"I am old, so stuff is harder to learn"
That is what I call "the fallacy of the old man". That is a dangerous sickness, and it is contagious...
When he says that, it gives enough reason for another old man to stop learning, thus giving a second "fallacied old man".
This is the lamest excuse that someone would tell you to justify their ignorance, incompetence, and unwillingness to learn.
I'll tell you the truth :
Knowlegde is like money.
The more you have, the more it comes.
The more you know, the fastest you learn.
If you think your brain is slow, it is just atrophied by your inactivity. That's all.
The other side of this fallacy is this one : "I can't be a genius like them, life did not give me the chance"
That is the second fallacy. This is what someone who has no idea about how much time the "genius" spends reading books and practicing.
If they learn things 10x times faster than you are it is because they spend 10x more than you on it.
This is the excuse of someone that need to rest in front of the television, when the genius go back to work, read books, learn, repeat, note and practice his craft.
If you are incompetent, just admit it and accept it -that's perfectly ok, you can't know everything-, but please don't be lame.