The second tenet of Meliorism is a belief in the natural goodness of man, corrupted by society. This emanates from the work and thought of Jean-Jacques Rousseau. Rousseau transferred the struggle for good and evil from within the breast of the individual to society. Evil comes from society, and therefore, by fixing society — tinkering with society's traditions, customs, language, laws, and norms — we can eradicate evil. This social engineering will restore the natural goodness and natural equity of the world initially corrupted by society.
The conservative's counter-argument to these tenets and to Meliorism in general is what I've called "The Tragic Nature" of the human condition. The rebuttal to the first premise is that human nature is constant and not progressing. We, in the present, are not at all different — neither better nor worse — from our eldest ancestors. To the conservative, as Russell Kirk once explained, "real progress consists in the movement of mankind towards the understanding of norms, and towards conformity to norms."1
The norms of yesteryear are as applicable today as they were when first established by our ancestors. The farther we "progress" away from them, the worse our lives and civilizations become.
Here's an enlightening article about it: https://www.lifesitenews.com/opinion/the-bad-roots-of-progressivism-make-for-a-poisonous-tree