There exists a field of epistemology or philosophy of complexity using contemporary scientific developments for questioning our relationship with reality, knowledge and science developments. This field is extremely stimulating and points at ways of thinking about safety science and risk management in general. This paper will elaborate on and present how the epistemology of complexity - focusing in particular in the challenge of articulating disciplines - offers concepts for tackling accident investigation and auditing of complex sociotechnical systems for at least two purposes worth discussing in light of complexity: safety and security. The discussion will be based on the presentation of Morin's "complex thought", and case studies presented in previous papers which develop these ideas but also from past and current research (since 2000) for the environmental French ministry as well as consulting works for the industry currently carried out by INERIS. This paper will therefore specifically address the issue of modelling (describing, explaining, interpreting, predicting) complex systems for safety and security purposes.