Should we purchase used/old engineering books? Should we even borrow a book from the library and use it in an analysis?
Should we use software at all? Free or purchased?
The ethics are not so obvious, but the way I see it, professionals owe absolutely nothing to the software industry. We do, however, owe it to ourselves to appreciate and purchase the old textbooks and if we cannot afford to purchase them we should take advantage of the local library or rummage sales.
On the issue of software: software producers make money selling software, not using it. And once you're purchased their product, unless you upgrade, they'll make no money off you. Personally, I consider it unethical for software companies to sell a product that "may" have a few bugs in it, but they'll fix 'em on the next upgrade...
Concerning free software, if the tools are available, why not use them? Besides, if you make a mistake, the lawyers aren't going to sue the software company, they're going to sue you, and if you say, in court, "...the computer said it was OK..." you're going to lose your license and become a laughingstock for a while.
There are a lot of very nice spreadsheets, MathCAD, HyperCard and other free engineering analyses software that have been around for years and year. The authors ask for nothing in return, thus, what is the issue? Is it ethical to cut corners using software at all? Is it ethical for software companies to extort upgrades/license fees out of companies?
Is it ethical for software companies to sell the proverbial "bill of goods" with poor documentation, no customer service, etc.?
Is it ethical to use the free "works" programs that came with the computer or should we trash them and purchase a more (sometimes very) expensive program?
My opinion is that it is ethical to use the best tools you can afford to do the job. If one is in "learning" mode or happens to be a student, money is hard to come by, so you use what you can. If you're a professional being paid, you use what the company has. If you're a consultant, you use what's best for you and your customer. For example, if a job requires that you provide electronic drawings in Microstation format, and your office is an AutoCAD shop, you DO NOT give the customer .dxf files...