What is the historical origin of the French présent conditionnel?

Question

What is the historical origin of the French présent conditionnel?

Did it perhaps start out as a tense?

BACKGROUND

I am referring to a grammaticalization process by which, in this case, a grammatical marker takes on an additional grammatical function.

In English, for instance, -ed, a tense marker that turns indicative present to indicative past, does double duty to change, this time, not tense but mood, i.e. from indicative present to subjunctive present. For example:

• I assumed that. (Indicative past.)
  
• If you assumed it, you'd be wrong. (Subjunctive present.)

Now never mind whether the second case is actually called "subjunctive present." What matters is that it serves as a statement about the present, or timeless statement--but in a certain mood.

I don't know that -ed began its career as a tense marker and later took on a second job as mood marker; but if that were true, it'd make a nice story.

Should seems to have had such a role expansion. From the Wiktionery article on it:

• From Middle English scholde, from Old English sceolde, first and third person preterite form of sculan ‎(“owe", "be obliged”). Related to shild and shildy.

Once a preterite, but now also a mood marker.

All this is only by way of illustrating the sort of question I am raising, and I am perfectly willing to be wrong about everything said above.

As for the French présent conditionnel, it looks rather like an "imperfect of future." Which makes me think there must be a very interesting story about how it came to be. Thanks.

Answer 1

The French conditional (like the Italian, Spanish, Portuguese, Catalan, Occitan and other romance languages one) has its origin in spoken Latin (no surprise here).

It is built by appending to the infinitive the ending of the avoir auxiliary at the imperfect tense:

- Je   parler [av]ais    → Je parlerais
- Tu   parler [av]ais    → Tu parlerais 
- Il   parler [av]ait    → Il parlerait
- Nous parler [av]ions   → Nous parlerions
- Vous parler [av]iez    → Vous parleriez
- Ils  parler [av]aient  → Ils parleraient

In older French, the construction is the same but we see the avoir conjugation evolving:

- parler [av]eie    → parlereie   / [av]oie   → je parleroie
- parler [av]eies   → parlereies  / [av]oies  → tu parleroies
- parler [av]eiet   → parlereiet  / [av]oit   → il parleroit
- parler [av]iiens  → parleriiens / [av]ions  → nous parlerions
- parler [av]iiez   → parleriiez              → vous parleriiez
- parler [av]eient  → parlereient / [av]oient → ils parleroient

In late spoken Latin:

- *parabolare habebam    → *parabolarea
- *parabolare habebas    → *parabolareas
- *parabolare habebat    → *parabolareat
- *parabolare habebamus  
- *parabolare habebatis 
- *parabolare habebant  

In classical Latin:

- *habebam *loqui
- *habebas *loqui
…

The conditional has then been built more or less that way:

"j'avais parler" → je parler avais → je parlerais

The imperfect is telling it happened in the past but the association with the infinitive is locating the action in the future of that past.

References:

http://bescherelle.com/la-formation-du-conditionnel http://asl.univ-montp3.fr/masterRECHERCHE/M1/j.bres/Conditionnel_coursM1A.pdf http://www.trigofacile.com/jardins/chronica/actualite/0801-temps.htm