The existence of physical evil in nature has posed a difficult problem to many people: how can it be compatible with a Creator who is infinitely powerful and good? We will consider this issue focusing on two main points:
1. what creatures can be the passive subjects of physical evil, i.e. suffer it, and
2. what events affecting those creatures can be designated as physical evil.
Regarding point 1, it is evident that the concept of physical evil refers necessarily to living creatures. The explosion of a supernova that does not affect any life-bearing planet does not constitute physical evil. And moreover, such explosions along the history of the universe were essential for the production of adequate quantities of the heavier chemical elements that are necessary for life. Similarly, a volcanic eruption or an earthquake before there was life on Earth did not constitute physical evil. And moreover, those phenomena are consequences of plate tectonics, which was vital for the existence of life on Earth.
Now, once life appeared and started to evolve on Earth, at what point could the deaths or injuries of living organisms caused by e.g. a volcanic eruption start to be considered physical evil?
- Clearly deaths or injuries of bacteria, archaea, protists, plants or fungi do not qualify as evil, since those organisms cannot possibly experience suffering because they do not have a nervous system. Thus we are left with animals except porifera (sponges) and placozoa.
- And as a simple decentralized nervous system such as that of Ctenophora (comb jellies) and Cnidaria (anemones, corals, jellyfish) works in a basic reactive fashion and cannot experience real suffering, we are left with animals with a central nervous system.
- And as a complex brain is necessary to experience true suffering, we are left in principle with arthropods (insects, crustaceans, arachnids), molluscs and vertebrates as the potential passive subjects of physical evil. We will stop here for now, and will group them together under the term "higher level animals".
Regarding point 2, physical evil would consist of suffering experienced by such higher animals, with suffering leading to death possibly the most extreme case. At this point it is useful to analyze separately some of the causes of death and its associated suffering:
1. old age
2. natural disaster (e.g. volcanic eruption)
3. attack by predator
Notably, if death by old age were considered physical evil, then a world without physical evil would have some very curious properties, as higher level animals would be immortal. First, once the individuals of a particular species have reached a certain number, they should stop reproducing. (Otherwise, since higher level animals would not die from any cause, there would not be enough physical room on the planet for them.) But once they stop reproducing, they would stop evolving. Therefore a world without physical evil where death by old age is considered physical evil would be incompatible with creation of living creatures by evolution. One way to surmount this difficulty would be to define that, for animals (*), death by old age is not physical evil and that only deaths where the subject does not reach its lifespan potential are (i.e. cases 2, 3 and 4 in the list above).
Consideration of natural disasters leads to a curious consequence as well: unless higher level animals were intelligent enough to distance themselves from volcanoes, in order to avoid physical evil plate tectonics should have stopped once those animals appeared. So what's the cause of physical evil in this case: the fact that plate tectonics remained active after higher animals appeared (clearly not) or the fact that animals were not intelligent enough to distance themselves from volcanoes?
But it is the case of starvation whose analysis can provide the most insight. Not an abstract case, but the specific case of St Matthew Island in the Bering Sea in Alaska. In 1944, 29 reindeer were introduced to the island, which was covered with a thick mat of lichens at that time. With the abundance of high quality forage, the reindeer population increased rapidly due to a high birth rate and low mortality (no predators), rising to 1300 animals in 1957 and to 6,000 by the summer of 1963. By 1963 lichen, normally the most important winter forage, had been almost completely depleted by overgrazing, and sedges and grasses were expanding into the sites previously occupied by lichens. The increasing difficulty in obtaining adequate food was evident in the fact that the 1963 reindeer were considerably smaller in both body mass and skeletal proportions than the 1957 animals: in 1963 average body weights had decreased from 1957 by 38 % for adult females and 43 % for adult males. With the reindeer population on an already poor physical condition as a result of competition for high quality summer forage during the summer of 1963, deep snow accumulation during the winter of 1963-64 further restricted the availability of the already depleted winter forage, and almost the entire reindeer population died of starvation, with only 42 animals surviving.
In this case, was physical evil caused by the fact that lichen did not grow fast enough to compensate for the grazing rate? Clearly not, because if lichen had grown at twice its actual rate, the reindeer population would have just reached a maximum of 12000 in 1966 and crashed the next harsh winter. So doubling the rate of growth of lichen would just double the total amount of suffering. Rather, the cause of starvation was just the fact that the reindeer were not intelligent enough to realize that the island had a finite carrying capacity (i.e. could sustainably support a finite reindeer population) and that they should stabilize their population once it reached that carrying capacity. Instead, they were acting like yeast in culture media in a Petri dish, which keep doubling their population until the nutrient is exhausted and then die off. But while death of yeast is not evil because they do not experience suffering, death of reindeer is. Or is it not?
And lastly we have the attacks by predators. Notably, the absence of predators in Matthew Island was one of the factors leading to the population explosion and dieoff. But isn't one kind of death worse than the other? Wouldn't the violence involved in death by predators make it a worse fate than an apparently peaceful death by starvation? Not according to the book of Lamentations, at least: "Better for those who perish by the sword than for those who die of hunger, who waste away, as though pierced through, lacking the fruits of the field!" (Lam 4:9)
We thus come back to our successive restriction of the animals that can be the passive subjects of physical evil. Why stopping at a complex brain and consider physical evil the death of an insect? Why not demanding that the brain must have neocortex, which restricts the selection to mammals? Why not demanding that the neocortex must feature a large frontal lobe, which further restricts the selection to the great apes and humans? Or in functional terms, why not demanding that the animals must be self-aware, i.e. able to pass the mirror test, which would add dolphins and elephants to the last list? And why not just demanding that the brain be developed enough to support the operations of a spiritual soul, leaving just us humans? Why indeed not starting from that point, demanding that, for physical evil to be tragic, its passive subject must be a person with a spiritual soul?
In our view the last is the only correct approach, as any other threshold to define physical evil is arbitrary. Thus, we posit that physical evil exists in two fundamentally different kinds: non-tragic when it affects animals and tragic when it affects humans. Non-tragic physical evil is part of God's design in creation, and exists in view of the overall greater good of the material cosmos. In contrast, tragic physical evil was not part of the original design in creation, as man was originally "shielded" from the physical evil that would have affected him otherwise as a result of its biological nature: as long as man remained in the divine intimacy, he would not have to suffer or die (Gen 2:17; 3:16, 19). It was as a result of original sin that man lost that privilege ("preternatural gift") and became subject to physical evil just as animals are. With this approach, there is no problem whatsoever harmonizing physical evil with the existence of an all-powerful, infinitely good Creator.
(*) In contrast to the case of animals, for humans the preternatural gift of bodily immortality would not necessarily have implied that at some point in time they would have had to stop reproducing, because bodily immortality did not imply that each person would have stayed alive on Earth until the end of times. Along the line of 1 Cor 15:51 "We shall not all fall asleep, but we will all be changed," it is legitimate to assume that, if man had not sinned, after a certain number of years (120, 365, 969, whatever), the body of each person would have been glorified without dying and that person would have been taken up body and soul into heavenly glory, to enjoy the Beatific Vision.