(asked by Emlyn from Liège, Belgium)
That’s quite simple really.
Most democracies have one of the following:
-A President and a Vice-President.
-A King and a Prime Minister.
-A Chancellor and a President who is just a joke (barely the equivalent of a Speaker of the House)
Let’s not talk about the latter because we don’t care about it (sorry about that Germany).
We are now left with choosing between a King and Prime Minister or a President and Vice- President.
Thing is that, back then, France was not a democracy and had a King and a Prime Minister, so when we killed our King (well, the one we killed was not the very last one, but that’s beside the point), it was time to decide what to do. The logical choice was to have a President and a Vice-President…
But one event in particular prevented that to happen:
The US just got their independence and decided to have a President and a VP.
And one thing you need to know about the French is that they have a vital need to do things their own way. They hate being followers. In their mind they are the one that enlighten the world with new things (and in that case it worked as several other countries chose the French model when they became democracies, Romania for instance).
So a decision had to be made and the vice-president was its collateral damage and since that day we’ve had a President and a Prime Minister.
It was the logical choice since -with the way the French system works- the President has more of a role of an elected monarch rather than the real chief of the executive, role which is the one of the Prime Minister.
Also, you need to know that things might change soon as I type these lines. Our new President is not content with that role and has already taken over the role of Prime Minister (everybody is currently wondering what the real one is for) as well as several other ministers’ to the point that France will soon have a one man government. But if France will still be called a democracy in that near future still remains to be seen.