In principle, criticism is there to judge the merits and faults of something. Those being critical will then be assumed to have a good, informed judgment about the matter being criticized.
Praise on the other hand is there to express recognition, admiration, or reassurance. When sharing verbal praise people share a positive evaluation of someone else’s attributes or actions.
Both, in their respective ways, are there to sustain growth and learning.
Learning usually happens within an obscure process. The methods used for learning suggest a clean and well-designed path towards a set learning goal. They rarely describe the experience of learning. Learning is more of a long, cyclical, and windy process requiring our trust that it’ll eventually work out.
One way to shed light in the dark is praise when it helps see the progress made along the journey. The learning usually being more visible to outsiders than the person herself.
On that journey, it is criticism that will assist the learning process by easing the assessment of the things that went well and those that didn’t work out as expected. Without such a critical view it becomes pure luck to choose what to retry and how to adapt the trial.
Both praise and criticism can be used in a manipulative way. In the case of praise, it can be a way to reward a person whereas criticism can be used to shame others. Which means that they are being used to serve a different purpose than helping the person and her development.
This raises the interesting question as to why individuals rarely use self-criticism and self-praise to sustain their own growth.
Is it there to make sure that the reactions from others can only be better than what people are giving themselves through negative self-criticism? Is self-praise the assumption that one has to boat about oneself as no one else will step in and see one’s achievements?
Both indicate an attachment to receiving recognition from others as a means to develop oneself. It’s less the inability to see the reality of one’s own learning than the need to be seen by others.