Sometimes as the writer we know more about the character's philosophy than they do. Okay basically we pretty much always know more if we developed a full character. We know the places they lie to themselves and those where they won't want to admit to anybody their truth.
Fully knowing a character does require knowing their philosophy of life. This is probably as true or more so for villains especially if the villain is a character throughout the story. If a book has only a place holding villain as an opportunity for the hero/heroine to show their stuff, then the writer might feel they don't need to know much about why the attack/s happened. I think it still matters as otherwise it isn't a real villain attack, it's an author attack.
There isn't much I enjoy writing more than villains and I sometimes give them their own point of view because it's fun to write their motivations as they plot and the reader gets a chance to know why they've done what they did. Other times I let them show their character and philosophy only through their dialogue with the main characters.
From Evening Star is an example of one of my villains and how in one scene he shows a lot of his life philosophy by actions and dialogue. I decided to use his point of view in this book because the only other POV was that of the heroine and I wanted something that took the reader more into the danger of the situation.
Gus leaned against the table, his mind on the football game he'd just switched off and the five hundred bucks he'd won on its outcome. His hands toyed with a length of rope, twisting it into a knot, pulling one end, and watching as the knot pulled free.You know a lot about Gus's philosophy of life after that brief piece of text. More will be shown each time he appears dealing with his gang. He's shallow, pleasure oriented, no patience, and only really cares about himself. He trusts no one very much and enjoys inflicting discomfort on others.
He looked up when the two men, one small and quick, the other tall and handsome, came through the door. "About time you two got back," Gus said with a grin. "You get it?"
BrotherRat set a package on the table as he sat on a chair at the table. The other man leaned one broad shoulder against the door jamb.
"You guys have any trouble?" Gus asked, opening the package and assuring himself that everything was in order.
BrotherRat said, "It was a piece of cake. If I hadn't seen it for myself, I'd never have believed how smooth it could go down."
Gus rubbed his beefy neck thoughtfully. He glanced toward the sullenly handsome man, who was moodily staring into space. "You don't look so pleased as Rat here, PrettyBoy."
"I told you I don't like being called that."
"Too bad," Gus said with a chuckle. "I name all my boys. It's safer that way. So, PrettyBoy, what else is wrong?"
"We took a lot of risk for nothing, so far as I can see." He gestured toward the box. "What's that? A couple of hundred G's." He reached into his shirt pocket for a cigarette, lit it, and took a deep draw, exhaling the smoke. "We go to the slammer for that kind of money, and I say we're fools."
"You got a brain, PrettyBoy," Gus said with a laugh. "I like that. But don't worry about going to the Big House. Who says it's the problem?" He shaped his rope into a noose.
Gus played with the rope watching as the younger man paced to the other end of the room, his body as streamlined as an alley cat, his face when he turned that of an angel--in this case, Gus grinned, more likely a dark angel. Gus liked pretty things around him. It was one of the things that had caused him to take the risk of bringing in a stranger based on someone else’s say. One of these days he’d show PrettyBoy some games he might like, or if he didn’t, well that would be even better. He grinned with anticipation.
If someone told him he had a virtue, he'd laugh at them. Gus lives for pleasure and gain-- for himself. Anyone else who counts on him is a fool, and he'd laugh at them too. The thing about Gus is-- he knows all of this about himself and is fine with it.
He would never put a name to his philosophy of life; but if the author felt compelled to do so, she'd call it egotistical hedonism on the shallowest most base level. He's a sadist and psychopath which means no concern for rules-- only his own benefit. If he wasn't so smart, he'd be less dangerous. If he didn't operate so much on that base level, it would be harder to beat him.
Someone like Gus is easier to identify than like minded sorts who have risen up the social ranks and can hide their nature more effectively while they operate just as ruthlessly.
Since I don't have an image for Gus, I used one of the author who created him. She doesn't look nearly as ruthless as he does-- unless, of course, she's one of those who has learned to hide her ruthlessness. You never know, do you...