Is Jim not taking people seriously or is he not prepared to take what
they
are presenting seriously if they cannot back it up. Big difference with

respect to the intention on Jim's part, ie, **I cannot take you
seriously**
or **I cannot take that seriously**

I thought of exactly that theoretical distinction and pondered it for a
while, but in practice I don't think it makes much difference. "What
you say isn't worth taking seriously" is surely going to be taken as a
personal comment when the poster was clearly speaking with serious
intent.

Let's be a bit more obvious - let's turn it round then. Let me say to
Jim
"Alas, Jim, once again you continue to misunderstand me, and I leave it
to others to decide whether your persistent requests for scientific
evidence - where it is inappropriate or cannot be provided - are worth
taking seriously or not"

How does this sound to you -
a) dismissive
b) friendly