You had an argument with your boss, David Sarif, and won.
Once you've returned to Sarif Industries after the Lawrence Barrett fight you'll need to go talk to David himself. Before you do, make sure you talk to Pritchard first. He'll actually contact you before hand, so go see him.
Once you've spoken to Pritchard, head up to Sarifs' office and before you speak to him save your game. During this dialogue the choices you make will help you win the argument and unlock some emails that you'll need to view for the 'Deus Ex Machina' achievement. Use the following choices to win the argument:
After you've unlocked the achievement, you MUST head to your office and read the new emails. If you don't then you will not be able to unlock the 'Kevorkian Complex', 'Acquaintances Forgotten' and 'Deus Ex Machina' achievements later.
Perhaps the outcome is randomized like other conversations. I retried getting into the police station using the exact same dialog items and it didn't work, unlike the first one where I just screwed up using the influencing ability when it was offered to me.
However, Refocus, Defend, Placate, Defend did work for me...
yes you need to talk to pritchard to confront sarif for this achievement i forgot exactly what i did, but basically i read the script choices and thought "what would a GOOD person say" i'm going for as nice a fellow as possible on this playthrough
Not sure how you guys won the conversation with Sarif with Redirect, Defend, Placate, Defend. It didn't work for me whatsoever. He just got hot headed. All I did was keep redirecting Sarif - Which allowed me to respond to David questioning why he was evading. This worked out way better. NOTE: I am on "Give me deus ex" difficulty.