Complex sentence: Science is defined as the knowledge ascertained through observation and experimentation, critically tested, systematised and brought under general principles while the philosophy of science is the investigation of questions that arise from reflection upon the science and scientific practice.
Split into simpler sentences: Science is defined as the knowledge acquired through observation and experimentation which is critically tested, systematised and brought under general principles. The philosophy of science is the investigation of questions that arise from reflection upon the science and scientific practice.