Free Will

Are you really free to chose what to do?

Science tells us that all effects have causes.  Is this right?  The fact that I have just typed this sentence (the effect) was caused by a synaptic response in my brain.  In turn, that was caused by molecule A being affected by dendrite B (or whatever), and so on, back to the 'big bang'.   There simply cannot be any effect without there having been a pre-existing and relevant 'cause'.  If that is right, then we seem to have no power to chose what we are going to do.  The 'present' we have is the only possible 'present'.  The past we have is the only possible past.  Therefore, the future as it will be in one minute's time would seem to be the only possible future there is.  And so, any person committing a criminal offence can just say 'well, it was inevitable - from the dawn of time, each cause has given rise to a particular effect, that has itself been a cause of another effect, and so on, and so my (criminal) act was just bound to happen - not my fault - blame destiny'.

Hmm...

Or is there something special about human agency?  Animals, and the external world seem to have to comply with the laws of stimulus and response - stimulus 'A' happens, causing response 'B'.  Humans are different - between stimulus and response, we have free will.  We can choose whether to react this way as opposed to that way.  

Really?  What do you think?!