a value its adherents hold.
The institutional ancestry of this principle runs through nineteenth-century British secularism, especially Charles Bradlaugh, who founded the National Secular Society in 1866 and later fought a prolonged constitutional battle for the right to affirm rather than swear a religious oath on taking his seat in the House of Commons, to which he had been repeatedly elected from 1880 only to be repeatedly barred; the dispute was finally resolved by the Oaths Act 1888, which allowed a secular affirmation in place of a religious oath. Bradlaugh's case became a landmark demonstration that the abstract principle of free inquiry had concrete civic stakes, since it directly determined whether a non-religious citizen could hold public office on equal terms with religious colleagues.