Against Couturat's rule of reversibility as applied in Ido we must now set de Wahl's rules of flexional coalescence. These I will quote fully as I believe that de Wahl has made a distinct contribution to linguistics in defining very closely the function of the particles in flexional derivation. I should add that, by describing the naturalistic system Occidental as a flexional one, a reservation must be made: most words follow agglutination but the very fact of admitting flexion introduces a new aspect which has never before been used in a constructed language and therefore calls for a separate classification of that scheme.
Flexion, then, is governed by three rules: To form nouns from verbal roots
we detach the infinitive /r or -e/r [vid-e/r, vid-]
to obtain the perfect stem.
(1) If, after removing the grammatical termination the stem ends in a
vowel, add -t or change -y into -t [crea/r,
crea/t, crea/t/or; atiny-e/r, atin/t, atin/t/ion].
(2) If the final consonant of the stem should be either -d or
-r, change into -s [decid-e/r, deci/s, deci/s/ion].
(3) In all other cases (with six exceptions) the removal of the infinitive
/r or -e/r gives the required perfect stem [duct-e/r,
duct- [duct/ion]]. Inversely, to form verbs from nouns and adjectives,
we remove the endings and obtain the perfect stem. By adding /r
or -e/r we will obtain, in most cases, the infinitive
[decora/t/ion, decora/t, decora/r].
As we have seen, de Wahl has been able to express clearly the character of flexional change, and in so doing has been able to retain many international words without mutilating them. In selecting his affixes, however, he had to make a concession to international usage, namely to define very loosely the meaning of these suffixes. In fact he was forced to admit several affixes with a more or less identical function, shaping his words in analogy to ethnic usage rather than a clear definition of the meaning of his suffixes. Where the autonomistic systems retained monosignificance at the cost of distorting - in some cases - the international aspect of a word, the naturalistic systems retained the international aspect at the cost of precision of meaning, a fact which becomes only apparent when the languages are tested for scientific purposes.
I have deliberately discussed indirect derivation first, in order to emphasize the essential difference of both schools. But let me mend the omission: In direct derivation Occidental commits itself neither to the extreme principles of Esperanto which also uses affixes as independent words [ne = no, not, non-; ne/i = to deny, negate], nor to the extreme logicality of Ido in deriving verbs from nominal roots, but limits its use to five distinct cases, (1) to provide wit h[arm-a/r = to arm], (2) to use as an instrument [martell-a/r = to hammer], (3) to secrete [sangu-a/r = to bleed], (4) to act as [judic-a/r = to act as judge], and (5) with adjectives and participles, to produce this quality [sicc-a/r = to dry].