Please distinguish proof and evidence.
> Not all that counts can be counted.
How do you know that?
> However, he claims we naturally do so all the time, our moral and political ideas being obvious examples.
Yeah, and so incredibly successful, too, how people believe that black people are inferior or homosexuality is an abomination, without any interest in objective evidence.
> When you believe that your mother loves you or in the sincerity of your best friend, you have no conclusively objective evidence.
Yeah, it's absolutely impossible to know whether your mother or your best friend is objectively treating you well or terribly, so what can you do? You just have to assume that they love you!
> In addition, you will never be able to secure such evidence.
WTF? Next you tell me it's absolutely impossible to know whether animals are aggressive and you will never be able to secure evidence?
> Yet it often seems unreasonable to refuse to commit to believing such matters; if we did so, the pragmatic consequences would be a more impoverished social life.
WTF?! Yeah, believing and acting as if someone loves you without any evidence is so socially enriching there is even a term for it: It's called stalking.