|The best way to deal with an employee who leads off with an argument is to talk about this behavior after he has calmed down. If you try to deal with him while he is in an argumentative mode, things will only get worse.|
After the storm has passed, you should sit down with him to review what happened. In such a discussion, it will be very important to deal with undeniable facts and behaviors. If you approach him with labels, impressions, and evaluative comments, you already know exactly what he will do.
Rather, give him a specific and well-illustrated overview of his most recent behaviors, and then tell him that they are working against the very outcomes that he would like to achieve. He needs to clearly understand that by instantly arguing with you, he is likely to find increased resistance and decreased likelihood of accommodation, acceptance, or support.
The next step is for you to model some effective ways to voice disagreement. He needs to understand that listening, empathy, and trust-building are far more powerful persuasive strategies than arguing. As time passes, if you see him showing some improvement, be sure to show him some positive feedback. Presumably, he will not argue with that.