Does MN 60 contradict SN 12.15? If so, why is it so? SN 12:15 Kaccayanagotta Sutta states: 


  By &amp; large, Kaccayana, this world is supported by (takes as its object) a polarity, that of existence &amp; non-existence. But when
  one sees the origination of the world as it actually is with right
  discernment, 'non-existence' with reference to the world does not
  occur to one. When one sees the cessation of the world as it actually
  is with right discernment, 'existence (atthitañceva)' with reference to the world
  does not occur to one. 'Everything exists': That is one extreme.
  'Everything doesn't exist': That is a second extreme. It's to this
  extent, Kaccayana, that there is right view.


MN 60 Apannaka Sutta states: 


  ...this venerable person is still criticized in the here-&amp;-now by the observant as a person of bad habits &amp; wrong view: one who holds to a
  doctrine of non-existence.'
  
  ...this venerable person is still praised in the here-&amp;-now by the observant as a person of good habits &amp; right view: one who holds to a
  doctrine of existence (atthikavādo).'


My reading of these two suttas gives an impression of a contradiction. MN 60 appears to state the 'doctrine of existence' ('atthikavādo') is right view. But SN 12.15 appears to state the 'view of existence' ('atthitañceva') is wrong view. 

Is this a contradiction? If so, what is the cause, what is the reason, for this?
SN 12.15 says that "everything exists" and "everything doesn't exist" are opposite extremes and are both wrong view.

I guess there are different problems with each view: e.g. "everything exists" implies attachment and ignores conditioned/composite nature of everything; whereas "everything doesn't exist" implies nihilism and amorality.

I think that MN 60 concentrates its argument on one aspect, i.e. that the view that "nothing exists" leads to amorality:


  it can be expected that, shunning these three skillful activities — good bodily conduct, good verbal conduct, good mental conduct — they will adopt &amp; practice these three unskillful activities: bad bodily conduct, bad verbal conduct, bad mental conduct. Why is that? Because those venerable contemplatives &amp; brahmans do not see, in unskillful activities, the drawbacks, the degradation, and the defilement; nor in skillful activities the rewards of renunciation, resembling cleansing


For that reason, "everything exists" is the relatively skillful view.

Incidentally I think that people sometimes talk about a "two truths" doctrine, i.e. that "conventionally things exist but ultimately nothing exists". Another way to express the "conventional truth (or relative truth) versus ultimate truth" duality is to call conventional "skillful" or "skillful means".