I had an argument with someone who said that unlawful sexual intercourse with a minor is not statutory rape because there is no word rape in 261.5
If that person wants to take that position, he/she is free to do so. Anyone who knows anything about this area of the law, however, will tell you that PC 261.5 is California's statutory rape law.
Because there is no mention of 261.5 in it so I thought it basically means that a minor cant consent to sex and if someone cant consent to sex that means its rape.
That's about the long and the short of it. The premise of statutory rape laws is the LEGAL FICTION that minors are incapable of consenting to sex. I say it's a legal fiction because it is nothing more than a creation of the law. For what it's worth, every state has different laws on this issue. California is one of the strictest states in that any sex with a person under 18 is statutory rape. Doesn't matter if the other person is also under 18. In fact, it doesn't even matter if the alleged "rapist" is younger than the alleged "victim." In theory, a 16yo boy could be prosecuted under 261.5 for "raping" a 17 1/2yo girl. Nor does it matter -- as it does in most other states -- how close in age the two persons are. For example, in many states, sexual intercourse that might otherwise constitute statutory rape is not considered to be a crime if the older person is less than X years older than the younger person (google "romeo and juliet law" for more info about that).
There must be some logical way of explaing that calling unlawful sexual intercourse with a minor a statutory rape is not wrong.
I'm not sure why you care whether this other person believes PC 261.5 is a statutory rape law. Maybe google "California statutory rape law," which I assume will produce tons of articles that discuss PC 261.5. Ultimately, though, if I want to call my car a horse, you can tell me until you're blue in the face that my car is not, in fact, a horse, and it won't matter to me. More to the point, regardless of what this other person believes, the reality is that PC 261.5 is commonly referred to as California's statutory rape law.
According to him you can only say it was statutory rape if person was charged with both 261 and 261.5 because there is such word "rape" in 261.
Wrong. I CAN SAY anything I damn well please. I CAN SAY, if I want, that it's a banana, even though the word "banana" doesn't appear in the statute. It's called slang or shorthand.
Also he said that some minors are more advanced than others and that it means something... and that a minor can consent to sex in a form that punishment is not as severe.
I have no idea what the last part of this sentence means, but it's obviously true "that some minors are more advanced than others." Some persons who are 17 are FAR more mature and emotionally capable of cosenting to sex than some 20 year olds. However, a courtroom is no place to conduct an inquiry into the emotional maturity of a minor, so the California Legislature has chosen to draw a clear line: under 18 = no LEGAL ability to consent to sex; over 18 = have all the consensual sex you want.