The existence or non-existence of Absolute Certainty cannot be proven.

I think you have claimed victory rather too early, as my concession to your 'brain in a vat' idea does not weaken my argument in the slightest. Furthermore, your semantic tricks do nothing to weaken the law of identity.To my knowledge, true nothingness does not exist in this world because we must consider energy (and so matter), space and time. Clearly a vacuum still has space and time. Regarding your first example, A single photon can not be observed to be both a wave and a particle simultaenously. [Pro's source]. Therefore, your argument should follow: Photon A is acting as a particle Photon B is acting as a wave What is acting as a wave may not be acting as a particle simultaenously. Therefore Photon A is not, at this moment, the same as Photon B. I do not see that the law of identity has been breached. You may as well have argued that 'Man = Man', yet Man A is a murderer and Man B is not, and concluded from this that the law of identity has been breached. Regarding your second example, Virtual particles do not occur from nothing; the term 'nothing' is being used to indicate (I believe) no mass and no energy. This is not nothing, as there is still time, space and quantum fluctuation. If there was nothing, what would be fluctuating? True nothingness cannot fluctuate otherwise it would not be true nothingness, it would merely be something that appeared to closely resemble nothing. Regarding 'man-made logic', Sometimes, we do not need experience to know what is true. It is true, for example, that all bachelors are unmarried. We only need to know the definition of 'a bachelor' to know that this is the case. This is not an assumption, but rather it is a truth derived from pure reason. You mistakenly assume that experience has anything to do with it. Wittgenstein would say to you that in doubting logic, you have attempted to utilise logic: when you declare that logic 'may be doubted', you have used a corrupted idea of logic to establish that logic may be false. Logic is nothing more than a system of determining what is true, what is false, and what may be. If you declare that the law of identity is false, then you declare that it is not logical. If you declare that logic is false, then you have declared that it is not logical. There we find that your position is untenable, for to use an argument to prove that logic is false is to attempt to use an experiment to prove that scientific method is flawed. If you wish to prove that the law of identity is false, you must use something other than human uncertainty to acccomplish that, for your refutation of 'a raven is a raven' hinged upon the idea that humans may be unable to determine that what is a raven is a raven, and you were not able to show that what is defined as a raven is not what is defined as a raven, which is necessary to your case. I conclude this round by again challenging my opponent to show that my argument describing how 'something must be something' is false, without reference to invalid arguments or incorrect definitions of 'nothing'. Whether this reality is not 'true reality' is irrelevant, as it is clear from my very ability to think that there is something, and this truth will not change.