Right after WWI, the military (and politicians) are divided in 2 groups:

-The first one led by Foch is offensive. Its' advantages are the ability to strike with an early preemptive strike against rising menaces, and to support the new allies of France (GB is distant, Russia is hostile) Czechoslovakia and Poland. De Gaulle published in 1934 "vers l'armée de métier", is a plea in favor of a strong by small professional army relying on armored division. While not revolutionary, (Liddell Hart, Guderian and the Russian had developed similar concept), he accurately predicted the role of the tank: "In front of the attacker would open the path of victories, deep "effects" fastly extended will cause a general collapse for the enemy, like the rupture of a pillar would cause the one of the cathedral". Even earlier in 1921, general Jean Estienne (the father of the french tanks) called for a 100,000 man force equipped with 4,000 tanks and 8,000 transport vehicles that could break an enemy's front and advance 80 km in a single night. (obviously the figures are unrealistic and unbalanced, it wouldn't be viable in practice, but the overall idea is here!) Until the very end of his life he would oppose the use of tank for support purpose.

This wasn't the path chosen by the army as you surely have noticed. There are many problems with this doctrine. The left wing in France fears the military, they fear that the army may launch a coup d'état and end the IIIrd republic. The second one is the conservatism of the army, the formerly innovative (but no more) and young general of WWI are not yet retired, they are preventing the young one like De Gaulle to reach the high commandment. The third issue is the pacifism in France after the horrific casualties in WWI, the people, politicians from the far left to the far right are pacifists. There is a well known slogan "Mourir pour Danzig?", (die for danzig?) questioning the necessity for French to intervene for the sake of Czech or the Poles.

-The second group led by Pétain is looking for the "absolute inviolability of the territory". The most obvious application of this doctrine is the construction of the Maginot Line. Its' strategical aim is to outlast Germany thanks to a blocus just like in WWI and to rely on the superior resources of the allies. The obvious issue is that eastern Europe is in the German sphere of influence and the USSR is even a major trade partner... Daladier in 1939 is foolish enough to suggest to bomb the oil field of Bakou using French (mediocre) bombers that would take of from the middle east... He believed that this sole move would cause the collapse of both the german and soviet economies... (fortunately the option was dismissed)

On a tactical level, it's pretty much the lessons of WW1... The task of the armies is to maintain a continuous front and seal any breach as fast as possible. The infantry had the main role, supported by tank and artillery. Offensive operations would be created by massive artillery fire and rigid advance of the infantry. (The French predicted that they could be rearmed suitably by 1942 to launch massive operations...) The army completely lacked initiative, each order had to come to the (many) upper echelons before being validated, an order took 2 hour to be transmitted from the headquarter to the front line... As for tank, the high commander had no idea how to use them and has no less than 3 or 4 doctrines at the same time: infantry support(independent tank brigade), use of great cavalry tank unit (unit is DLC: division légère de cavalerie), rupture/counter strike and sealing of breach (unit used are DCr: Division Cuirassée).. Those armored divisions are significantly worse than Panzer division as they mobility, modern communication tool, inter arm ability and support are much weaker than the panzer division...