My take is that engineering is essentially the use of predictive models to solve design problems. I think the general trend is that the more accurate and universally accepted the models are, the more ‘engineery’ a particular discipline is. EEs use models of circuits and devices. ChemEs use models of chemical reactions. MechEs use models based on physics. Financial engineers use models of options pricing, etc. Optical engineers use optics.
So, similarly, SWEs are engineers to the extent that they use widely accepted models to solve design problems. People building compilers, databases, or OS schedulers might be called engineers, because there are relatively well accepted (but evolving) models of the performance and capabilities of those things—-although those models are perhaps less universally accepted than say, Newton’s laws. Hacking, on the other hand, is not engineering, because it is not backed by something like a well-understood model. It therefore tends to command less respect, as the output of such activity is less certain—since there is no good predictive model to judge whether that activity will achieve the goal.
The model aspect is a good addition, because that's one of the things that differentiates engineers from pure scientists, or mathematicians. Engineers design to the model, which in some cases may not represent reality with complete accuracy, but will in those cases be much easier to work with. So long as that model has a demonstrated track-record of producing good results, and the same assumptions it makes have been proven valid for the current design, then it's usually good enough for design purposes.
So, similarly, SWEs are engineers to the extent that they use widely accepted models to solve design problems. People building compilers, databases, or OS schedulers might be called engineers, because there are relatively well accepted (but evolving) models of the performance and capabilities of those things—-although those models are perhaps less universally accepted than say, Newton’s laws. Hacking, on the other hand, is not engineering, because it is not backed by something like a well-understood model. It therefore tends to command less respect, as the output of such activity is less certain—since there is no good predictive model to judge whether that activity will achieve the goal.