“It is very clear to me,” he wrote, “that, as Beelzebub is not to be cast out by Beelzebub, so morality is not to be established by immorality.  It is, we are told, the special peculiarity of the devil that he was a liar from the beginning.  If we set out in life with pretending to know that which we do not know; with professing to accept for proof evidence which we are well aware is inadequate; with wilfully shutting our eyes and our ears to facts which militate against this or that comfortable hypothesis; we are assuredly doing our best to deserve the same character.”

Freedom of thought meant for Huxley all that is best in liberalism applied to life.  In an essay on Joseph Priestley, he described the condition of affairs in England last century, when scientific investigation and all forms of independent thinking laboured under the most heavy restrictions that could be imposed by dominant ecclesiastical and civil prejudice.  He pointed out the astounding changes between these times and the times of to-day.

“If we ask,” he wrote, “what is the deeper meaning of all these vast changes, there can be but one reply.  They mean that reason has asserted and exercised her primacy over all the provinces of human activity; that ecclesiastical authority has been relegated to its proper place; that the good of the governed has been finally recognised as the end of government, and the complete responsibility of governors to the people as its means; and that the dependence of natural phenomena in general on the laws of action of what we call matter has become an axiom.”

The common ground of those who advocate the duty of belief and those who insist on the duty of doubt is clear.  Both are agreed as to the necessity of accepting whatever has sufficient evidence to support it; both agree that there is room for doubt though not necessarily for rejection in cases where the evidence is contaminated or insufficient.  It is in the application that the difference lies.  The scientific theologian admits the agnostic principle, however widely his results may differ from those reached by the majority of agnostics.  “But, as between agnosticism and ecclesiasticism, or, as our neighbours across the Channel call it, clericalism, there can be neither peace nor truce.  The cleric asserts that it is morally wrong not to believe certain propositions, whatever the results of a strict scientific investigation of the evidence of these propositions.  He tells us that “religious error is, in itself, of an immoral nature” (Newman).  It necessarily follows that, for him, the attainment of faith, not the ascertainment of truth, is the highest aim of mental life.”

Huxley helped largely in the modern movement which has made it impossible to blame people for doubt, and this was what he strove for most strenuously.  Freedom of thought, like freedom of the Press, by no means implies that what is free must necessarily be good.  In both cases there may be a rank growth of weeds, nurtured in vicious imagination, and finding a ready market with the credulous mob.  For the detection and rejection of these, the critical method of science serves as well as it does against the loftier errors supported by authority.