Carol, I think charlatan carries a negative connotation that has no place in this discussion. I would agree to the use of the term as it relates to a specific individual such as Uri Geller. The people I am referring to as pseudoscientists are those who truly believe in what they are doing and could never conceive of using it for profit only. These people truly believe they are helping people.

I have a dear friend, my former voice teacher, who falls into this classification. She does voice analysis and reads auras, locates power centers in the earth and all that other stuff. We love each other as only the closest friends can but we also understand each other's position on this subject. She knows she will never convince me to change my mind without an accurate unbiased experiment and I know that she will never change her mind. Null set. We cancel each other out and maintain a healthy friendship.

The charlatan, on the other hand sees the believers as sheep ready for the clippers. No device is too low to use to take their money and explain away why the result was not as intended.

I'll let Bill address the subject of logic. He has done a great job so far.