Pallas is not only the non-aggression principle and ethics in the horoscope but also an integral part of our processes for making significant decisions. When Pluto aspects natal or progressed Pallas on a person's chart, the person may find his/her decision-making process under pressure or compromised.
So when we learn that brilliant actor Philip Seymour Hoffman apparently made the decision to take a dangerous amount of heroin this weekend, resulting in his death... we might be moved to look for such a transit against his natal or progressed Pallas. It is easily found: transiting Pluto is opposite his natal Pallas and quincunx his progressed Pallas. The latter is conjunct his natal Jupiter: his fateful decision has been very public. (time of day for birth and death are unknown at the moment, but not important for this consideration)
Other writers have already commented on other facets of Hoffman's astrology for this unfortunate event.