There are many people who subscribe to the idea that accurately preserving the fine structure of the brain on death, having that brain scanned and discarded, and the data of that scan later used to run a whole brain emulation is essentially no different from cold water drowning followed by successful resuscitation. There is a stop, and then a start. That the same pattern is running in a completely different system, and the original is destroyed, is immaterial: the pattern is the self. The rest of us would say that this individual died permanently with the destruction of the preserved brain, and the emulation is a copy - and possibly not even a continuous, surviving, single entity, depending on the implementation.
Which of these views you or I hold is entirely unimportant right up to the point at which it is possible to preserve the brain on death and have some choice about what happens next. Since we do presently live in the era of brain preservation by vitrification or, recently, vitrifixation, whether one holds a pattern identity view (the self is the pattern) or a continuity view (the self is the pattern as embodied in this particular set of matter) can turn out to be important. The former will kill you, if you let it steer your choices. Clearly I'm not the only one who feels that pattern identity beliefs have the potential to be dangerous to those who subscribe to them, as illustrated by this article on the options for near future development of improved methods of brain preservation.
As someone who is fully supportive of the ultimate goals of the cryonics enterprise, but still views the current state of the practice with some degree of skepticism, I make a point of acquainting myself with the latest evidence regarding the quality of cryonics procedures and their ability to preserve the foundations of a person's identity through time. Over the past two years or so, I have increasingly seen a recent achievement by 21st-Century Medicine (21CM) cited by some cryonics supporters as demonstrating the scientific validity of those procedures: namely 21CM's research on aldehyde-stabilized cryopreservation (ASC). This new technique has allowed them to win the Technology Prize awarded by the Brain Preservation Foundation (BPF) by demonstrating excellent preservation of brain ultrastructure. Were I to follow this line of reasoning, I could happily set aside my concerns about the adequacy of today's cryopreservation procedures, which had now been verified by scientific experts; the proper focus would now need to be on how to responsibly introduce those procedures into a clinical setting, for patients at the end of their lives who might request them.
It turns out, however, that things are not so simple. ASC is no doubt a step forward for the field of brain banking, and as its name indicates, it it is indeed a form of cryopreservation, since it involves vitrification of the brain at -135°C. Nonetheless, ASC does not count as cryonics, insofar as it uses a fixative solution prior to vitrification and cooling, which could potentially preclude revival of the original biological brain (an essential part of cryonics as traditionally understood). And indeed, biological revival with the help of future technology is not a priority for the Brain Preservation Foundation (BPF)'s president, Dr. Kenneth Hayworth. Rather, he envisages brain preservation as conducive to life extension via mind uploading: a process that would involve cutting the preserved brain into thin slices, scanning each slice, and feeding the resulting data to an advanced computer that would thereby be able to map out the entire network of neural connections in the person's original brain, and ultimately to emulate that person's mind. This is quite different from cryonics.
The BPF's commitment to holding brain preservation research to the highest standards of scientific rigour is laudable, and worth emulating. Nonetheless, for those interested in brain preservation with a view to enabling life extension, supporting cryonics-specific research remains the safer bet. We should not simply rely on the BPF's approach if our goal is to try and save those whom medicine in its current state cannot restore to life and health.
To see why this is so, let us begin by noting the two main philosophical theories of personal identity through time that are relevant when discussing the respective merits of cryonics and mind uploading in this context. The first one, which we can call the "Physical Continuity" (PhyCon) theory, asserts that a person is identical with the physical substratum from which her mind emerges: that is to say, her brain, with its intricate web of neurons and synaptic connections. The second relevant theory can be referred to as the "Psychological Continuity" (PsyCon) theory. Roughly speaking, it says that you are to identical with the set of psychological features (memories, beliefs, desires, personality traits, etc.) that constitutes your mind. On this view, preserving you after you have been pronounced dead requires ensuring the persistence of enough of those psychological features, in an embodied mind of some sort (but one that need not be embodied in your current biological brain).
If that is the case, what is the prudent choice to make for those who wish to promote life extension through brain preservation? I submit that traditional cryonics is the more prudent option to pursue. This can be demonstrated using a simple argument that considers what the implications are if we assume that PhyCon and, respectively, PsyCon are true. Suppose first that PhyCon is true. If so, a cryonics procedure carried out properly will save a person's life, whereas using a technique like ASC that compromises the brain's potential for viability, followed by destructive scanning and uploading, will kill that person. If PsyCon is true, on the other hand, both methods can ensure survival. Indeed, adequate cryonic preservation of a person's brain would also preserve the ultrastructure grounding the various psychological features that defined that person.
None of this is meant to imply that the work of the BPF is without merit. On the contrary, the Foundation's approach demonstrates a number of virtues that can provide a model for the cryonics movement to follow. These include a commitment to rigorously and impartially evaluating the quality of brain preservation procedures, in accordance with the standards of scientific peer-review. Another example is the BPF's successful effort at crowdfunding its incentive prizes for brain preservation research, such as the two prizes won by 21CM.