Of course they are. That's also the message of Edward Gibbon's Decline and Fall of the Roman Empire. Think about what conspiracy means, and I posted my own opinion (see article three section three being my opinion, basically) elsewhere. A conspiracy, well take the civil war as an example. "Let's get together and make a plan to divide the country". Now that's the definition of rationality. A ratio is a fraction, the comparison of two numbers, specifically the comparison of a part to the whole. Totally rational. (Now, that's not the same as saying reasonable. the two words, rational and reasonable, do mean different things).