https://www.kmjn.org/notes/message_existence.html

This message does not exist

It can only be discarded

[message_ex]
I received an intriguing notification in the Microsoft Outlook 365
web interface:

    This message can't be saved because it no longer exists. It can
    only be discarded. Make sure you copy the contents of the message
    before you discard if you want to use them later.

I have some ontological questions.

* * *

This message can't be saved because it no longer exists.

Sensible enough. Only messages that exist can be saved; an inexistent
message cannot be saved. But what about that indexical, this? This
message does not exist. Huh.

* * *

It can only be discarded.

We soon learn that we can do more than refer to a message that does
not exist: we may also discard it. A message must exist to be saved;
but it may be discarded without such a constraint. In fact this is
the only thing we may do with it; it can only be discarded.

Perhaps this can be justified. Let's treat discard as the action of
making an object cease to exist. Applying that action to an object
that already does not exist can be considered a no-op. By contrast,
any other action (save, say) requires the object to exist.

* * *

Make sure you copy the contents of the message before you discard if
you want to use them later.

We learn a final affordance, which complicates the story. An
inexistent message has contents, which may be copied - but only if
the message has not yet been discarded.

This is troubling for our hypothesis that discarding an inexistent
message is a no-op. A no-op from the perspective of its existence,
perhaps - the message does not exist either before or after - but
not, apparently, from the perspective of its contents. Undiscarded
inexistent messages have contents that may be copied, while discarded
inexistent messages do not.

The act of discarding a message that does not exist must therefore do
one of two things. It may cause the message contents to also cease to
exist. Alternately, it might not affect the existence but only the
accessibility of message contents. Perhaps they continue to exist,
but discarding the message (which already did not exist) causes the
copy operation to cease being invokable on the message contents (even
though they do continue to exist). The story of existence has many
mysteries.
Mark J. Nelson, 2024-02-13.
Comments welcome: mjn@anadrome.org
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