“Davies on Evil Suffered” | Prof. Edward Feser, May 2017  (full blog available here).

. . .[Two important] points about evil suffered.  First, it is a privation rather than a positive reality.  Second, it is not willed by God as an end in itself, but only as a concomitant of some good.

By way of illustration of these ideas, let’s suppose that in the course of giving a philosophy lecture, I begin to draw a circle on the marker board but do not complete it, so that the resulting figure looks like a C.  The circle is a bad or defective circle, and insofar as I am the cause of it, what I have caused is therefore something that exhibits badness or defect.  But strictly speaking, the badness does not amount to some positive feature I have put into the circle.  Rather, it amounts to the absence of some feature that I could have put into it and that a complete circle would have had.  The badness is a privation rather than a positive reality.  

Strictly speaking, then, I have not caused any badness to exist.  Rather, what I have done is simply refrained from causing all of the goodness that I could have caused to exist.  The circle is good as far as it goes, but it doesn’t go all the way.

So, in that sense I have only caused what is good.  But wouldn’t it have been better still to cause the rest of the circle to exist?  All things being equal, it would have been, but suppose that the reason I refrained from completing it is that I judged that doing so was necessary in order to explain to my audience the notion of a privation.  Then there would be an overall good situation – the generation of philosophical understanding in my audience – that was brought about in part precisely by my refraining from putting into the circle all the goodness that could have been in it.  The defective circle, though bad, was an essential part of some larger good.  And that is why I willed to refrain from completing it, rather than willing the defect in the circle for its own sake.

Now, . . . the instances of evil suffered that we find in the natural order of things [are thought by some to be] analogous to that.  When a lamb is eaten by a lion, the damage to the lamb amounts to a set of privations – for example, the absence of a limb, flesh, or skin that is torn away.  Though bad considered in itself, the damage also plays a necessary part of a larger good, namely the flourishing of the lion.  Lions of their nature can’t be the kinds of things they are without hunting prey like lambs, so that having the good of there being lions presupposes the bad of lambs being killed.  In causing a world in which lambs are eaten by lions, then, God does not cause evil as such.  Rather, he causes a world in which certain goods (namely the good of lambs having all their limbs, flesh, etc. unmolested) are absent, and these privations are not willed by him for their own sake, but rather as a concomitant of the good of there being lions in existence.