Death, according to Martin Heidegger, was a fundamental fact about human existence. Life was movement through time toward an end.

Birth, for Heidegger’s critical ex-student Hannah Arendt, was the fundamental fact about human beings as moral or political creatures. At birth, our life course is maximally open, unpredictable, and, in that sense, free. Birth or “natality” symbolizes our power to start anew.*

Rebirth, for the man we call the Buddha, was the fundamental fact about life. At least according to one tradition, he did not mean a literal transfer of the soul into a different body at death. When one of his monks taught that doctrine, the Buddha apparently rebuked him, saying, “From whom have you heard, you foolish man …, that I have explained the dharma in that way? Foolish man, have I not declared in many ways that consciousness is dependently arisen …?”**

What then did he mean? Here is a sympathetic reconstruction:

1. I cannot directly perceive my self or its effects. All I perceive is a sequence of sensations, judgments, desires, and other ideas. The Buddha is a strict empiricist. If we cannot perceive something by any means, it is nothing. As David Hume wrote, I am “nothing but a bundle or collection of different perceptions, which succeed each other with an inconceivable rapidity, and are in a perpetual flux and movement.”
2. Each of these ideas has a cause. It does not arise from nothing but depends on something before it. We might identity the causes of ideas as other ideas or as physical processes in the brain. That is merely a difference in the level of analysis. Either way, the core premise is “dependent origination” (pratityasamutpada). Every idea is part of a long causal chain.
3. My ideas do not have the same span as my life. When I was one day old, I had none of the ideas that now fill my brain. Many of the ideas that I had when I was 5 or 15 are forgotten, although their indirect effects may linger. Some of the ideas in my mind today were in my father’s head before I was born. I will forget some of my ideas while they still are alive in other minds.
4. I was not born free, in the sense of having a self capable of choosing its beliefs and desires. I was born as a thinking organism which learned its beliefs and desires from experience, strongly shaped by the already-living people around me. As Karl Mannheim wrote in 1928, “even if the rest of one’s life consisted in one long process of negation and destruction of the natural world view acquired in youth, the determining influence of these early impressions would still be predominant.”
5. My thoughts may have consequences (“karma”) for others, going beyond my lifespan. Even if you sharply disagree with me, by sharing my idea with you, I have affected you.
6. If the self is a bundle of constantly changing ideas that are caused by other people’s ideas and shared in part with other people, then the moment of my biological birth was not the beginning of “me,” nor will my biological death be the end. The bundle that is me is constantly being reborn, in my consciousness and in other minds.
7. Notwithstanding 6, different minds are not the same. I am not you. Individuality is real, in some sense, and biological death matters.
8. Notwithstanding 2, the sensation we have of choosing and controlling our ideas is valid (morally, if not metaphysically).

Rebirth captures this combination. A birth is a new beginning but not ex nihilo. It is wonderful but not literally miraculous, being the result of regular natural processes.  It marks a break with a past, yet the newborn is completely dependent on and thoroughly influenced by adults. We might view rebirth as a metaphor for life, but if one thinks (with the Buddha and Hume) that the “self” is fictional or metaphorical, then what is metaphorical is the assertion that life begins in infancy. Literally, life is continuous renewal, and that makes rebirth more literal than birth.

*This paper argues that the contrast between Heidegger and Arendt on birth/death is overblown.
**Quoted in Pankaj Mishra, An End to Suffering: The Buddha in the World.