The third Rationalist principle of Medical Halacha is the Mixed Up Medical Principle. The importance and relevance of any legal system can be measured by how the system can be applied to rapidly changing situations. However, the difference between the halacha and the various secular legal codes is that, at least in theory, the halacha was meant to last forever, i.e. the ground rules were never meant to change. However, in a secular system, there is usually some mechanism by which the rules can change. So if the people of the United States for example decide that they don't like certain rules, there is a mechanism to change the rules. If a new situation arises, new rules can be devised to apply to the new situations.
However, in halacha, the rules are divinely directed. Therefore, the rules cannot change, and in general, we cannot make up new sets of rules. So the interesting part of the halachic process is figuring out how to apply the same old rules to new situations that arise throughout history. This makes it extremely important to figure out what the original rules actually were, so that we can apply them correctly to new situations.
Let us now analyze some modern situations according to the major group of poskim, the cardiovascular death advocates (CDA). According to the CDA, the chazal defined the time of death as the cessation of spontaneous respiration. In actuality, what the gemara said was that you can declare death based on the fact that the victim buried in the rubble was not breathing on his own. The CDA believe that we can derive from here that anyone who has stopped breathing on his own (and since according to the gemara breathing and the heartbeat are connected - he also has no heartbeat - see the Chacham Tzvi as mentioned in previous posts) is halachically dead, and the converse as well, that anyone who still has a heart beat or is breathing is halachically alive.
When we try to apply this rule to modern situations, this way of learning the gemara leads to several absurdities. Anyone involved in modern day search and rescue knows that when you discover a victim at the scene of an accident, even if he is not breathing and/or his heart is not beating the first thing you need to try is CPR. Only after this fails can you declare him/her dead. In applying the rules of the gemara according to the CDA, there would be no obligation to perform CPR!
Another similar scenario would be the person on a "heart-lung" machine (usually used in cardiac surgery - the blood is diverted from the heart and lungs during surgery and it acts as a temporary heart and lung while the heart is surgically repaired). In these cases it would seem that the patient is halachically dead!
The CDA poskim (see Rabbi Bleich here - bottom of page 90) do recognize this problem with their interpretation, and they therefore add the condition of "irreversible cessation of spontaneous respiration" i.e. that the gemara only meant to say that he/she is dead IF there is no chance of getting the person to breathe again. But this is clearly something they are reading into the gemara, the gemara could not possibly have meant this.
This is clearly a product of poskim reading into the gemara conditions that are simply not there. There is no question in my mind, that the gemara meant exactly what it said. According to the gemara, if a person is not breathing, you can assume that he is dead. But the CDA have some more difficulties trying to apply this to more modern scenarios. What about the polio patient who can't breathe on his own, but requires an Iron lung? Is he halachically dead? What about the person under anesthesia who requires a respirator to breathe because the medications of anesthesia do not allow him/her to breathe?
Since the CDA take the gemara at face value, they have to make all sorts of twists and turns in order to explain how to apply the principle of cardiorespiratory death to situations that the gemara simply could not have possibly conceived of. So many of the conditions that they make up may sound logical, but they are clearly not what the gemara intended.
So how then are we supposed to apply the halacha to modern situations? Is it impossible? Should we simply throw out the halacha and say that it is irrelevant to modern medicine?
Of course not! We need to do the obvious! The gemara applied its understanding of physiology to teach people in those days how to determine death. The gemara did not know about respirators, iron lungs, and CPR! The gemara thought that life resided in the breath of the nostrils which then gave life to the beating heart. So the gemara said that you have to listen to his breathing, and or feel for the heartbeat to determine if the person is dead.
We on the other hand, should learn from the gemara exactly that same principle! Since we know that the brain directs all of the body's actions including breathing, and we know that consciousness resides in the brain, also know that in order to determine death we need to make sure that brain is no longer functioning in order to determine death! In this way we can be very consistent in the application of halacha. Just as chazal determined death by searching for signs in life where they thought the source of life resided, so should we! If life can be restored by CPR, the we are obligated by halachabecause the brain is where the source of life for the body resides.
In fact, the CDA all agree that CPR would be required if there is a chance to resuscitate someone. They explain this usually by using the irreversible cessation of respiration criteria that we mentioned above. However, they are usually unwilling to use this same criteria the other way around, i.e. if the person's heart and lungs are still breathing/beating they still consider the person alive despite the fact that he will never be able to breathe on his own due to brain death! This, to me, is mixed up.