Hahaha the old "evil demon" idea by Descartes. Yes this is a very important claim. We could very well be in a simulation (or in a dream state) and there is no way we can prove otherwise because our senses (and all its information) are drawn from this world. It is possible that there is another reality that underlies this one, similar to how our current reality underlies the reality of a dream.
In Vaishnav Philosophy, this reality is true, but it is not the highest reality. All the concepts found here are not original, but rather a perverted form of the spiritual world, which is Sat Cid Ananda (eternal, conscious and blissful). The objects in this world are subject to decay by the influence of time, while in the spiritual world, they are eternal present. The objects in this world give us only finite joy, while the objects in the spiritual world give us increasing bliss. The objects in this world are not conscious, while in the spiritual world every atom is conscious. Just like the sun reflects itself in the water, this world is but a petty reflection of the spiritual world. Just like the concept of a car is found in a Mercedes, but not the other way around, this world is but a concept of the original one.
You may then ask, how can we, the conditioned beings, find information about that ultimate reality? The answer is simple; scripture. God out of His infinite Mercy has sent down scripture to guide us to that ultimate reality. Scripture (and more specifically communication by language, called sabda) is not established by a material mechanism like our other senses (like vision, hearing, feeling etc). This is because the sound carries meaning, and within that meaning the spiritual world is transmitted to us. This in the Vedas is known as sabda brahma (the sound form of God). That is why the best way to reconnect with God in this age is to always sing His holy Names, which are non-different from Him. Jaya Nitaai!
btw some of these arguements are really interesting. There is one which says that in the future it is possible to simulate another world perfectly, and we are actually in the future but in a simulation, and this life is only one simulation.