What has reason got to do with it...

A scorpion and a frog meet on the bank of a river. The scorpion asks the frog to carry him across. The frog refuses and asks, "How do I know you won't sting me?" The scorpion says, "Because if I do, I will die too." The frog satisfied with the proposition, agrees to give the scorpion the ride. In the midstream, the scorpion stings the frog. Paralysed by the sting frog starts to sink. Before drowning frog gasps, "Why?" Replies the scorpion: "Its my nature..."