Ideology via a dictionary:
"A system of ideas and ideals that form the basis of economic or political theory and policy"
"The set of beliefs characteristic of a social group or individual"

Ideology via experience:
In practice, an ideology finally distinguishes itself by its loyalty to its own values ahead of other all considerations - like facts for instance. Under pressure, an ideologue is identifiable by their rejections out-of-hand of conflicting evidences or logical critiques. Typically in preference they will attack their detractors' ethical integrity. These ad-hominum reactions can vary across a wide spectrum: From thought-blocking clichés (e.g. of "political correctness" and “bleeding hearts” from the Right) to name-calling (from "sell out" to "counter revolutionary" from the Left) to lethal violence (Fatwa-approved assassinations or the most brutal execution of heretics, by those of a more pious inclination).

It seems then that ideology is not merely a framework of ideas supporting ideals and beliefs, but is actually constructed as kind of fortress against reasoned objection, and by extension, against reality itself. While not all ideologies are so malignant, it seems that as intrinsically anti-rational constructions, all are ever prone towards a slide into the abyss.

While bracing for the shock of the next ideological train wreck, a fairly obvious question comes to mind: How best then to deal with unjust and damaging ideologies?

The relativist's plea for universal acquiescence can't be a long term solution as the world grows ever smaller - ultimately forcing the consequences of irrational value systems upon all bystanders and unfortunate ecosystems who happen to be in the way. I used to think comic derision was the most effective response until they started murdering cartoonists (thankfully my own country is merely content in jailing you for deriding the esteemed). Violence as a solution seems only to fuel the growth of conflicting ideologies - and is seldom very much fun for long. Finally, as outlined above, ideology seems specifically designed to resist critical thought and empiricism.

If philosophy can't solve the problem directly maybe it still has some good advice. I'd appreciate any practical thoughts on this problem which seems to have become more pressing.