How can you know that meditating isn't selfish? Perhaps 'selfish' isn't the right word for it as the 'self' is not the goal. But if you define the 'self' as your inner core/soul is it still possible to meditate selfish? If so how to know this and how to prevent this? How to distinguish between 'good' and 'bad' ('achieved') enlightement?
But if you define the 'self' as your inner core/soul is it still possible to meditate selfish?


One purpose of meditation is to deepen your understanding for anatta, non-self. Meditating as intended, one develops a different view on the self than the definition above, for instance.


  If so how to know this and how to prevent this?


On one hand - among other things - one needs to familiarize oneself with the theoretical concepts of:


the twelve nidanas, for general understanding on how wrong view leads to suffering
bhava tanha, for specific understanding of wrong striving for defining a self
the five skandhas, for right understanding of a wholesome alternative to defining a self


On the other hand, to prevent that our insights stays a mere theoretical product, we must also examine how these phenomena plays out in real life, with the aid of:


right mindfulness, in order to recognize when we falsely identify with a certain concept of self
right effort, to explore new habits allowing us to break the patterns creating more suffering, and to develop habits conducive to the cessation of suffering