Pessimism is a vague word.
It does not represent one philosophy, but several; and before we, in any case, reject its claims on our attention, we should take care to see what its exact meaning is.
The views of life it includes may be classified in two ways.

In the first place, they are either what we may call critical pessimisms or prospective pessimisms: of which the thesis of the first is that human life is essentially evil; and of the second, that whatever human life may be now, its tendency is to get worse instead of better.

The one is the denial of human happiness; the other the denial of human hope.

But there is a second classification to make, traversing this one, and far more important.

Pessimism may be either absolute or hypothetical.