As mentioned several times before "best play" means playing any move which does not change the result of the game. Thus since the starting position is a draw if either White or Black makes a move which would lose the game--he/she is not using "best play"
There is a ton of evidence that chess is a draw. Chess is far too complex to "solve" but the very best
players know and assume chess is a draw when neither side makes an error.
Nothing is 100% certain. But the best players see the ton of evidence.
The answer remains hypothetical. The simplest test of the proposition is for the claimant to attempt to force a draw in practical play. No one has found an irrefutable method for doing so. Hence, the qualifier “with best play” is invoked to account for the failure. However, Best play remains hazily defined from the starting position.
There is good reason to believe that chess is a draw with best play, but the truth of the hypothesis remains speculative.
I probably wouldn't use the term hazily. I would probably say foggy, or at least cloudy. Don't mean to rain on Ponzs parade, but I think term "best play" does indeed need more sunshine.
Maybe "undefined". Is 1.e4 superior to 1.d4? Can the French Defense be refuted? Is the Scandinavian Opening a weak choice?