Hi all,

I think that the whole discussion on "available" and "valid" is based on
different interpretations of those words, and the use in a different
context. Valid is being used both connected to the nouns "species" and
"name".
A name is not the same as a species. Therefore we must first find out what
valid is really, and not what we think it might be.

So let's have a look at the glossary of the code, which defines the word
valid:
Valid, a. (validity, n.). Of an available name or a nomenclatural act: one
that is acceptable under the provisions of the Code and, in the case of a
name, which is the correct name of a taxon in an author's taxonomic
judgement. (Code p. 121).

The rest is in fact plain and simple: A valid name for a taxon has to be:
1) available [that is meeting the requirements of the code]
2) the correct name of a taxon, which, in most cases, follows the rules of
priority [see for exceptions to this strict priority rule earlier
contributions to this discussion]. Junior synonyms, are therefore not valid
names, unless at a certain point a taxonomist "decides" that a junior
subjective synonym (an objective synonym will always remain a synonym as it
is based on the same holotype specimen) actually represents another species.
In that case, the first available junior synonym (which at that point is no
longer a synonym) becomes the valid name for the new species.

Gijs C. Kronenberg