There is no philosophy about Risk Aversion. Risk aversion is a behavior, we say a person behave in a risk averse way. The fact is, there are incountable number of possible events in the next period. Many of these events does not make a difference to a person. We group the outcome into equivalent classes and call them outcomes, so that each outcome does make a difference to the person. Now this person faces a few distinct outcomes. He has preferences over these outcomes. Some outcomes are worse off than others. The person prefers the bad outcomes not to happen. Hence the person faces risk, and has a risk adverse mind set.