Saturday, November 12, 2005

Gazzaethics I

What does a member of the US President’s Council on Bioethics think about the consequences of brain science? How does is knowledge about the brain influencing bioethical decisions? Michael Gazzaniga is a world-renowned neuroscientist and one of the very founders of modern experimental cognitive neuroscience. He is also a member of the Bioethics Council. In his recent book, The Ethical Brain, Gazzaniga not only presents the new discipline of ‘neuroethics’. He is also putting forth his own views on the vital matters. In many ways, Gazzaniga’s own take on the ethical problems are indeed the most interesting parts of the book, and they will surely be found provocative by a lot of readers.

Although the book is relatively small (178 pages plus endnotes) and written as a popular science book, the issues treated here – and Gazzaniga’s views – are well worth a closer look. Despite that Gazzaniga sometimes takes logical leaps from premise to conclusion, the book is clearly a most accessible and entertaining book. As member of the Bioethics Council, Gazzaniga has an impact not only on US law and ethics, but potentially a worldwide influence on how we think about ourselves and others, about free will, when life begins and ends, and on brain enhancements. So let me start by taking on one part at a time; life-span ethics, brain enhancement, brain and the law, and “universal ethics”

“An egg and a sperm is not a human. A fertilized embryo is not a human – it needs a uterus, and at least six months of gestation and development, growth and neural formation, and cell duplication to become a human.” (p. 11)

Gazzaniga leaves no doubt that there are specific boundaries for what can be called a human and what cannot. A fertilized embryo goes through a series of necessary steps before becoming the complex organism that makes up a human baby. But where along this development do we draw the line of what is human, a being to be given rights as any other human being? Anti-abortionists make use of the “continuity argument” which states that a fertilized egg will go on to become a human being and therefore deserve the rights of an individual. In this view the embryo is a (potential) human being from conception and onwards that should be given rights accordingly. This stands in sharp contrast to today’s practice in many countries worldwide, accepting abortion before the embryonic age of 23 weeks.

In order to make good judgements about these issues, says Gazzaniga, we need to consult scientific evidence. Based on findings from neuroscience, Gazzaniga refers to the development of the brain (and mind). It is now well-know that it is only in weeks 5 to 6 that the first electrical brain activity occurs. However, this activity is much too crude to be called “brain waves”, which is the assembly of neuronal populations working together, and a hallmark of mental life. It is first around week 23 that synapses start to form and lay the ground for coherent assemblies of brain activity. In order to see the relevance of these brain waves we should look at the other end of the life line: brain death. The complete and irreversible cessation of brain activity is the clinical hallmarks of the end of life. This is an uncontroversial fact across countries and religions. Practice on the determination of brain death may vary between countries and regions, but the basic assumption that brain death signifies mental death is considered a well established fact today.

The following concluding argument is obvious: while neural activity can be found in brain dead patients, the incoherent, scattered and unorganized activity found – and signifying death – here corresponds to the activation found in embryonic stages up until around week 23. Before that, the neural activation does not represent any integrated thought or behaviour. The embryo is not a mental being before week 23.

What, then, about the continuity argument? As mentioned, there are those who claim that any fertilized egg will continue to grow into a human, and that because of this a fertilized egg should be given the same rights as you and me or any other human. This argument moves beyond the current state of the embryo, basically stating that the human “soul” is present right at or after the fertilization of the egg. Gazzaniga replies here by addressing what he calls the “potentiality argument”; the view that “since an embryo or fetus could become an adult, it must always be granted equivalent moral status to a postnatal human being” (p. 11). The premise here (always look for the premises!) is the assumption that a fertilized egg will always develop into a human being. However, such a view is based upon an uninformed view of fertilization and embryonic development. During the first fourteen days both twinning and chimeras may occur. That is, the fertilized can become two individuals, or it can split into twin eggs and then move back into one egg again. This is in stark contrast to the continuity argument. Otherwise, we should be talking about splitting souls and chimera souls, right?

Gazzaniga gives us a new perspective on ethics; our moral decisions should now be informed by the best possible available evidence on a subject matter. We should not be led by our gut feelings or implicit assumptions about such complex mechanisms as the growth of a human embryo. In order to make sound decisions, we must consult the evidence.

2 Comments:

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