If you are around teenagers, you will often hear them use an expression like "I just don't see what's wrong with...", whether it is an economic issue you are discussing, such as the raising of the minimum wage, or a very subtle moral issue, etc. The tone of the expression "I don't see what's wrong with..." more often than not reveals it as a kind of argument, as if to suggest that "there can't be anything wrong with..., because if there were, I would see it."
The problem with the expression so employed is that it is a slight variation on WYSIATI (What You See Is All There Is), a bias at the root of the availability heuristic. We tend to make inferences on the basis of very scanty but readily available evidence, and we tend not to give serious consideration of the possibility that what we see is not all there is, that reality is much larger than what has hitherto been made available to us.
Of course we "don't see what's wrong with..." That is a normal state of affairs; we don't see what's wrong with it (and many other things) until we actually do see what's wrong with it - and there are a number of ways to come to see something we simply did not see before. All throughout our lives we continue to discover things about issues, principles, people and places that we never dreamed we would. Life is full of surprises.
There's a vast space of reality that we don't see, and there are layers of reality that will remain forever beyond the purview of our minds and our ability to express in language. But most importantly, there are layers of reality that will only be uncovered under very specific conditions, and it may take years to acquire them. Many of these conditions depend on asking the right questions as a result of having to solve certain problems, and being positioned in a way that permits one to see what would otherwise be very difficult to see, and knowing the right people, finding oneself in the right circumstances, acquiring different interests, etc.
No conclusion about the truth of moral or other matters can be drawn from "I can't see what's wrong with..." For I cannot understand what it is like to be a bat or a snake, but I cannot for that reason conclude that there is nothing that it is like to be a bat or a snake. Moreover, I don't know what it is like to be sexually abused, clinically depressed and suicidal; but it is arrogance to infer that there is nothing that it is like to be "clinically depressed" and to then proceed to argue that such people only experience a low grade sadness that most of us experience periodically, and that all they need are some simple tools to help them cope.
"I don't see what's wrong with..." is an expression we often hear among the young because they simply do not have enough experience in being wrong to have become more acutely aware of their own limitations. But the expression and the rather dogmatic attitude behind it are found all too frequently in adults - who should know better. Those who are wont to declare "I just don't see..." stop investigating, or limit their investigation to a comfortable mode of thinking and a familiar angle, which permits them to go on within the complacency of being certain and right.
Take a contemporary issue. I might assert that I don't see what's wrong with the status quo in the Church regarding LGTBQ issues. However, I also don't know what it is like to be gay, or what it is like to have a male body and feel that I am a woman, or have a female body and feel that I am a man; I don't know what it is like to be a teenager who hears his friends talk about desires that he simply does not have, such as desire for the opposite sex. I can imagine partially, by comparing it to a similar experience, i.e., the isolation I experience when I learn that my friends are all going off to this or that place for the summer while I have to stay home, because we cannot afford to travel overseas; but something tells me that this does not quite carry the same weight as the former.
I can imagine what it is like to be terrified of the prospect of spending the rest of my life alone, and to have finally met someone who alleviates that fear, who is wonderful to be around. But when I do so, I imagine that this person is of the opposite sex. Imagine what it would be like to find no reprieve from loneliness in a person of the opposite sex, but only in a person of the same sex. Imagine further that you are a member of a Church that, for the most part, does not quite understand these desires and fears as those who have them might understand them, that avoids looking at the issues from the perspective of a person who has them or that limits the discussion to a level that is rather abstract, detached, and moral. Let's try to imagine what it would be like to be told that you must resign yourself to living alone for the rest of your life, but you have to imagine that as someone who lacks the theological and moral understanding, the spirituality, and emotional stability that you possess .
On the other hand, I might also be a person who does not see what all the moral fuss is about. I would say most people are in this category, and rarely do such people not overstate their case when discussing the issues - that is, "I don't see what's wrong with ...", delivered with a lot of aggression. We ought to keep in mind, however, that there might be valuable insights just around the corner, principles and their implications that I cannot at this time see, but which others can; after all, there are people who have spent their lives thinking about these things, just as there are people who have spent a good part of their lives learning how to fly a commercial aircraft or master a musical instrument. I can't see what's so difficult about flying a 747 or playing the piano, until I actually try to do so, which I have not done as of yet; all I have to go on is what I have seen, and pilots and pianists make it look so easy.
This is a fundamental problem with the world we are living in, and it is an epistemological problem. From a theological standpoint, I would say it is an effect of that wound of Original sin that is traditionally referred to as concupiscence (of the flesh, of the eyes, and the pride of life), which includes the lazy tendency to make our own purview the measure of what is true, rather than to look to something larger (i.e., reality) as the measure. And so there is little dialogue, little discussion, a great deal of fear, anger, smirking and ridicule, not to mention a large pool of ignorance.