John Stuart Mill

The object of this Essay is to explain as clearly as I am able, the grounds of an opinion which I have held from the very earliest period when I had formed any opinions at all on social or political matters, and which, instead of being weakened or modified, has been constantly growing stronger by the progress of reflection and the experience of life: That the principle which regulates the existing social relations between the two sexes—the legal subordination of one sex to the other—is wrong in itself, and now one of the chief hindrances to human improvement; and that it ought to be replaced by a principle of perfect equality, admitting no power or privilege on the one side, nor disability on the other.

In all other cases, the burthen of proof is supposed to lie with the affirmative.

Again, in practical matters, the burthen of proof is supposed to be with those who are against liberty; who contend for any restriction or prohibition; either any limitation of the general freedom of human action, or any disqualification or disparity of privilege affecting one person or kind of persons, as compared with others. The à priori presumption is in favour of freedom and impartiality. It is held that there should be no restraint not required by the general good, and that the law should be no respecter of persons, but should treat all alike, save where dissimilarity of treatment is required by positive reasons, either of justice or of policy.