Change and impending death.

It should also be, "I think, therefore I pay taxes."

Good question, we can be certain we will never have all the answers.

Perception is reality to an individual. Physical example, if I am colorblind, green to me is different than it is to you. Also, Rene Descartes was a drunken fart who was very rarely stable. I drink, therefore I am!

You should read some Kant. Kant was the follow-up to Hume (Who denied that ANYTHING exists, even the self!), and established the Phenoumena/Noumena idea, which says that there IS, in fact, a physical reality, however our minds interpret in such in a way that we can never have DIRECT experience of the TRUE physical reality. He also introduced the faculty idea, wherein we have Faculties of Intuition, thinking, etc.

Descartes established in the collective thought of intellectuals, that intellectuals is what we all are. This is a perception, and as stuck in perception as intellects are, they have not yet gone beyond to see the dysfunction in the mind identified self. The mind identified self, in the mind. Simon says, I know for sure that, "In thought I can not know that I AM." Blessings.

Collective unconscious is a term of analytical psychology originally coined by Carl Jung. While Freud did not distinguish between an "individual psychology" and a "collective psychology", Jung distinguished the collective unconscious from the personal unconscious particular to each human being. The collective unconscious is also known as "a reservoir of the experiences of our species." It thus directs the self, via archetypes, dreams, and intuition, and drives the person to make mistakes on purpose. In this way, it moves the psyche toward individuation, or self-actualization. The concept of the archetype, which is an indispensable correlate of the idea of the collective unconscious, indicates the existence of definite forms in the psyche which seem to be present always and everywhere. Mythological research calls them "motifs"; in the psychology of primitives they correspond to Levy-Bruh's concept of "representations collectives," and in the field of comparative religion they have been defined by Hubert and Mauss as "categories of the imagination." Adolf Bastian long ago called them "elementary" or primordial thoughts." It is the repositary of all the religious, spiritual, and mythological symbols and experiences. Every person can be certain of being influenced by the collective unconscious. Only the degrees of influence may differ from person to person.

That you will die. Since you are the I AM (God), salvation shouldn't be a problem...if it is reconsider who you are.

It's obvious that the ONLY thing we can be certain about is that 'we can't be certain of ANYTHING'

Slippery slope, dude. Descartes only established that he believed he thought he existed! What does that have to do with a hot breakfast, dig? (Humbly, I'll only amplify/expound/elucidate upon request.)

Not sure which recent philosopher debunked Descartes, but he did it by saying that it is wrong to jump from "I think" straight to "I am". all you can really say is "I think therefore there is a thought"

We know that if we don't exist, we all at least have overly active and remarkably similar imaginations!

We can be certain of doubt, because if we doubt that we can doubt, then we are doubting.

I think, ( pardon the pun) that death on this plain is also a certainty,

"Nothing is certain except death and taxes" --Benjamin Franklin, 1789

just that we exist