Let R = “something is believed by someone”; symbolically R =
(Ex)(Ey)B(x, y). Given this, it is plausible to suppose that
the following is true:
(1) It is believed that R; therefore R;
Symbolically: B(a,R) --> (Ex)(Ey)B(x,
y).
In its general form, however, the schema (1) does not
hold. That is, the following is not
semantically valid:
(B) It is believed that P; therefore P
Substitute another proposition in it, and we get something
that is false, for example:
(B1) It is believed that the Earth is flat, therefore the
Earth is flat.
All of this is the case, of course, even if P is believed by
everyone. A universally held belief does not logically
entail the truth of that belief.
The same holds even for very strongly held moral
beliefs. If we let P = “walking on grass
is immoral”, then on this interpretation, (B) is, plausibly, not true.
I get the feeling that a great deal of discourse is diminished because of a failure to notice this. Lines of thinking such as:
“I strongly believe that P, so P”; or
“I really feel that P is right/wrong, so P is right/wrong”
strike me as intellectual vices, not uncommon in, for
example, politics.
It is often thought that in the case of mental states, (B)
holds. For example:
(2) I believe that I am in pain therefore I am in pain;
(3) I believe that I have an experience of bright blue; therefore I have an experience of bright blue;
(4) I believe that I have the experience of a pink
elephant; therefore I have the experience of a pink elephant.
With regard to our mental states, we are often thought to be incorrigible.
I am not sure this is necessarily the case. That is, I don’t see why it is impossible to
be misled about having a particular experience.
Perhaps it is in fact another kind of experience that we immediately
re-interpret as something else, so that we never register that it
was a different kind of experience in the first place. Or, perhaps we now look back on the
experience and realize we were doing some distorting in the
moment, and while at the time we were sure that we had an experience of blue,
we now concede that it was in fact of purple:
(3’) I believed that I had an experience of bright blue, but I didn’t have an experience of bright blue.
But even if you disagree with this, then we can still be
misled about the content of our experiences.
For example:
(5) I believe that I am hearing the President of the United
States speak in the next room; therefore I am hearing the President of the
United States speak in the next room;
(6) I believe that I see someone who is shorter than me;
therefore I see someone who is shorter than me;
(7) I believe that I am having the greatest experience of my
life; therefore I am having the greatest experience of my life.
All of these, I submit, can be false. One might, for example: hear the voice of an
excellent mimic; see someone from an angle that distorts their height; and,
while having a great time, momentarily forget about an even better experience in
the past.
I think that no matter how we look at it, (B) is semantically
invalid.
