These are scientifically unsubstantiated claims but to claim that they are impossible is to go beyond the scope of the current science. We have a default stance on this, the 'null hypothesis' that states that these are not possible, a hypothesis which we have thus far failed to reject. This is not the same as saying that we've proven the null hypothesis to be true, we never really prove the null when we do hypothesis testing - we either reject it, or default back to it.
How can you know that mind control is impossible? If you were truly capable of it, would you advertise it? I know I wouldn't, unless I had a burning desire to end up in a government lab somewhere, which I don't.
Real science always rests on a backdrop of agnosticism, which people often forget and get caught up in emotionally charged ridicule.
But all that aside, it's not really about believing or not believing in whatever the claims are. These disciplines are all based on the 'doing' aspect - you do it, and if you feel the slow transformation of your character, then great. Whether or not you become a pyromancer is actually not important, most of these disciplines actually discourage these things even though they believe in them. Their stance is that different strange abilities may come and go but clinging to them is more destructive to progress than anything.
But all that aside, it's not really about believing or not believing in whatever the claims are. These disciplines are all based on the 'doing' aspect - you do it, and if you feel the slow transformation of your character, then great. Whether or not you become a pyromancer is actually not important, most of these disciplines actually discourage these things even though they believe in them. Their stance is that different strange abilities may come and go but clinging to them is more destructive to progress than anything.