The three foremost attitudes to have in scientific inquiry are empiricism, rationalism and skepticism. They all have to do with approaching difficult problems with a particular thought and reasoning pattern. Scientific inquiry relies on dealing with facts, logical reasoning and the constant search for new knowledge.
Empiricism is the reliance on facts and measurement. Empiric evidence is evidence that is experienced by the five senses and, therefore, can be repeated and experienced by multiple people. One of the requirements for a statement or set of results to be accepted by the scientific community is that a test have repeatable circumstances and results.
Rationalism is the practice of employing logical thought processes to understand the world. Logical thought goes hand in hand with empiricism, using facts to create deductive reasoning. One chain of deductive reasoning follows that if circumstance A is in place, result B occurs. A is true; therefore B is also true. Rationalism attempts to set aside emotional and wishful thinking, focusing only on the facts at hand.
Skepticism is the ability to question conclusions. Science breaks new ground all the time, and some previously accepted facts come into question. Skepticism allows scientists to change beliefs in the face of new evidence rather than cling to older beliefs.