Ever since Frank Knight’s work in the 1920s, economists have made a distinction between risk (which is based on quantifiable probabilities) and uncertainty (which doesn’t lend itself to being quantified).
To take up this distinction again, you could say that we also find ourselves in a world where there is more uncertainty than risk, because the issues have become political in nature: uncertainty about the relationship between the United States and China – with all its trade, security and intellectual property consequences; uncertainty about Brexit… Market participants are at a loss to form opinions in these circumstances.