"You like everyone."
Translation:Du magst jeden.
They mean that in accusative case, the nominative "der" becomes the accusative "den", you can see a little chart here: http://www.germanlanguageguide.com/german/grammar/demonstrative-pronoun.asp
In the case of "jeder" it becomes "jeden".
You can't say "Du magst alles" because in normal speech that translation would mean "You like everything". Except maybe philosophical language, the term "everything" covers exclusively only inanimate objects, things. Quite the reverse, everyone, as object of the sentence to be translated, only covers animate objects - plants, animals and people.
- What implies that 'everyone' in this sentence is a masculine noun? Is it "der Jeder" - or is it just conventional wisdom of sorts? 2. If I were to say "Du magst jedes" would it imply that everyone in that group is a child? "Du magst jede" - and now everyone is a female? or is it "Du magst jeden" in all cases? Am I nuts :) ?
- "jeder" is gramatically exclusively of masculine grammatical gender and this applies whether it plays the role of a noun as in "Jeder in meiner Klasse hat ein Auto" or the role of adjective as in "Jeder Mitschüler meiner Schwester hat ein Auto."
- If I were to say "Du magst jedes" it would imply that everyone in that group is a child. Correct. "Du magst jede" - now everyone is a female, yes it is so. ...But with girls, think of grammatical gender of German word for a girl, which is DAS Mädchen, neuter gender! With this idea on the speakers mind, "Du magst jedes" is only correct!