# What is this process/action called in English?

it is a fairly generate question regarding a terminology.

People without science or engineering discipline makes an unfounded claim X, but people with such discipline start with proven facts A, B, C, D, and step by step they derive and prove using proven principals, so that what they conclude is mathematically or scientifically sound and without any flaw:

From A and B, X is derived

C, D => Y

X, Y => Z


What is this process/methodology called generally? Is it called "derive and prove"? I had my Tertiary education in China so I don't know the English terminology for this. Thanks!