are there any theories against solipsim??

Question

or cartesian skepticism??

Answer 1

Solipsim:

If you aren't real and don't exist, then how did you manage to imagine anything?

Also, you could argue that "figment of the imagination" is an arbitrary term, since there is no clear difference between reality and illusion anyway.

Cartesian Skepticism:

Cartesian skepticism is a direct, non-iterative form of substantive skepticism that states what criteria are required for knowledge. The first criterion is that, in order to know something, one must rule out every alternative fact that is consistent with one’s evidence. Next, in order to know fully that one knows a fact, one must also be able to rule out all alternatives consistent with the falsehood of the target belief. For example, one could not be sure he is viewing a star in the sky unless he can rule out the alternative that he is seeing a plane, being deceived by a demon, or hallucinating. Also, to truly know he is viewing a star, he would have to be able to rule out every alternative consistent with the idea that he is not seeing a star. After setting this preface for what is and isn’t knowledge, Cartesian skeptics then say that one can never rule out all alternatives, and, therefore, none of our beliefs can ever count as knowledge.

Click here for more:

http://www.mandatorycurfew.com/media/drldocuments/DerekLidbom_CartesianSkepticism_1999.htm