This book concerns with some philosophical issues and debates have been running among philosophers of science. This book is a collection of some articles on science. believing that philosophy of science is a critical-analytical approach, my aim, accordingly, was to deal with some scientific disciplines such as physics, biology and astronomy. I tried throughout this book to present new different account based on what I call structural idealism, where priority is given to structure, law and regulation over matter and properties. As a result, I discussed some philosophical claims using structural idealism.I tried to display that some philosophical accounts such as constructive empiricism, metaphysical realism and structural realism suffer sort of inconsistency.It has been shown that physical theory implies certain forms of pregnant structure that can not be explored within various versions of realism.It is shown that notions such as pregnant structure and lawfulness are well presented within structural idealism