Thanks to this article, I've come to understand particles much better and why they're important, but does it change in casual spoken Japanese? Are some particles okay to drop whereas others are kept? Thanks in advance.
Sure. "piza wo taberu?" can be "piza taberu?" and that's fine, even normal.
> (including pronouns)
This is different and I think there are a few misconceptions bundled up in this assumption.
1. Particles don't exist on their own; they're permanently linked to the word that precedes them; if you've ever studied a Romance language, you can think of them as a way of declining nouns.
So "watashi wa" is the nominative, "watashi wo" is the accusative.
2. Pronoun dropping is done in the sense that the pronoun is not essential to the sentence and can be inferred from context.
For example, if you and your friend are eating and you ask "motto taberu [gonna eat more?]," nobody's going to be confused about whether the subject of that sentence is "watashi wa" or "anata wa."
It happens in English, too, but people overthink it a lot when presented with it consciously in Japanese.
John went to the shop. John bought a cake. John took it to Bill's house. John and Bill ate the cake.
It's not grammatically wrong, but it's clunky. We just use pronouns to sound 'normal' in English:
John went to the shop. He bought a cake. He took it to Bill's house. They ate the cake.
In Japanese instead of changing a noun (John) to a pronoun (he) you just don't say the subject if it hasn't changed:
John went to the shop, bought a cake and took it to Bill's house. They ate the cake.
Which, as you can see, is something that works in English at times too.
Tarō wa Noriko wo toshokan de mimashita.
In casual spoken Japanese, can any of these particles (wa, wo, de) be dropped?
> eiga miru?
> ano hon, suki?
> ame futte kita.
> okaasan iru?
And so on. But I don't think that's a rule you can work backwards from, it just describes all the cases that occur to me.
Japanese is a so-called "pro-drop" language, which means it's normal to omit pronouns completely when they can be inferred. "Watashi wa tabemasu" would only be used for specific emphasis, as in: "I specifically (as opposed to somebody else you were just talking about) am eating." In any other context, it sounds unnatural, and you would just say "tabemasu" even in formal situations.
Separately, you can omit particles in colloquial speech when they're obvious. So for instance, in a polite setting you might ask "ashita wa, nani wo shimasu ka?" (meaning "what are you doing tomorrow?") But in a casual environment, you could say "ashita, nani suru?" and still be understood perfectly.
Watashi wa tabamasu. -> As for me, I'm eating.
Tabemasu. -> I'm eating.
It bears repeating: this depends on context. But you can see how "watashi wa" sticks out like a sore thumb, and you can instantly recognize novice Japanese second-language speakers because they say "watashi wa" all the time. And you'll later learn that "watashi" is sometimes an inappropriate way to refer to yourself...
I shouldn't say that the language relies on inference. Rather, speakers of Japanese rely on inference. It's like chaining functions in some languages.
Car.rent().driveTo(work).park().driveTo(lunch).wash().
By the time you get to the washing in the conversation, the car is hard to find in the sentence, and the driver never does appear. But they are both there if you go looking.
eg: Taberu (eat) or Hayai (fast)
It sounds like cavemen talk if you translate it literally, but it is perfectly valid japanese