Descartes part 2 – Do external objects exist?

To quickly summarize, first part of this blog entry covered Descartes’ argument as it pertains to whether we truly exist. “I think, therefore I am” he concludes. Descartes considered that his ‘Archimedean point’ as it is the foundation that everything else can be built upon. To get to that point, he had to doubt everything. The only thing he could not doubt was his actual ability to doubt. That single point is the crux of his entire argument proving why he exists. More importantly, we see his entire theoretical thinking process of how he devises his argument step-by-step.

I recommend reading the first part before this to limit any confusions: Descartes Part 1


Next piece of his argument is the third through sixth meditations. This is the point where we enter controversy. Many philosophers after Descartes had problems with the logical notions Descartes sets henceforth beyond the second meditation. Most famously, German philosopher Immanuel Kant took apart Descartes’ third, fourth, and fifth meditations (Kant is for a future blog entry as he is also top 15 greatest philosophers of all time). Honestly, I do not know where Descartes was going with this part of the argument.

Funny rap video I found of Descartes battling Kant based on South Park (note: some cursing/language involved):

I should mention that this blog entry will focus on Descartes’ third, fourth, and fifth meditations, which focus deeply on religion. I will keep it neutral as much as possible. There will be no discussion on my own religious perspectives as that is not something I will get into on this blog (if I went into that, I would probably anger every religious and atheist person alike haha).

 Descartes’ Third, Fourth, Fifth Meditations

The basic idea of these three meditations is simple. Here’s a quote from paper I wrote for one of my philosophy classes that concisely summarizes these three meditations:

After his famous ‘Cogito ergo sum’ argument, Descartes has reached a point where he has proved he exists, but he needs to go on further to make an argument of what exists outside his mind, which is where our bodies dwell along with all other external objects. In order to prove the existence of an external world, he makes a leap of faith to make his critical argument by proving the existence of a perfect being – God. Since God is infinitely good, he/she/it would not deceive him. That proves to him that the ideas that we have of the external world, through our minds, must hold true just as they truly are.

There is more to these three meditations, but this quote essentially goes through the main ideas. Descartes’ goal here is to make religion compatible with knowledge (Banach, n.d). If everything you know is based not on your senses but entirely your mind then how do you fit religion into the equation? Does that mean god exists only in your mind and not reality? Descartes was entering very dangerous territory as questioning religion at all in that era meant death (along with all his writing work banned & burned), but that is when he takes a turn.

Descartes’ Ontological Argument

To show his proof of the existence of god, Descartes says that we have this idea in our minds of a perfect all-powerful being called god. The ‘idea’ of god cannot exist if god does not truly exist. This is where we come across a form of the Ontological argument, which in simple terms states that since god is an infinite/perfect being and since human mind is finite/imperfect, one would not be able to imagine god if god did not exist in reality. Therefore, perfect god must exist in reality if he/she/it exist in our imperfect mind. That is the ontological argument in simplest terms (original form was put forth by Anselm of Canterbury in the 1000’s). This is, in essence, the third meditation.

I think Descartes draws this argument from the first two meditations. Recall that Descartes made the argument that since I have the idea/ability to think, I exist. Since I have the idea of god, god must exist as well.

Descartes’ argument, in my view, is problematic because according to his argument, everything must exist if we simply have the idea of its existence being perfect. It raises questions that other philosophers since Descartes have asked. I would ask Descartes: does this mean if I have the idea of an infinite spaghetti monster, then the infinite spaghetti monster must exist? Now, I cannot say that there is definitely no infinite spaghetti monster as the universe is too large to know for certain (and there might also be infinite numbers of universes if multiverse theory is correct), BUT I also cannot say that there is definitely an infinite spaghetti monster simply based on my idea of it.

Descartes may respond with something like “God is something that which nothing greater can be conceived so how can your infinite spaghetti monster be greater?” I would have no response to that except maybe “But what if my infinite spaghetti monster is greater than everything since it oversees the entire multiverse system far beyond our universe and is greater than anything your mind cannot even conceive of since the monster exists outside of our universe?” Anselm said god is something that which nothing greater can be conceived, but what if there is something so powerful that you cannot conceive (since it is so powerful)?

See, what sets philosophy apart from most other fields of study is that every philosopher is trying to outwit another. The counter-argument I put above is not an original idea of mine; it is based on other philosophers. Any Immanuel Kant fan will notice that he made similar arguments and even he was inspired by others before him. Some philosophers have plugged in different things in place of god to try to logically outwit each other (evil demon, unicorns, bananas, etc) — yes, many of the greatest philosophers would be called ‘trolls’ today haha. Kant argues that this entire ontological argument “rests on confusion” and that thoughts alone cannot prove the existence of god (Pecorino, 2000). “The idea of the GCB [Greatest Conceivable Being] exists and the idea of the GCB as an actual being does exist but the reality or actuality of the GCB is not established based on the thoughts alone” (Pecorino, 2000).

I will leave it at that as my goal here is not to disprove ontological argument or discuss Kant or other philosophers. That is for you to contemplate and decide. As far as I am concerned, Descartes at this point believes he has proved the existence of god based on his form of the Ontological argument.

The fourth meditation builds on the third. Fourth meditation states that since god is perfectly good, god would never deceive. According to Descartes, only an imperfect being would deceive. He goes on to argue that since god is not a deceiver, god gave free will to do as we choose. Since our free will comes directly from an infinite god, our free will would be infinite too. Since our knowledge of the world is not infinite due to us being flawed, that is one thing that does not come from god (Descartes, 1637). That is the entire fourth meditation in a nutshell.

The fifth meditation is very similar to the third meditation above. Descartes says that we have an idea of a triangle in our minds without it being existent in front of us. We are simply born with the idea of a triangle since it exists in nature. Simply from our minds, we can figure out the characteristics of the triangle (3 sides, 3 angles that add up to 180 degrees, etc). So he says god is the same too. Another philosopher would probably argue “A baby does not know a triangle from a square until they are taught or shown by somebody else.” In the same way, no baby is born a certain religion until he/she is taught by somebody else. Regardless of counter-argument, Descartes believes he has proven god at this point concretely.

External Objects/Sixth Meditation

The sixth meditation is where it gets confusing (this meditation is long, complicated & difficult to explain). This is where Descartes tries to prove the existence of external objects. To start, he says that we have the ability to understand something complex but we cannot imagine it. His example is that we can understand a 10,000-sided geometrical figure, but we cannot draw it in our minds using imagination (Descartes, 1637). Therefore, imagination is not necessary to our being – he discards imagination from his mind much like he discarded senses in the first meditation.

external objects

Photo by Tom Magliery / CC BY

As for external objects, this goes back to the last two meditations. Recall that Descartes argues that since I have the idea of an infinite perfectly-good god, god must exist. His argument for external objects is similar (Banach, n.d). If god makes me believe these objects exist when in fact they do not, then god is a deceiver. Since the fourth meditation proves that god is perfectly good, god would never deceive. That means the only thing that can prove external objects exist is external objects themselves. Therefore, external objects exist. Yes, there are flaws in this argument as well, but don’t question it yet.

What do we know so far? We know that thinking being exists, we know that god exists, and we know external objects exist.

In the fifth and sixth meditation, he also says that mind/body are separate entities. For that, he looks towards another philosopher Gottfriend Leibniz, who had a mathematical law that said “If two things are the same thing, they must share all the same properties” (Banach, n.d). If mind and body were the same then they would need to have the same properties and abilities. The mind I can prove exists by simply thinking, but the body I cannot prove. Therefore, they have different properties and are not the same. This is called the dualism argument. Descartes differentiates in the following manner:

“So, mind and body are separate and distinct, allowing for certain faculties – notably will, understanding and all forms of thinking – to be associated with the mind, and other faculties – such as the senses and imagination – to be associated with the body. According to this model, what the mind sees clearly and distinctly as true must necessarily be true. However, once interaction with the body and the physical world begin – through imagination and sense experience – things become less clear and our understanding becomes more prone to error” (Southwell, 2012)

Descartes, in another writing, goes into a crazy argument about how our souls are stored in our pineal gland, which we now know is responsible for circulating hormones and our sleep cycles. It becomes difficult to take Descartes serious at times.

Even though there is more, I will leave this as it is.


If anybody took geometry in High School, they will see that Descartes set these arguments like geometry proofs. A -> B -> C -> D. If B is flawed then C would be built on that flaw and D would be built on C’s flaw. If you show B is flawed then the rest of the arguments after B will fall like a stack of cards. That is what philosophers like Kant, Bertrand Russell, David Hume, etc focused on to counter Descartes (google Antoine Arnauld‘s famous ‘cartesian circle’). I cannot go into all those counter-arguments here.

It is hard to say what Descartes’ religious beliefs truly were. Some say he was a devout Christian. Some say that Descartes was an atheist trying to convince religions (for Descartes, most of France was Catholic in 1600’s) to accept the sciences by showing that religion does not have to shun science as there is a possibility for both to work together. Remember, there was a lot of friction in 1600’s between religion and science in Europe at this time – most people practiced science in hiding essentially as it could get you thrown in jail or killed. Descartes stayed far away from getting involved in this friction in his writings so we have no way of knowing. All we know is he said he is a devout Christian, but others in his time like Blaise Pascal openly called him an atheist (Wikipedia).

His religious views are further complicated in future papers. In 1633, Descartes wrote a paper he called ‘the method of rightly conducting the reason, and seeking truth in the sciences.’ In it, he questioned how reasoning should be done to seek knowledge of the world.

“But just before it was ready to go to print in 1633, Descartes got wind of Galileo’s condemnation by the Inquisition for his ideas about the Earth revolving around the sun. Realizing that his own book could raise some of the same theological problems, Descartes canceled the publication and hid the manuscript. The first part wasn’t published until 1662, 12 years after the author’s death. And Descartes was right to worry: In 1663, the pope placed The World and the rest of Descartes’ works on the Index of Prohibited Books” (Grossman, 2010).

Overall, Descartes was an interesting character in the history of philosophy. He changed the course of history, and how we devise arguments. Much of his work is debated, but I believe the mark of a true genius is one that is able to start a discussion that may never end in a method & style that HE devised.



Sources for part 2:

Banach, D. (n.d.). Important Arguments from Descartes’ Meditations. Retrieved December 31, 2014, from

Descartes, R. (1637). Discourse on the method of rightly conducting the reason, and seeking truth in the sciences.

Grossman, L. (2010, June 8). June 8, 1637: Descartes Codifies Scientific Method | WIRED. Retrieved January 4, 2015, from

Pecorino, P. (2000, January 1). The Ontological Argument. Retrieved January 5, 2015, from
Southwell, G. (2012, March 19). Meditation VI: Overall Summary. Retrieved January 6, 2015, from
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Harsh Shukla

I am an Information Technology graduate from Rutgers University New Jersey, USA. I like to blog about my interests in science, technology, philosophy, and about the wonders of life.
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