It is irrational to claim to be rational when we know we have inbuilt propensity to irrationality!
Ah, but this gives me the chance to pull out one of those infamous
Star Trek quotes: From the TV episode, "A Taste of Armageddon" - Kirk addresses Anon 7 who has just called him a barbarian, to which Kirk READILY agrees. But he then says (paraphrasing) that one difference between "civilized" and "barbaric" is that the civilized man can say, "Today I will not kill." And mean it.
I claim sufficient control over my irrationality to say that sometimes I am consciously rational.
Then, of course, when I DO go off on a tangent, you can compare me to an irrational number because those go on forever...