Well, it's hard to exatcly define this word. It's more like a filter word. For example, you can easily omit that word in your sentence and the meaning won't really change. Ведь just adds more expression to the sentence, it's like an emphatic word if you know what I mean. It's like this:

А в таком виде в театр не пойдешь - You can't go to a theater dressed like that
А ведь в таком виде в театр не пойдешь - It's an absolute truth (commom sense) that you can't go to a theater dressed like that