Theoretical term or statement: Term or
statement that stands for something that is not
There are quite a few kinds of theoretical terms
as defined: Terms for abstract things, like "democracy" or "justice";
terms for impossible things, like "square circle" or "negative squared
number"; terms for non-existent things, like "griffon" or "mermaid";
terms for possible things in the future, like "the next World War" or
"the state of the world in 500 years"; terms for things that are
revealed even if they may be unrevealed like "the inside of this" or
"the backside of that"; and terms for things in the past that
are not known, like "what Jezus preached" or "the precise number of
trees in London in 1700" etc.
The reason to define theoretical terms as I did is to stress that
everybody relies on some theoretical terms in most of his
that in fact most of the terms one uses are either theoretical or involve
theoretical terms in their definition.
And the reason theoretical terms are important is that any
that goes beyond the empirically known facts, and theorefore any theory
that makes any prediction, involves ipso facto theoretical terms, even
if these are very common sensical.
When speaking about scientific theories, it makes sense to use
'theoretical' in a modalized sense: Theoretical terms are such as cannot
experienced in suitable conditions with appropriate procedures. They may
still be both wholly justified and completely unavoidable, but must then
be tested and supported by their empirical consequences. This also means
that what starts out as a theoretical term (such as "atom") may become
an empirical term, and conversely ("phlogiston").