In reductionism a problem is addressed but studying the properties of its parts. Therefore a complex system is broken down into its component part and each part is studied individually by various approaches. It bills the descriptions of system from the descriptions of subsystem that a system is made off and not considering the relationship between the sub systems.
For example, reductionism considers the biological system to the composed of molecules with certain structures or a molecule to be composed of atoms thus reductionism always understand the nature of complex entity by breaking them into much simpler or more fundamental components.
Holism:
In contrast, the concept of holism believe that the relationship between the part and the system as a whole to be more symmetric than in reductionism. The holism focus on the relation between the sub system that is their inter connectedness, inter dependency and inter action. Thus in holism the natural system and their properties are viewed as whole rather than collection of part. In total, in holism the whole is more than or difference from the sum of its parts. There are no necessary contradictions between the two approaches one focus on the property of the part where as the other on the relationship between them. When put together they stand as suplemtary rather than conflicting. In general there are no philosophical, ideological or practical contradiction between reductionism and holism scientifically.
Systems thinking:
Systems thinking is the process of understanding how things influence one another as a whole. It is an answer to the increasing complexity of the environment in which we live as a function. The systems approach is to identify a system, and then explain the behaviour of properties of whole system and to explain the behaviour or property of the sub system in terms of rolls or functions of the whole system. The systems thinkers focus on the system as a whole and do the