You call yourself a scientist?

Politicians and ideologues have always sought to portray their ideas as being "scientific". The word is bandied around like there's no tomorrow. So what, if anything, do, or should, people who describe themselves as 'scientists' have in common?

There are certain things which anybody who wants to consider themself a scientist is supposed to do. Scientists are supposed to observe the real world, and formulate hypotheses about how it might work. They should then test these hypotheses using all the analytic tools they have access to (observing through stethoscopes, x-rays, and analysing their findings with mathematics, especially statistics). Scientists are supposed to create models (either conceptual or physical ones) to explain their observations, and to revise and refine these models based upon the evidence that they gather and pain-stakingly control. Obviously, scientific hypotheses are actually TRUE or FALSE in some sense - there either was a big bang or not. But scientists do not propose or execute experiments with the aim of revealing some grand "truth", but in terms of the increasingly accurate predictive and explanatory power of these models and the evidential support of their hypotheses.

The heuristic maxim that is the backbone of science is Occam's Razor.
"Numquam ponenda est pluralitas sine necessitate ::::: Plurality ought never be posed without necessity". Galvani Volta thought the electricity in the nerves of living creatures was of a different nature to the electricity that ran machines or stretched between the clouds. Mistake. The introduction of an extra category was unnecessary, entirely superfluous, and did not fit any observations at hand but was based on a bias, a prejudice (So must many of our beliefs today be, but we know what is wrong, and it is hypothesis that does not match belief, and we may weed out wrong hypotheses). Newton made no such mistake. He realised that the SAME, UNIVERSAL force made his apple fall from the tree to the ground as did keep the moon in orbit of the Earth. Positing a redundant extra force to move the moon was not only no longer necessary to explain what was observable, it was entirely absurd.

As scientists rationally attempting to evaluate what we see / what we see our equipment registers, we look to the most simple explanation which best fits in with the body of evidence that we have from all of the scientific fields of inquiry. When we propose an explanatory entity, this entity MUST EXPLAIN MORE, through its introduction, than it would render unexplainable and unpredictable, than it would introduce logical contradiction or redundancy.
As an example - to a scientist, it is possible, but ENTIRELY IRRATIONAL, to believe that there is an alien hidden by an energy field in this room which does X and Y that I can't explain. All of our observations seem to indicate that there is no alien presence changing anything in this room, so to propose that there was one would raise many more questions than it would solve. You go with the most simple explanation for what you observe. Not for what you want to believe. Not for what is possible. Not for which there is no evidence AGAINST. Not for what would be "cool" or more interesting or would make you want to pray. It may be dull, but have the courage to apprehend the world as we observe it. The flickering lights are more probably caused by current fluctuations, the graphical aberrations on my monitor caused by the age of my video card etc, the sound in the roof by a possum. The new entity or force should not raise more questions, or be redundant somehow. We should always doubt 'miracles', not only because the idea of a miracle is logically impossible, but because we peform 'miracles' by standards of old, and we now understand that there's no such thing.

If a person reveals that they take seriously the possibility that ghosts exist, this is plainly not the opinion of a scientist, or rather, it is not the scientist in that person talking. Now, it may be that ghosts or the afterlife DO exist, in some sense (though I don't believe this). There is a HUGE DIFFERENCE between acknowledging the possibility of something existing which seems extremely unlikely and actually entertaining the idea as part of your belief system. Any self-respecting scientist must declare that they almost certainly do not exist, given the complete lack of evidence for them. And no scientist can admit of the existence of non-material objects or objects which cannot be observed or described, precisely because they cannot be observed or described. So the scientist speaking needs to encode such a belief in to an hypothesis of some kind! Granted, there is not always consensus in the scientific community, but it certainly does emerge on well-studied issues, at least until new evidence crops up. Scientists should know as much about the problems with human perception, with human emotion, with the biases of human intuition, and with our logical and intellectual limitations as they do know about the problems of measurement.
Likewise, it may be that there is a God. But no scientist can say that his or her belief that there is a God is at all scientifically reasonable. No true scientist thinks in terms of "God". There is simply no observation that can be made which justifies considering such an object or using it to explain the mechanisms of nature. The idea of "God" has zero explanatory power, raises more questions that it answers, and is entirely redudant - other things explain more than adequately what "God" is supposed to explain. If you are a scientist, you are a materialist, and that's that. If you're a scientist and you believe in a God of some kind, you have not just seriously compromised your scientific integrity and credibility in a number of ways. You have selectively rejected the input of the scientific method on a number of questions and embraced some combination of mysticism, dogma, faith and revelation as the tools by which to gain knowledge on these questions or structure your life experiences. I'm not saying you're wrong for believing in God. You are just not a scientist in the truest, most consistent sense. You may occupy a scientific post and improve man's scientific knowledge but you lapse in to unscientific thinking on certain questions. You may be very very intelligent in many ways. But you are just not consistently using the thought-tools which have taken us out of the pre-industrialised, primitive world. Like everybody, I suppose, you are just not thinking scientifically at all moments. Nothing necessarily 'wrong' with this, we're free to believe what we want and think like we want. Just be aware that's what you're doing.

A reasonable scientist would do well to be skeptical of a variety of many other things. If human telepathy were possible, why is it that nobody who claims to possess these powers has ever been able to demonstrate them in a laboratory, under controlled settings? Why is it that there is absolutely no evidence for the existence of aliens? For anything supernatural? Of human prophets? Of humans with healing powers? Of ESP, spoon-bending, triangles in which people disappear? Of God, the Devil, of the tooth fairy? Why is that there is evidence for evolution and none for "intelligent design"?
Scientists, either try to consistently think scientifically, or acknowledge that many of your beliefs are deeply unscientific and that you're happy with not subjecting all of your beliefs (maybe most of them) to the scrutiny of scientific methods.