In a posthumously published essay entitled “Theism,” the great 19th century British philosopher John Stuart Mill takes an agnostic stance on life after death. Here I will review some of Mill’s arguments in this essay.
Mill rehearses the standard “correlation argument” against survival (formerly deployed by Lucretius, Hume and others). He observes that “the different degrees of complication of the nervous and cerebral organization, correspond to differences in the development of the mental faculties; and . . . diseases of the brain disturb the mental functions and . . . decay or weakness of the brain enfeebles them. We have therefore sufficient evidence that cerebral action is, if not the cause, at least . . . a condition sine qua non of mental operations.” Mill rightly concedes, 
however, “these considerations only amount to defect of evidence; they afford no positive argument against immortality.”
Mill further notes that belief in immortality isn’t grounded in philosophical or scientific arguments anyway but rather is inspired by “our own wishes and the general assent of other people.” There is also the fact that immortality is naturally desired, which some (such as Aquinas) have parleyed into an argument in favor of the belief. Mill writes, “We are told that the desire of immortality is one of our instincts, and that there is no instinct which has not corresponding to it a real object fitted to satisfy it.” Mill critiques this argument by comparing it to an inference from the desire for food to the conclusion that we will always have plenty to eat. This is clearly a misunderstanding of the argument, however. Since the inference is not just from the presence of desire to the conclusion that the desire will be fulfilled. Rather, the argument reasons from the fact that there is a natural human desire to the conclusion that that desire can be fulfilled (not that it necessarily will be). So Mill’s criticism doubly misconstrues the argument from desire.
Mill notes another line of argument, which is based in the goodness of God and “the improbability that God would ordain the annihilation of his noblest and richest work . . . and the special improbability that he would have implanted in us an instinctive desire of eternal life and doomed that desire to complete disappointment.” He says the problem with this argument is that it assumes we know more than we do about God’s broader purposes, some element of which might have made it best to give us this desire without its being fulfilled. Mill is certainly correct on this point.
Mill concludes that we have “no assurance whatever of a life after death on grounds of natural religion. But . . . there is no hindrance to his indulging that hope.” This tempered conclusion makes sense given the arguments he discusses, even despite his misconstrual of the argument from desire. Philosophical arguments (or those based on “natural religion,” as he puts it) for life after death, much less human immortality, are probably fall short of providing anything like assurance, at least those arguments available in Mill’s day. (Contemporary arguments based on recent near-death experience research, however, might be a different story. I will explore such in some upcoming posts.) But Mill is also wise to allow for the reasonableness of indulging in the “hope” of life after death. I would certainly say so, given (1) the nearly universal desire for survival, (2) the Kantian point that ethics depends upon immortality, and (3) the theological grounds for immortality, which are considerable.
