The term “inferiority complex” was coined by psychologist Alfred Adler. The idea is that each individual is born with a weakness, this may be physical or not. For example, someone might be born with bad vision, hearing, or locomotion. These children tend to develop insecurities about these shortcomings (organ deficiencies) that they deliberately choose to spend their time doing things to make up for them. If they have a hearing problem, they tend to become musical. If they have bad eyesight, they become obsessed with visual stimuli.
In the same way, the birth order of a child can result in an inferiority complex. This is not true for the oldest child but can be true for the second child or the youngest child. The second child will feel that they are in competition with their older sibling and will strive to outperform them, while the youngest sibling, in an effort to prove that they are significant, will work the hardest to become the most competent member of their family. In Biblical and ancient stories, the last born child is often portrayed as the savior of the family.
But what Adler is insinuating is not that any of these people are destined to have an inferiority complex. They may react in this way or they may not, and this will, to a certain extent, depend on their upbringing, on whether their parents endowed them with feelings of self worth or not. But even if they were not given the best treatment as children, the individual, according to Adler, is always free to determine their own destiny. If they choose to, they can overcome their past conditioning and assume a more healthy attitude towards life, to be less aggressive, self-centered, competitive, and envious towards others, to be more friendly, and to enjoy the accomplishments of others.
This is not to say that an inferiority complex is inherently bad. Without a feeling of inferiority, people will never pursue superior goals and ideals, they will never try to improve themselves. The inferiority complex is only pathological when pushed to the extreme.
For Adler, social harmony is the highest good and the danger that afflicts each individual, is to feel that they are not enough, that they must constantly battle with others to deserve respect, even after they have attained a high level of respect. Consider the professional musician who is relentlessly unsatisfied, despite achieving numerous awards and prizes. The pathology is when nothing ever seems to be enough.
If these people are inflicted with an inferiority of complex, a low self worth, they may be inhibit their own growth, be less aggressive, and more defensive, they will turn their aggression inwards and will become recluse. They will avoid social contact and shun society.
These reactions are two different ways of responding to a feeling of inferiority in the world, but in either case, the individual will be miserable. They may attain financial success, they may become popular, but they will never be content with who they are. They will constantly be in pain and in agony.
The ideal is to apply yourself and work hard on your goals, but not to take life too seriously, for nothing in the end is all that important.