Abstract.--The strategy theologians apply to their principal subject is not properly available to the writer of SF. The mystery of the Alien, unlike that of God, cannot be preserved by resorting to dogmatically imposed contradictions without betraying the true nature of science fiction. Yet presenting the Alien has its problems. H. G. Wells's approach in making his Martians physically hideous left them mentally and socially unreconstructed; their motives for invading Earth remain recognizable caricatures of human thinking and hence compromise their Otherness. However, the legion of imitators who have debased the example of The War of the Worlds in trying to outdo it in the realm of monstrosity have deposed of that problem by neglecting to furnish their Cosmic Invaders with any motive whatever only to supply themselves with another, by substituting a malign, inverted fairy-tale universe for the real world that SF should model itself after.
The best way out of such difficulties lies with the method the Strugatskys adopt in Roadside Picnic: of not-depicting the Alien. They never allow us a sight of the Visitors, only the concrete results of their "landing." About the latter the authors offer us plenty of details, which viewed microscopically, as it were, remain exactly that: details. Concerning the source and significance of the deadly objects that have constituted themselves as Harmont's Zone there is no end of theorizing; but the explanation finally favored Dr. Pilman's, is the one the title anticipates: that we are dealing with the debris from an Alien roadside picnic.
Within the context of such a hypothesis, the Strugatskys' focus on the lives of the "stalkers," who make perilous forays into the Zone in pursuit of profit, seems designed to discredit both sides in the meeting of two civilizations. The human beings behave solely in base and self-destructive ways, while the Visitors prove their murderous indifference to humanity. Unfortunately, however, the fiction does not exclude a possibility that undermines this intended meaning: that the objects were contained in a space-probe vehicle which broke apart upon nearing our planet; that consequently raining down on Earth, they arrived in damaged condition. This accident would account in the most economical way for all the "fictifacts, " but it does not comport with the authors' title analogy.
If their oversight in failing to rule out the hypothesis of a "damaged gift" is one defect of Roadside Picnic, the Strugatskys' manner of concluding their narrative is another. With Arthur and Redrick's quest for the Golden Ball, the fiction becomes fairy-tale-like--an unintended effect at odds with the book's overall impression. That so highly commendable an attempt to treat the theme of Cosmic Invasion should suffer from these weaknesses underscores the difficulties to be encountered in trying to carry out the optimal strategy of preserving the SF mystery through the very unfolding and presentation of the fictional events.http://www.depauw.edu/sfs/abstracts/a31.htm#c31