What is the ideology behind the french revolution?

Answer 1

Marxism (as Karl Marx was only born in 1818 I find this highly unlikely)

The main ideology behind the French Revolution is believed to be that of equality. The third estate (the peasantry) were living in extreme poverty, in some cases communities were intentionally starved. This poverty can be accredited to France's overambitious interest in foreign affairs, such as the American Revolutionary War and the nation's colonialism-driven exploits, although historians also draw attention to the low production of crops (particularly as potatoes were unable to be grown during this period due to a believed El Nino effect).

Essentially, the peasantry were forced into unsuitable living conditions which caused them to revolt against the totalitarian Louis XVI. Though this tirade for equality could be considered at its roots to be Marxism, so too could the American Revolutionary War be considered founded on such ideologies. Evidently, class equality does not equate to Marxism, merely a form of social, though in this case the class division was so great that the French Revolution merely worked to abolish such differentiation.