Quoting John Cowan <[log in to unmask]>:

> Andreas Johansson scripsit:
> > I would make make a three-way distinction between to believe in
> > something, to disbelieve in something, and to have no certain
> > opinion on the matter. "To doubt something" could be used for the
> > third alternative, but might perhaps better not, since it's usage in
> > not-technical speech tend to suggest being closer to disbelief.
> To take a simple concrete example:
> I believe that (either there is life on Jupiter or there isn't);
> it is false that I believe there is life on Jupiter;
> it is false that I believe there is no life on Jupiter.
> I don't think this can reasonably be called either doubt or disbelief;
> rather it is simply a condition of having no opinion whatsoever.

If we are to use 'to doubt' for my "third alternative", this would indeed be a
case of doubt - you doubt there is life on Jupiter. As I said, the word's
normal usage makes this rather unhelpful, however.

> > "To not doubt something", in normal speech, does indeed mean to believe
> it,
> > illogical as that may be.
> The participants in this debate should go and learn a loglang forthwith;
> then they may still not understand what is meant, but there will be no
> doubt about what is said.

You have a point ...