One of the main takeaways from this discussion, for me, is that while some formal arguments may be valid, they are not necessarily valid in an informal setting.

To wit,

B
Therefore A→B
Formally valid.

Water was added to the lake.
Therefore,
If it is cloudy out, then water was added to the lake.
Informally not valid.

as well as -

A ^ B
Therefore, (A→B).
Formally valid.

Kangaroos are marsupials and Paris is the capital of France.
Therefore,
If kangaroos are marsupials, then Paris is the capital of France.
Informally not valid.

Hawt damn. Looks like it was worth all the posts after all :D