I state here on my Web site that the key person whom I am called to serve through my writing, coaching and speaking vocation is as follows:
The critically-thinking professional seeking deeper fulfillment—spiritually, relationally, intellectually and emotionally.
So what exactly is a “critical-thinker,” and do I claim to be one? The first part of this question is easier to answer than the last; for the last part I can simply offer, “I hope I am,” knowing very well that a decade from now I will have deeper insights and more self-awareness across the board than I possess right now. 
Going back to the first part, then…often it is much easier to define something in terms of what it is not. For example, a critical thinker does not constantly look to others to help he or she decide what to do. A critical thinker does not simply go with a herd mentality. He or she does not buy what the press or popular culture communicates hook, line and sinker. This person does not just think about what they want right now, or define themselves or others by material possessions or goods, or care only for their own welfare. Imagine the opposite of a critical thinker, and you can easily think of George Costanza from Seinfeld; Bart Simpson; or most of the cast of Desperate Housewives.
What this person does do, then, is captured well in the opening of the current Wikipedia entry (http://en.wikipedia.org/wiki/Critical_thinking):
Critical thinking is assumed to be the purposeful and reflective judgment about what to believe or what to do in response to observations, experience, verbal or written expressions, or arguments. Critical thinking may involve determining the meaning and significance of what is observed or expressed, or, concerning a given inference or argument, determining whether there is adequate justification to accept the conclusion as true. Hence, Fisher & Scriven define critical thinking as “Skilled, active, interpretation and evaluation of observations, communications, information, and argumentation.” Parker & Moore define it more narrowly as the careful, deliberate determination of whether one should accept, reject, or suspend judgment about a claim and the degree of confidence with which one accepts or rejects it.
Critical thinking gives due consideration to the evidence, the context of judgment, the relevant criteria for making the judgment well, the applicable methods or techniques for forming the judgment, and the applicable theoretical constructs for understanding the nature of the problem and the question at hand. Critical thinking employs not only logic but broad intellectual criteria such as clarity, credibility, accuracy, precision, relevance, depth, breadth, significance and fairness.
In contemporary usage “critical” has the connotation of expressing disapproval, which is not always true of critical thinking. A critical evaluation of an argument, for example, might conclude that it is valid.
Several key words jump out at me here. Purposeful. Reflective. Meaning. Significance. Active. Consideration. When I envision a critical thinker, I picture someone with a sense of urgency about their life, someone who is willing to peel back the layers to see what is there, to seek first to understand before trying to be understood.
Years ago I covered county and city government meetings for a local newspaper in Central Florida. Usually the same pack of gadflies attended these sessions, representing only a minute percentile of the voting population. These folks usually came armed with strong opinions, and I would often shake my head when one of them would approach the microphone and rattle their saber with embellished emotion and the clones in the audience would nod their heads, cheer or clap. I would say to myself, “Think, people! Think!” And wished I could put that into print.
Perhaps part of what fuels my frustration when I observe a lack of critical thinking is the potential for injustice. I've simply seen too many people taken advantage of because they were being spun or marketed due to failure to engage their critical thinking faculties. Sometimes in life I have been the person who was spun. A large number of people are at risk, because it is the easier road to not ask the hard questions or challenge the establishment and simply believe/do as you are told. Great atrocities have occurred across world history due to a lack of critical thinking among the masses, Nazi Germany being just one contemporary example, slavery a more distant one along with lack of women's voting rights.
My passion is to reach the people willing to take the road less traveled, those motivated to pass through the more narrow gate. We learn much from each other, us evolving–but not yet arrived–critical thinkers.
Finally, what do I mean by “professional?” Frankly, the clients to whom I can best relate tend to be immersed in a particular discipline or two. In most cases this involves them having an educated background, but not necessarily. Ultimately, for me the “critically-thinking professional” is anyone who purposefully embraces a vocation, that word which Frederick Buechner aptly describes as the place where one's deep gladness and the world's deep need collide with one another.
And what an impactful sound that makes.