How do I know when I ‘try something out’ in practice that my assessment of its effectiveness is valid? Might I not just be fooling myself, wanting to see some improvement? If there is a group of us, how can we guard against fooling ourselves collectively? Is what I am noticing going to serve in other situations, and if so which ones, or is it entirely situated in the circumstances which gave rise to it? How can I recognise the scope of applicability of an action?