Claw Marks

I learned this thought from Richard Boenninghausen at the General Electric Computer Department in the 1960's.  Fundamentally, the idea is:

When considering a new idea or invention, always determine whether it has claw marks on it.

By claw marks I mean that the item has been tried by others before, and they have had a go at it without success.  If the item hasn't been tried before it is always worth trying -- you don't know what will happen and you may succeed with only minor effort.  Only minor claw marks might make you decide to try it despite previous attempts, on the theory that the effort wasn't extensive and may have missed something.  If there are lots of claw marks, then the idea has really been tried/exercised by others and you know it is difficult, at the very least, and may be impossible. 

The classic case of an idea with claw marks all over it is the problem of batteries for electric cars.  Untold amounts of money have been spent by many organizations on this problem over several decades, with limited success.  In this specific case, however, a pressing need motivated continued massive effort and new solutions finally did emerge, but the pain and expenditure getting to this point (2010) were very considerable.

In my experience, people do not carefully distinguish these several cases and end up wasting resources or naively believing that simple solutions will be found to difficult problems.   Of course, wholly new approaches can change this evaluation, but the philosophy enunciated here is a good place to start in your considerations.