Foundational as a basis for scientific claims
"The goal of reproducible research is to tie specific instructions to data analysis and experimental data so that scholarship can be recreated, better understood and verified." CRAN Task View on Reproducible Research
Crisis of confidence in results of data analysis due to lack of reproducibility.
Across time (running the same analysis again years later)
Across space (moving code from a desktop to a server, or between the systems of collaborators)
In R we do better than in many environments, but we don't do well enough.