Oaktree Capital Management co-founder Howard Marks says that investors should see the drop in oil prices as more proof that markets are irrational and macro forecasting all but impossible. Instead of trying to guess which way prices will go from here, he’s looking for the securities (high yield debt in particular) that are getting unfairly pummeled by investors heading for the door. “For the last 3 ½ years, Oaktree’s mantra has been ‘move forward, but with caution.’ For the first time in that span, with the arrival of some disarray and heightened risk aversion, events tell us it’s appropriate to…