Ok, this is a topic which I have some thoughts on. So I will lay down my personal opinions on who is qualified to be a critic.
First of all, who or what is a "critic". This itself has many variations in definitions, such as
#1 One who engages in analysis and interpretation of works of art
#2 One who expresses a reasoned/value judgement
#3 One who finds faults or makes harsh and unfair judgements.
For the purpose of this thread, I would think that the appropriate definition and its variations would be #1 and #2. I think any sensible person here would object to the kind of critics in definition #3.
And I would add a clause that the purpose of a critic to analyse/interpret and give a value judgement would be to help the artist to improve what he wishes to improve.
NOTE THAT THE PURPOSE OF A CRITIQUE IS NOT TO IMPOSE ONE'S (THE CRITIC'S OWN) ESTHETICS, BUT TO HELP THE OTHER ALONG HIS CHOSEN PATH.
This is the reason why in critiques circles, the opening question is often "what are you trying to say or portray?". Although I personally hate this question, it does help one to analyse and give approrpiate comments.
Note that this definition of a critic effectively excludes statements such as "I like it", " I do not like it", with their various variations in both gentlemanly and or bas***dly presentations. These are mere emotive responses to the image. They have their role. But they do not constitute "critiques"
Now who is qualified to be a critic?
Potentially - ANYBODY.
However we must not be deluded to think that anybody can give a meaningful critique. Ideally, one should possess the attributes of keen and developed artistic sense, technical competence, clarity of thought, and command of language to put the thoughts across. But I suspect that not many people possess these attributes in sufficient amount. I can accept that. But then I will also place into suspect the quality of the critiques.
Would I like to receive critiques from a non-photographer? Potentially no. They may or may not be artistically inclined. They may be able to discuss with me the esthetics merits on my images. But they will not have the technical expertise to advice me on how to make my images better. To tell me my image sucks, but do not show me how to improve my image is at best sloopy. At worse, hypocrisy.
But I do look to non-photographers for their emotive responses to my images.
There are exceptions of course of nonphotographers who are great photography critics. One who comes to mind is John Szarkowski.
Catchlights made some reference to giving critiques on food. He is right that I do not need to be a cook to appreciate which satay is good. However, I can only say that this satay is not to my taste, or that satay is to my taste. When I tell the cook that I do not like his satay, I am merely telling him how my tastebuds react to his satay. I do not give a value judgement, or advise him how to make his satay better. Some may feel that this constitute a "critique". I will not object vehemently to this. But I submit that this is a very low level "critique".
Must the critic be a photographer? As mentioned above, not necessarily. There are those non-photographers who give great critiques. But the number of competent critics from practicing photographers far, far outnumber non-photographers. For very obvious reasons.
Not all photographers make good critics. Just like not all good footballers make good coaches. In this subforum, one sees a lot of comments from "professionals" making their own values the standards by which others should follow. Example: the thread on "Yuki". They forgot, or they might not even know that some are not interested to make images for clients or profits. So such critiques are totally misdirected and irrelevant. Giving critiques to a fellow photographer who aspires to be a wedding photographer will be very different from giving critiques to a fellow photographer who wants to make 'art" images.
So professional photographers may not be the best as critics, because they might have pigeoned themselves into a specific mindset over the years. But still, on the whole, I would value the opinions of photographers over nonphotographers.
So who are qualified, by the criteria laid down above?
I am certainly not. And I suspect that most are not. Does it mean that therefore we should not attempt to give critiques? Or course not!
But I hope that we can look at ourselves in the mirror, and ask if we really possess keen artistic sense. If we possess a clear analytical mind. If we are competent to show how, by word or example. If we are able to communicate clearly our thoughts.
And most importantly, if we really care.
This, I think is the most important. Even if we do not possess keen artistic sense. If we do not possess keen analytical minds. If we do not possess competent know how. If we are not in command of language abilities. We can still give critiques.
But we will know our place. The value of our critiques. We will be a lot less arrogant and dogmatic. And that qualifies us to give critiques right here in our beloved CS.