Without a read you should fold here then. Your read on the villain wouldn't be specific so that you know his hand exactly, but rather what type of plays have you seen him make. Is he a player that has raised out of position with dominated hands such as Ace-rag or King-rag? Would he make this move with a pair of sixes just as easily as a pair of Jacks? Does he overvalue hands like KQo and push with those? If he had a pair of aces or kings in the hole would he make this move or merely call here so he doesn't reveal the strength of his hand?

There are a lot of things you can use to build a range. It's not an exact science. You get better with practice but you should really start putting your opponents on hand ranges. I calculate those odds using PokerStove, a free program you can download. Download it and play with it away from the table. Use it when replying to threads like this one. You'll be surprised how much it helps your game. Get enough practice with it away from the table and decisions like this become second nature in the heat of battle.