Probably one of the more ridiculous things I've read on this forum.
Economics is like any other scientific field, though less mature than many fields as it's been around for a much shorter duration and is much more difficult to test hypotheses.
The principles of modern medicine go back millenia. Likewise with astronomy, physics, math, biology, etc. Economics -- while there were some writings as far back as ancient Greece -- wasn't seriously embraced as a field of study until the middle ages, and the bulk of economic writing is from just the past few centuries. And the number of test cases for other fields measure in the millions, while economics can't easily be modeled/tested on a large scale outside of real world implementation.
Economists are continually gathering data, testing hypotheses, modeling and making predictions. When those predictions pan out, they are given more weight and continued to be tested. When they don't, they're thrown out and we start over. No different than any scientific endeavor.
To compare that to palm readers is simply ludicrous.
That said, I guess I can understand how a lack of education in the field can lead someone to that belief.