Neuroscience and Free Will

neuroscienceincollege:

Neuroscience and Free Will

The video is about an experiment implies that our conscious decision is a very secondary thing to our brain activity.  The experimenters knew 6 seconds before the person would make a decision of choosing left or right.  Your consciousness is your brain activity (there is no free will because it is how your brain will react to a certain situation), meaning your decision is inevitable.

I do not necessarily agree with this argument because it does not deal with chance.  What if your brain activity also did not know what it was going to choose (even if it was 6 seconds before) but then by chance the brain activity told you to choose a certain thing (left or right for example)?