Software development is empirical

One should learn from previous experiences and previous mistakes. Even better, one should learn from others’ experiences and mistakes. In software development, we have been very good at adapting knowledge from other industries. This has been especially the case with the manufacturing industry. From Taylorism to the more recent influences of Lean thinking, software development theories and practices have borrowed a lot from the manufacturing industry.

Having said that, we need to be very aware of the differences between manufacturing and software development. The former typically deals with repeatable processes, while the latter is empirical.
In manufacturing, a repeatable process converts consistent inputs into consistent outputs. Repeatable means that the conversion of inputs to outputs can be replicated with little variation. In repeatable process, a small variation of inputs typically translates to a small variation of the outputs. But this is not the case with software development.

Software development is not a highly predictable and repeatable activity. Software development is really about creation. The software creation process has too much complexity and variability to be treated the same way as manufacturing; software creation is an empirical activity.

The New Oxford American Dictionary :
em·pir·i·cal  adj. based on, concerned with, or verifiable by observation or experience rather than theory or pure logic:
In manufacturing, a great deal of work is about putting pieces together to build a specific product. In contrast, with software development these pieces are often created, re-created, or customized every time. The manufacturing discipline and its pieces of work are more mature, stable and well understood than the software discipline, and its pieces of work. 

Further, in software development a small variation on inputs can result into a big variation to the outputs. For example, small changes in requirements or architecture can result in huge differences in the developed software and its output.