This emendation would unquestionably have been welcome to Locke and Hume and Tooke, but historically it had to await two intermediate developments.
There are apparently intermediate cases between humans and species that communicate but do not have language in a human sense.
So to yield the desired results, a two-dimensionalist must hold constant some intermediate sort of content, such as Fregean or descriptive or narrow content.
This negative argument must certainly, in process of time, become altogether convincing, if many penetrating and able philosophers shall turn their enquiries this way and no one be ever able to discover any connecting proposition or intermediate step, which supports the understanding in this conclusion.
And if moral ideas are apt, without extreme care, to fall into obscurity and confusion, the inferences are always much shorter in these disquisitions, and the intermediate steps, which lead to the conclusion, much fewer than in the sciences which treat of quantity and number.
If, in some domain, the organisation of the behavioural repertoire is quite trivial and elementary, then there will be little harm in avoiding the intermediate stage of theory construction, in which we attempt to characterise accurately the competence that is acquired.
On the absence of intermediate varieties in any one formation.
On the nature of extinct intermediate varieties; on their number.
On the absence of intermediate varieties at the present day.
Admittedly, we learn from science that there are transitory or intermediate stages, and also intermediate systems; and this gives us hope that a reduction might be achieved one day. Moreover, it seems not at all improbable that recent tentative theories about the origin of life on earth might be successfully put to the test, and that we might be able to create primitive living organisms artificially.