# TED Community » Andrew Presnell

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• #### A comment onConversation: How do we prove an answer

Feb 17 2013: Michael Chidester, for some reason, I'm not able to reply to your statement.

It is a contradiction for the cat to be alive and not alive at the same time and same respect. To say that logic can prove contradictions are true is self referentially absurd.

With Schrodinger's cat, we do not know whether the cat is alive or isn't alive. To say that it is both is not only a contradiction, but unjustified. Consider the quote below:

"The observer cannot know whether or not an atom of the substance has decayed, and consequently, cannot know whether the vial has been broken, the hydrocyanic acid released, and the cat killed. Since we cannot know, according to quantum law, the cat is both dead and alive." http://whatis.techtarget.com/definition/Schrodingers-cat

The author's statement "Since we cannot know, according to quantum law, the cat is both dead and alive". This doesn't make sense. Indeed, we know that either the cat is either alive or not alive, but it isn't both. What justification is there to say it is either a or b, therefore a and b?

Feb 17 2013: Bahram,

If the universe was easily searchable, then I think you could conclude that it must be in the box. The problem is that the universe is vast. But even still, if you looked in the box for the ball and saw that it wasn't there, it would be a contradiction to affirm that the ball is in the box at the same time as you saw that it wasn't. Contradictions affirm that a is a and non-a at the same time and same respect. So it would be a contradiction to affirm that some ball has the quality of being in some box, while at the same time not having the quality of being in that same box.

Feb 16 2013: The law of non contradiction is: "a cannot be both a and non-a at the same time and same respect".

A water molecule is always in the form of a solid, liquid or gas at any one time, but never a conjunction of any two or three at the same time.

Does that make sense?
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#### A comment onConversation: How do we prove an answer

Feb 7 2013: You prove something by showing its contradiction is not possible. Watch some Sherlock Holmes.

“Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.”

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