Murine Metaphysics

Higher life forms are generally regarded as possessing qualities and characteristics that transcend the particular genetic material of which they are composed. A person whose genetic make-up is modified by radiation does not cease to be him or herself. Likewise, the same mouse would exist absent the injection of the oncogene into the fertilized egg cell; it simply would not be predisposed to cancer. The fact that it has this predisposition to cancer that makes it valuable to humans does not mean that the mouse, along with other animal life forms, can be defined solely with reference to the genetic matter of which it is composed…

In Harvard College v Canada (2002 SCC76), Bastarache J blithely disposes of the problem of personal identity, one of the oldest and most contentious issues in philosophy. 

Primus was born a tiny helpless baby. Fifty years later, he is six feet tall; every cell in his body has been replaced multiple times; he lost both his hands (and fingerprints) in a tragic accident; all his teeth have been removed and replaced with dentures; he has undergone CRISPR gene therapy for hereditary hemophilia. He has no memory of being a baby and would not recognize himself or his childhood crib in a photo. What makes little Primus and big Primus the same individual?

Medieval Indian philosopher Nagarjuna approached this problem with the doctrine of two truths – one ultimate, one conventional. Ultimately, in the metaphysical sense, little Primus and big Primus are not the same individual. Try as we may to find some enduring, essential quality or characteristic through which to identify them, we will never find it. Any enduring identity we ascribe to them is purely illusory. The same is true of all individuals – even from one day to the next.

Conventionally, however, it is useful to think of human individuals as having essential identity. Primus’s father died when he was still a baby, and in his will, he gave a life interest in the family home to his wife, with full ownership rights reverting to Primus upon her death. The executor of the mother’s estate may not argue, “but you aren’t Primus. The Primus to whom the home was bequeathed weighs eight pounds, and he has two hands, and he has the gene for hemophilia.” We organize human affairs as if human individuals “really existed” in an enduring sense, because for our mundane purposes, they do. “Primus” as an enduring, identifiable individual is basically a legal fiction, but like all legal fictions, we must behave as though it is reality.

The law can only operate on the mundane plane. Only the conventional, not the metaphysical, may be considered in judicial reasoning. It is not for the courts to decide the ancient philosophical issue of atman or anatman, especially when millennia of philosophers have failed to form a consensus. Binnie J is correct: it is not appropriate for the courts to take judicial notice of metaphysical theories.

I cannot think how to interpret Bastarache’s reasoning in a purely mundane or conventional way, and I have tried. What does he mean when he says, “the same mouse would exist absent the injection of the oncogene”? Which mouse? Does the notion “the mouse which does not now exist, but in the future will exist, whether genetically modified or not” have a meaningful referent? With which transcendental “qualities and characteristics” could that mouse be identified? Could the oncomouse be patentable if it were also genetically modified to have only a brainstem and completely lack cognition and subjective awareness?

Metaphysically or “ultimately”, Bastarache’s reasoning bristles with contentious problems. Conventionally, it is meaningless.