For philosophy and history alike have taught...to seek not what is "safe," but what is true. - Henry Sidgwick

[T]he history of thought […] reveal[s] discrepancy between the intuitions of one age and those of a subsequent generation. But where the conflicting beliefs are not contemporaneous, it is usually not clear that the earlier thinker would have maintained his conviction if confronted by the arguments of the later. The history of thought, however, I need hardly say, affords abundant instances of similar conflict among contemporaries; and as conversions are extremely rare in philosophical controversy, I suppose the conflict in most cases affects intuitions—what is self-evident to one mind is not so to another. It is obvious that in any such conflict there must be error on one side or the other, or on both. The natural man will often decide unhesitatingly that the error is on the other side. But it is manifest that a philosophic mind cannot do this, unless it can prove independently that the conflicting intuitor has an inferior faculty of envisaging truth in general or this kind of truth; one who cannot do this must reasonably submit to a loss of confidence in any intuition of his own that thus is found to conflict with another’s.

It is sometimes said that we live in an age that rejects authority. The statement, thus qualified, seems misleading; probably there never was a time when the number of beliefs held by each individual, undemonstrated and unverified by himself, was greater. But it is true that we only accept authority of a peculiar sort; the authority, namely, that is formed and maintained by the unconstrained agreement of individual thinkers, each of whom we believe to be seeking truth with single-mindedness and sincerity, and declaring what he has found with scrupulous veracity, and the greatest attainable exactness and precision.

I may begin by laying down as a principle that ‘all pain of human or rational beings is to be avoided’; and then afterwards may be led to enunciate the wider rule that ‘all pain is to be avoided’; it being made evident to me that the difference of rationality between two species of sentient beings is no ground for establishing a fundamental ethical distinction between their respective pains.