I was listening to a song and decided to check the lyrics to it.

<http://www.kasi-time.com/item-74499.html>

夜風に吹かれ 考える 好き 嫌い 嫌い 好き 繰り返す

Since there were no question marks, so it made me doubt if it was a question
being asked in the lyrics. Also, when I did a dictionary search for でしょう

[http://classic.jisho.org/sentences?jap=%E3%81%A7%E3%81%97%E3%82%87u&eng=](http://classic.jisho.org/sentences?jap=%E3%81%A7%E3%81%97%E3%82%87u&eng=)

Some have question marks, while some don't.
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grammar song-lyrics punctuation
Do you need a question mark to indicate a question in Japanese?
Nope, it's optional. The final particle か indicates that the sentence is a
question, so that can be seen as the question mark of Japanese. In fact,
adding a question mark when there's already a か can seem redundant.

That said, you'll find it used a lot anyway, just because sometimes people
want to use it. But it is definitely a casual thing, so you'll only see it in
casual writings, like manga. You won't find it in anything formal.

Edit: after reading the song text more closely, I'd also like to add that
sometimes, as occurs a few times in the lyrics, it's necessary to add a
question mark in writing to show that it's a question even if it doesn't end
in か. In speaking it is clear when this happens, but not in writing. This
still only applies to casual works, though, because formal sentences will be
grammatically set up to indicate that it's a question without the need for a
random question mark.
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The short answer is 'no' because all questions end in 「か」 in any "official" or
"formal" writing. You just know when you see a question.

I never even learned how to use a question mark in elementary school. I was
surprised to learn that it was regularly used in English when I started
learning English in junior high school.

In non-official and non-formal writing these days, however, the question mark
is used everywhere, especially when the questions are short as in:

「マジで？」= "For real?"

「[車]{くるま}で[行]{い}くの？」= "Are you going by car?" or "Are you driving (there)?"

Even today, we would not often use a question mark at the end of a longer
question ending in 「か」 in an informal setting like a personal letter. It could
look "funny" if you used one. Old habits die hard.
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Spoken Japanese in particular tends to use intonation to indicate whether or
not a question is being asked, regardless of the final particle. (If it's a
question, the speaker's tone rises a bit at the end, just the way it does in
English.) I'd assume that's what's being done in the lyric, or what the
lyricist thought people would assume automatically. They could easily have
used "?" (and should have, honestly ^_^b), but adding "か" would have thrown
off the rhythm.

It also depends on context: In these lyrics, if the singer's been mulling over
their feelings about someone else earlier in the song, it could very well be
"I love them. I don't. I don't love them. I do." If they've been wondering how
someone feels about _them_ , it's definitely a question.

With regard to でしょう, since it's sort of a "guessing" word, it technically
always leaves room for someone to deny the assumption of the sentence, but it
isn't always used to ask questions, per se. "疲れてるでしょう" would be "You must be
tired" or "I bet you're tired", but if you're using it to ask whether a house
guest wants to go to bed soon, you'd probably raise the intonation at the end,
and in writing, if you wanted to keep the syllables exactly as they were (and
avoid adding か) you'd need to tack a question mark on the end to show that.
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