Conjectures, especially where infinity is excluded from the Divine attributes, may perhaps be sufficient to prove a consistence, but can never be foundations for any inference.
There seem to be four circumstances, on which depend all, or the greatest part of the ills, that molest sensible creatures; and it is not impossible but all these circumstances may be necessary and unavoidable.
We know so little beyond common life, or even of common life, that, with regard to the economy of a universe, there is no conjecture, however wild, which may not be just; nor any one, however plausible, which may not be erroneous.

All that belongs to human understanding, in this deep ignorance and obscurity, is to be sceptical, or at least cautious, and not to admit of any hypothesis whatever, much less of any which is supported by no appearance of probability.

Now, this I assert to be the case with regard to all the causes of evil, and the circumstances on which it depends.

None of them appear to human reason in the least degree necessary or unavoidable; nor can we suppose them such, without the utmost license of imagination.
The first circumstance which introduces evil, is that contrivance or economy of the animal creation, by which pains, as well as pleasures, are employed to excite all creatures to action, and make them vigilant in the great work of self-preservation.

Now pleasure alone, in its various degrees, seems to human understanding sufficient for this purpose.