Re: [ontolog-forum] Foundation Ontology [was Semantic Web shortcomings]
I suggested the term UFO as a joke, but we should recognize that the
problem of symbol grounding is significant. And we should note that
there are three methods of grounding the symbols we use:
1. Direct experience with the referents by perception and action.
2. Indirect connections to experience by associations created by
patterns of words that are more directly grounded.
3. Communication by means of natural languages with other people
whose grounding for the symbols is more direct than ours.
The issue of grounding the symbols used in AI was a hot topic
back in the 1980s with lots of spilled ink about Searle's
Chinese room. The people who are working on robots are finally
answering the symbol grounding questions by connecting symbols
to the robots' systems of perception and action.
In any case, I was never really worried about symbol grounding
because people have been using ungrounded books for millennia.
Some books link the words to pictures, but the main method for
grounding words is to take advantage of the human methods of
communication (point #3 above).
For example, very few of us have any direct experience with the
experiments that established the existence of atoms and bacteria,
but we use those words all the time. We also have no direct
knowledge of things inside our own bodies, such as bones, heart,
liver, brain, etc. But we accept the information that people
who have more direct experience with such things have told us.
We can also talk about cities and countries we have never visited.
When we actually go there, we discover new things we hadn't expected,
but we also find that our most important expectations are fulfilled:
there are people at those locations who can provide food and shelter
and the means for us to get back home again.
Therefore, I consider symbol grounding a solved, or at least solvable
problem. But I suggest that we keep it in mind, because we must
ensure that any new symbols are connected to ones that are grounded.
Peirce noted that every proposition stated in any language, natural
or artificial, must have at least one index to link it to its referents.
That index could be outside the statement itself, such as a pointing
finger. But more often, it's a name whose referent is determined by
And I would also note that the *most* frequent method of symbol
grounding that people use is based on communication with other people
by means of natural language. That is why comments are essential for
telling us how to use any formal notation. The ideal comments are
ones that can be stated in a controlled natural language that a
computer can relate to the formalism automatically.