I have to agree with Tim May, this list was not a good fit for him. So I
am not going to join the chorus of voices appealing for him to return.
There are plenty of forums on the net to discuss all sorts of matters,
and if a list is not a good match for a person, there's no point in
trying to make it otherwise.
As one example of the problem, I'll just point out that his apparent
belief that our philosophical debates amount to a "religion" is
obviously completely mistaken. I'm not sure how he came to that
conclusion. Perhaps he misunderstood the purpose of the list, to
discuss the implications of the various ideas that "everything exists".
Everything we say is implicitly prefaced by the conditional clause,
"If all <whatever>s exist, then".
This is a pretty radical assumption and so it is not surprising that
sometimes it leads to radical results. Some people may be so shocked
or dismayed by the results that they can't look dispassionately at the
reasoning that may (or may not) support them, or remember that they are
based on a very speculative assumption.
The bottom line is that we should not be concerned as people come and go
in their involvement in this list, or any other Internet discussion forum.
The important point is the quality of the discussions and the debate.
Quality attracts quality, and the converse is true as well. If we
start having problems with poorly thought out ideas, the best solution
is to take the time to criticize them (the ideas, not the presenters).
That way we can hope to keep the level of discourse at a high level and
continue to attract good contributions.