Purpose vs. Cause
In English, we often use "why" for almost everything. In Polish, there is a clear distinction between asking about the purpose of an action (what for) and the cause of a situation (why / for what reason).
Po co: What For?
When you want to know the intention, goal, or purpose behind someone's actions, use po co. It literally means "for what" and looks to the future: To what end are you doing this?
Dlaczego and Czemu: Why?
When you want to know the cause or reason behind a situation, use dlaczego. It asks about the facts or events that led to the current state of things. You will also frequently hear czemu, which means exactly the same thing but is slightly more conversational.
Spotting the Difference
Notice how the choice of question word changes the focus. Use po co when questioning someone's motives, and dlaczego when investigating facts, states, or underlying causes.
You might build a shelter with a specific goal in mind (po co), but the door is locked due to a factual reason (dlaczego).
Putting It Together
In a tense situation, like surviving an imaginary crisis, you might understand the cause of someone's feelings, but still question the logic of their actions.
