And the MBTI doesn't imply or assume axes. A type (e.g. INFP) is a label for your cognitive processes.

e.g. INFP leads with a primary Introverted Feeling (judging), an auxiliary Extroverted Intuition (perceiving), then Introverted Sensing, and finally Extroverted Feeling.

Some of the better tests will help identify these cognitive processes and then attempt to find the best fitting type based on them. You can read more about the cognitive functions here: http://www.cognitiveprocesses.com/Cognitive-Functions/index....

It's too bad that so many people see the types as diametrically opposed (e.g. Feeling vs Thinking -- you do both!)