How did Heidegger argue for the certainty of death?

Question

How did Heidegger argue for the certainty of death?

I gather that's a component of one characteristic of death, that it's "not to be outstripped". The other component being its indefiniteness, that I don't know when I will die.

I'm not very sympathetic to either claim taken completely literally. While it's not impossible that I'm about to have a massive heart attack (I've just had it checked out etc.) it seems so improbable that I'll die before I finish this question, that it's not very different to saying that my house is about to fall down, and making that some important practical principle. Likewise, it's not obvious that all people certainty die (which cannot be experienced) rather than demise, else most or all religions would be trivially vacuous.

Are these two components of its not being outstripped meant as emotional appeals, or can they really be made sense of, either as non-literal expressions or statements of doubt (in the possibility of an after-life, that I could have died)?

I would often agree that death cannot be actualized, is always not yet, but not because it is certain and indefinite, only because it can't be experienced by who dies.

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It is called certain in the sense of "being certain as a kind of being of Dasein". This is the "primordial" sense of certainty. Inauthenticity is it also "certain" of death, but it covers up the "thrownness" (p245 SUNY Press) into death.

Because "thrownness" is how the world matters to me, perhaps he just means that death is "certain" in that it matters (to "hold" it for true) that I will die. Is that how he argues for it? Or does "death" mean something else other than the termination of experience?

Answer 1

I would often agree that death cannot be actualized, is always not yet, but not because it is certain and indefinite, only because it can't be experienced by who dies.

In a sense, you are not all that far off from Heidegger's position here.

To my knowledge, Heidegger never argues for the certainty of death, but he also never asserts it. I don't find anything in Heidegger that would burden him with proving in your empirical sense that anything like "Every biological instance of a human being will die." To the contrary, Heidegger (1) tends to characterize death precisely as a possibility; and (2) uses the term 'death' as a technical ontological term.

With reference to point (1), when he characterizes death as "not to be outstripped he says: "Death is something that stands before us---something impending" (250). Death is a certain possibility. This is not the same thing as asserting that death is certain. As a result, there's argument to be made that death is the least certain of all, since it is always something that can only be intended as something-yet-to-come; it can never be present.

For point (2): Death here is thus a technical notion, a term of art. Since it is the always impending possibility of Dasein's impossibility, it acts as a limiting principle, i.e., limiting the possible field of disclosedness of Dasein's being. My own death looms over me as an impending possibility; but I can never encounter it in the way that I can have a meeting looming over me as a possibility, attend the meeting, and be done with it. Thus, any possible encounter with death (such as attending a funeral) is not "Death" in this technical sense. Death is not something we can encounter; it repesents the limit of all possibility of disclosedness.

Thus death as certain possibility is a kind of conceptual notion for Heidegger. It is used here as an ontological, and not a biological notion. It reveals the temporal structure of human existence in Division Two of Being and Time. But as far as I know the assertion that "Death is certain" in the sense of "Two things in life are certain: death and taxes" is not found in Heidegger. For example, I don't think that the discovery of an immortality formula for human beings would change the essential structure of existence as being-toward-death.