This thesis is a tool for evaluating the ethical desirability of considerable life extension. The discussion on the topic brings together metaphysical questions related to life and death as well as practical bioethical concerns related to just distribution, the environment and new technologies. Due to the multifacetedness of the topic, there does not exist a unified ethical discussion on the issue.

Manipulating the biological aging process by means of new medical technology changes the way we look at old age, aging and mortality. Intuitively, people see life as a good thing. Most people think that death is bad and that more life is always better. Yet most people would not want to live forever. This paradox is essential: we do not want to die but we do not want to live forever, either. On the other hand, living for hundreds of years is very different from eternity and thus a considerably long life appeals to many.

Life extension is personally desirable for many but some philosophers argue against life extension based on societal or environmental concerns. My claim is that even though it is not obvious that considerable life extension would be ethically desirable, it is at least ethically acceptable. However, there are also good reasons to remain cautious when developing solutions that could enable a considerably long life by manipulating the process of biological aging.

The first part of the thesis is an introduction to the ethics considerable life extension. The second part consists of reprinted original articles on more specific themes related to the topic.