Claims and Reasoning
By using practical, step-by-step instructions, Matthew Allen's Smart Thinking: Skills for Critical Understanding and Writing can help readers develop their analytical, critical-thinking, and effective communication of arguments and justifications skills. With a solid background in information, the book combines an approachable and plain language.
In the chapter: Claims and Reasoning Using claims as conclusions and premises
Explaining "why and how" the evidence supports the argument is what is meant by reasoning.
Included within ought to be a description of the fundamental scientific idea behind the evidence or data.