Didn't want to further clog up Hitman's journal so thought I would start a new thread. I used to work as a quant for one of the largest and most successful CTAs (you can find them on that iasg list). My job was to develop automated trading systems. Their entire operation is completely systematic with no discretion involved, and they make a lot of money. So system trading works, without question. I have also been fortunate to observe some great discretionary traders. They are able to use information that can never be coded into a system effectively (such as analysis of sentiment, news and market psychology). An expert discretionary trader will beat a great system, especially in terms of consistency. My approach has been to combine the two. Having watched the markets for a number of years, I have developed a theory on why they move (based around sentiment) but this is impossible to 'mechanicalise'. I also have some good technical trading systems for these markets. I only take a position when both (system and my discretionary opinion) are in agreement. My aim is to beat my system. I will often get a signal from my system and I will think to myself, 'there is no way this one's going to work', so I will stay out. Comparing my real-time results to those if I had traded the system without intervention, I have made a slightly lower annual return but a much lower drawdown and smoother growth. This approach has worked well for me, and it suits my personality. I am not comfortable taking a system signal blindly, nor am I comfortable trading purely on my gut without knowing the probabilities (as defined by a technical system) are in my favour. So in conclusion, I don't think the argument needs to be system or discretionary, as combining the two together can give a good result.