The case against cryonics

What is striking about cryonics is that those who have taken serious efforts to understand the arguments in favor of its technical feasibility generally endorse the idea. Those who have not made cryonics arrangements usually give non-technical arguments (anxiety about the future, loss of family and friends, etc), lack funding or life insurance, or are (self-identified) procrastinators. In contrast, those who reject cryonics are almost invariably uninformed. They do not understand what happens to cells when they freeze, they are not aware of vitrification (solidification without ice formation), they think that brain cells “disappear” five minutes after cardiac arrest, they demand proof of suspended animation as a condition for endorsing cryonics, etc.

This does not mean that no serious arguments could be presented. I can see two major technical arguments that could be made against cryonics:

1. Memory and identity are encoded in such a fragile and delicate manner that cerebral ischemia, ice formation or cryoprotectant toxicity irreversibly destroy it. Considering our limited understanding of the nature of consciousness, and the biochemical and molecular basis of memory, this cannot be ruled out. Cryonics advocates can respond to such a challenge by producing an argument that pairs our current understanding of the neuroanatomical basis of identity and memory to a cryobiological argument in order to argue that existing cryonics procedures are expected to preserve it. An excellent, knowledgeable, response of this kind is offered in Mike Darwin’s Does Personal Identity Survive Cryopreservation? Cryonics skeptics in turn could produce evidence that existing cryonics procedures fall short of this goal.

2. The cell repair technologies that are required for cryonics are not technically feasible. This argument should be presented with care and rigor because the general argument that cell repair technologies as such are not possible contradicts existing biology. A distinct difference from the first argument is that it is harder, if not impossible, to use existing empirical evidence to settle this issue. After all, making cryonics arrangements is a form of decision making under uncertainty and such decisions are not straightforwardly “correct” or “incorrect,” “right” or “wrong.” What can be done is to provide a detailed scientific exposition of the nature and scope of the the kind of repairs that are necessary for meaningful resuscitation and to argue that both biological and mechanical cell repair technologies are not conceivable – or are conceivable.

One thing that becomes immediately clear from this exercise is that there is no single answer to the question of whether cryonics can work because the answer to this question depends on the conditions and technologies that prevail during the cryopreservation of a patient. This introduces a set of more subtle distinctions concerning the question of what kind of cryonics should be assessed. It also produces an argument in favor of continuous improvement of cryonics technologies, and standby and stabilization services.

This short examination of technical arguments that could be made against cryonics gives advocates of the practice two talking points in discussion with skeptics or hostile critics:

(a) If a critic flat-out denies that cryonics is technically feasible, it is not unreasonable to ask him/her to be specific about what (s)he means by cryonics. This simple question often will reveal a poor understanding of existing cryonics technologies and procedures.

(b) A decision made on the basis of incomplete knowledge cannot be “right” or “wrong” and should be respected as one’s best efforts to deal with uncertainty.

The case for cryonics

The biology-of-aging blog Ouroboros has posted a skeptical post about cryonics that is highly representative of how most biological scientists respond to questions about cryonics. The discussion of cryonics is largely reduced to a discussion of the technical feasibility of suspended animation and resuscitation requirements. But suspended animation is not cryonics. Cryonics should be discussed in the broader context of decision making under uncertainty. People who have made cryonics arrangements are more than aware that contemporary science is not able to vitrify and resuscitate a complex organism. To them the central question is whether we can reasonably expect that future technologies will be able to repair the injury that is produced by contemporary cryopreservation technologies and rejuvenate the patient. That is the “probabilistic” side of the issue. On the utility side of the equation is nothing less than personal survival.

This does not mean that cryonics should be approached as a form of Pascal’s Wager in a vacuum. Experimental evidence from fields such as cryobiology, biogerontology and nanotechnology plays an important role in shaping our expectations about the technical feasibility of the resuscitation of cryonics patients. Many biologists, however, feel confident that they can make a case against cryonics without even bothering to examine the current state of the field. For example, how many biologists know that the latest generation of vitrification agents have low enough toxicity to permit vitrification of animal brain slices with retention of electrical activity?

The author writes:

The field could take a lesson from the dawn of modern biogerontology back in the early 1990s: Acknowledge the mind-bending complexity of the challenge. Create model systems for cryonics, using the best tools from the vast edifice of modern biological knowledge.

But that is exactly what the cryonics field has done. Millions of dollars have been devoted to identify low-toxicity vitrification agents and protocols to preserve viability after pronouncement of legal death.  Progress in the cryopreservation of complex organs (including the brain) has been so successful that the vitrification agent that is currently used by the Alcor Life Extension Foundation, 21st Century Medicine’s M22, is the least toxic vitrification agent in the peer reviewed cryobiology literature to date.

The author is correct that the project of cryonics is of “mind-bending complexity.” One major reason for this is that the resuscitation of most cryonics patients will require successful rejuvenation. As a result, cryonics advocates are quite interested in anti-aging research. But whereas modern biogerontology, not unlike macroeconomics, is still plagued by ongoing (technical) debates about even the most basic definitions employed in the field, or engaged in discussions about what constitutes the most effective approach to pursue rejuvenation, the cryonics field has moved from the practice of the crude freezing of patients to the pursuit of long term care at cryogenic temperatures without ice formation and minimal ischemic injury.

Perhaps there is good reason for this difference in success rate. As mathematician and cryonics advocate Thomas Donaldson pointed out, anti-aging research faces conceptual and methodological challenges that cryobiology research does not. Perhaps the time scale to develop and validate effective anti-aging strategies is similar to that of developing a mature technology that can manipulate matter at the molecular level. If this is the case, rejuvenation research could benefit from being pursued as a broader evolutionary bio-nanotechnology research program.

The discussion of cryonics is most fruitful where logic and empirical science meet.  We need to employ the tools of logic to guide coherent decision making and we need the results of experimental science to provide empirical weight to guide those decisions. In a world where knowledge is recognized as probabilistic, and where death is recognized as a biological process that can be halted through the use of low temperatures, the decision to make cryonics arrangements can be rational and life-affirming.