Okay, so it's no big secret that ENTP's are one of the most argumentative types out there. However, I've been trying to understand why we as ENTP's like to argue so damn much, and I believe that I have come up with an answer. I was looking at this thread on personality cafe started by the user "ENFPleasantly" and starting looking at how Fi manifests itself in the ENFP....
[ENFP] The phases of an ENFP: growth
Basically the article states that Fi beliefs are a source of major strength for the ENFP. In fact, the stronger the Fi user believes in something, the stronger they will fight for it. Beliefs and values for Fi users almost remind me the story of "The Three Little Pigs". Something that the Fi user barely believes in is almost like the straw house that the three little pigs built: It will provide mild resistance, but it's not that hard to make it crumble to the ground. If the ENFP has a mild belief in something, then they will provide an okay resistance to something, and it will be harder to make it crumble, but will a little force their wood house may crumble. However, when an Fi user has a very strong belief in something, it's almost like a brick fortress is built in their minds: nothing can stand in the way of this belief and penetrating through it would be like trying to penetrate an actual brick wall.
So I was thinking about this, and I believe that a similar principle can be applied to the Ti function in ENTP's. For Ti users, understanding things, defining things, and figuring out how they work is key. It is absolutely essential for ENTP's to understand things, and they dedicate a lot of time to this practice. Now when another individual challenges an ENTP's understanding of something, and says that they are wrong on an issue, they get very defensive and often argue their point very aggressively. The reason being again, is because understanding is so important to them. Now I believe that Ti's understanding is just like Fi's beliefs and values: The more time that an ENTP has dedicated to understanding something, and the more thorough understanding they have come to on an issue, on a thing, or whatever, the more aggressively they will argue for it.
What do you think of my theory?