Psionic Powers: Brute Force vs Will

[Kelly Pedersen]

Originally Posted by Crakkerjakk

How is failing a mental defense roll that different from failing a dodge roll v. a high ST grappler or HMG fire?

Well, there's a few things going on there. First, it's never possible for a defense to be impossible, if you get a chance to roll - a critical defense always succeeds, no matter the penalties. So that provides some level of defense priority.
Secondly, physical defenses usually have more ways of boosting them than mental defenses. Someone who's dodging can retreat, dodge and drop, find cover, all-out defend, etc, while parrying and blocking can also be raised very high by investing in the relevant skill, and most GMs are more willing to allow extremely high (20+) skill levels then they are to allow extremely high basic attributes. Also, physical defenses are more easily layered - you can buy armor that can save your ass even when your active defense fails. Most mental defensive gear simply add to your resistance roll, rather than providing a backup defense if your first fails.
Finally, people often react worse to mental "damage" than to the strictly physical. Players tend to like to think of their characters as perfect avatars of their will; taking that away can lead to more of a sense of violation and anger than simply losing hit points could ever inflict.

For all these reasons, I agree with GURPS' designers that a bit more primacy to mental defense than physical is a good idea.