Anecdotal Evidence

I had the opportunity over vacation to witness several episodes involving my son, Moses, who is three and half and my brother, Vid, who is seven that have given me a great deal of anecdotal evidence that the age of reason is indeed a reasonable idea.

Proof One: The Quadet (Chocolate)
Shortly after noticing that the 4 or 5 bars of chocolate left over from S'more making are missing Moses jauntily walks out of the bedroom that he and Vid are sharing, his mouth smeared with a brown substance, and a BIG grin - clearly unable to repress his great joy. He announces in a loud voice to all in the listening area, "We ate AAAALLLLLLLL the quadet! It was VEEEERRRY naughty!"
Vid looks at him as if to say, "Have you no sense?! You are not required to incriminate yourself, or ourselves!"

Proof Two: The Pond
The next door neighbor of the vacation house that we use on vacation has a backyard pond, the kind with a little waterfall and it's about 4 ft. deep. I did not know this. I did not know this when Vid and Moses were quiet for 10 minutes. I found this out when we called them and Moses responded, very matter-of-factly, that they were throwing rocks in the pond. I imagined them throwing the little pebbles that make up the driveway and told them to stay away from the neighbors pond.
Another thing that I did not know, a thing that we learned from the neighbor the next day, and from the police who accompanied him, was that the boys had actually been throwing in large pieces of the slate WALL that surrounded the pond. Vid also dumped a gallon bottle of algae killer and killed all the fish. We do not know yet if they tore the lining to the pond.
I believe that Vid was duly chastised by the presence of law-enforcement and a stern talking-to by my parents. When all this came to light David and I were out. When we came back Moses was very upfront in his confession that, "We did DAMAGE. Lots of damage. It was a very naughty thing to do." I wouldn't say that his response was un-remorseful, just unaware.

Proof Three: The Fight
The boys are playing with some blankets and some dogs. A lot of rolling around and laughing and such. Suddenly there's a kuffuffle and my mom steps in to intervene.
Grandma: What happened?
Moses: He pushed me!
Grandma: Vid, why did you push him?
Vid: Because he hit me!
Grandma: Who hit first?
Moses: He did!
Vid: He did!
Grandma: Well, who is telling me the truth?
Moses: He is!

He clearly has not reached the Age of Reason yet. Vid is so much wiser in the ways of the world - he knows it is just not a "reasonable" thing to be so upfront with ones misdeeds while Moses is just happy to have had some quadet!