This semester I taught Statics for the first time. The material isn’t very difficult. It’s the same concepts applied to different situations. I assign homework problem from the book as a way for the students to practice the skills and learn the material. However I’m finding that students have easy access to solutions from online resources. I don’t mind if they look at a solutions manual to help them understand how to do something. The homework is not worth many points in their total grade. However it seems the availability of the solutions is making them dependent. Most of the students can do the math and write the equations, however many don’t know where to start a problem without the solutions. They can’t go blind into a problem and solve it, and that’s killing them on exams.
So I think the true issue of solutions manuals is not they give the answers, but they acts like a safety blanket and make the students dependent on the existence of solutions. Perhaps the solutions reduces the anxiety of working the problem, knowing the answers are right there if you want to look. But in real life there are no solutions manuals. In your job no one will be able to tell you the answer. You have to to be able to work the problem and know if the answer is reasonable and looks correct.
So my suggestions for all students is to always do your homework blind first, without the solutions. Then once you’re done, you can go back and check your answers. Don’t jump immediately to the solutions at the first stumbling point. That creates a dependency and doesn’t teach you how to examine and solve the problem.