Descartes, paragraph 2: Certainty is overrated

The second paragraph of Descartes’ Meditations says this:

But, to this end, it will not be necessary for me to show that the whole of these are false–a point, perhaps, which I shall never reach; but as even now my reason convinces me that I ought not the less carefully to withhold belief from what is not entirely certain and indubitable, than from what is manifestly false, it will be sufficient to justify the rejection of the whole if I shall find in each some ground for doubt. Nor for this purpose will it be necessary even to deal with each belief individually, which would be truly an endless labor; but, as the removal from below of the foundation necessarily involves the downfall of the whole edifice, I will at once approach the criticism of the principles on which all my former beliefs rested.

I love Descartes, but I don’t agree with him here. He says above, “my reason convinces me that I ought not the less carefully to withhold belief from what is not entirely certain and indubitable, than from what is manifestly false”. In other words, if I can’t be absolutely certain, then I shouldn’t believe it.

It seems to me that that standard is irrationally high.Descartes says reason convinces him of it, but reason convinces me of the opposite.

Descartes’ standard of belief is “if there is any possible way in which I could be wrong, then I shouldn’t believe it”. I don’t see how we, as finite humans, can possibly have the kind of certainty Descartes seeks.

In the second meditation, Descartes argues that we can be absolutely certain we exist because we experience ourselves thinking, and thinking implies existence.

1. If something does not exist, it cannot think.

2. I think.

3. Therefore, I exist.

That seems like a good argument, but it makes some assumptions.It assumes that we know what “something” and “existence” and “thinking” and “I” mean, for instance: that these are well-defined terms that can be used unambiguously in the argument above. The argument assumes that we have a world in which there are certain things which exist separate from other things, that existence itself is a clear category rather than being a spectrum from things that mostly exist to things that barely exist, that thinking is clearly what we are doing when we wonder if we exist, and so on. Let me be clear. I think these are good assumptions. I believe them. But I don’t think that they are absolutely certain, that it is impossible for them to be false. So they don’t have the kind of certainty Descartes requires.

Furthermore, for the argument to work, we have to be sure that it is logically valid. The argument pattern above is well-known. It’s even got a name: modus tollens. I agree with philosophers in identifying it as a trustworthy logical form. I cannot even imagine how it might be false. But it doesn’t follow that we can be absolutely certain of it.

It seems very clear that we cannot be absolutely certain of anything. That’s not a problem, though. Certainty is overrated.

Some philosophers after Descartes argued that the only reason we can think at all, the only reason we can even form logical categories to think with, is that we have available to us a whole bunch of assumptions about how thinking works and what concepts mean and how they are interrelated.There is just no way for us to clear all of them away and start reasoning  with no prior knowledge at all. We can’t even think coherently without them.

This doesn’t commit me to skepticism. I am not saying we don’t know anything. Knowledge has to do with justified belief. We can know lots of things, but only because we do not need absolute certainty about them in order to know them.

Because we can be certain of nothing, and because we need to assume something to think at all, it is rational to accept some things as true even though we can see a way in which they could theoretically be false. There are truths which are not certain and indubitable, but to which I should assent. Reason convinces me of this.

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Descartes, paragraph 1: Thinking like a philosopher

The first paragraph of Descartes’ Meditations says this:

SEVERAL years have now elapsed since I first became aware that I had accepted, even from my youth, many false opinions for true, and that consequently what I afterward based on such principles was highly doubtful; and from that time I was convinced of the necessity of undertaking once in my life to rid myself of all the opinions I had adopted, and of commencing anew the work of building from the foundation, if I desired to establish a firm and abiding superstructure in the sciences. But as this enterprise appeared to me to be one of great magnitude, I waited until I had attained an age so mature as to leave me no hope that at any stage of life more advanced I should be better able to execute my design. On this account, I have delayed so long that I should henceforth consider I was doing wrong were I still to consume in deliberation any of the time that now remains for action. To-day, then, since I have opportunely freed my mind from all cares [and am happily disturbed by no passions], and since I am in the secure possession of leisure in a peaceable retirement, I will at length apply myself earnestly and freely to the general overthrow of all my former opinions.


Since Descartes starts out by discussing the motivation for his meditations, I thought I would start out the PHL 102 semester by thinking a little bit about the habits of mind that make a good philosopher.

Question assumptions

First, there is the willingness to question one’s assumptions. Most people, most of the time, don’t question their most basic beliefs. Doing philosophy means being willing to look carefully at the presuppositions behind all our everyday opinions.

“I … became aware that I had accepted, even from my youth, many false opinions for true … I was convinced of the necessity of undertaking once in my life to rid myself of all the opinions I had adopted”

Some people talk as though whenever something is their opinion they don’t have to have a reason for it. That depends on what kind of opinion we are talking about. If my opinion is something like “I like chocolate ice cream better than vanilla”, then I don’t need much of a reason. If my opinion is “We will find life on other planets” or “Capital punishment is morally wrong” or “There is a God” then it makes a lot of sense to ask me to give some reasons.

Everyone has assumptions. We can’t think without them. Sometimes people who are trained to be objective about things – scientists and journalists and so on – think of themselves as making no assumptions, as being absolutely neutral. Philosophers know this is never true. No one is completely neutral.

At the same time, the assumptions we have matter. Everyone starts by assuming something, but that doesn’t mean that all belief systems are equally good. Some assumptions don’t make sense and/or don’t lead anywhere useful.

A good philosopher is intellectually humble. He is ready to change his mind whenever there is reason to. Some philosophers (and some philosophy students) become really arrogant in their philosophical understanding. That drives me crazy. I think philosophers should be the least arrogant people around, the most willing to listen.

Expect hard work

Second, philosophers know that getting to the truth about our most basic assumptions will be hard work. It’ll be tough both mentally and emotionally. It will take a deliberate decision to sift through everything.

It may take maturity. Sometimes young men or women, as brilliant as they may be, simply haven’t had enough life experience to develop the wisdom that guides their sifting.

Working through one’s assumptions may require being systematic and methodical. It may require writing things down. One of the hardest things to do in philosophy is to say what you mean clearly, so that other people can understand it.

There’s an interesting blog post about the value of philosophy here. Check it out.

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Descartes series

One of the things I want to do this semester is to work my way through the first meditation of Descartes’ Meditations on First Philosophy paragraph by paragraph. The source I will use is here: Go read it!

Here are my intentions:

  • I want this to be helpful and/or interesting for community college philosophy students, but I’ll try to keep other readers in mind too.
  • I want to keep it bite-sized. I’m only going to look at a paragraph at a time. The problem will be that by chopping the Meditations up into pieces, I may end up missing the overall perspective at times. Hopefully not!
  • I’m a little self-conscious about the fact that there are Descartes experts out there; I would be embarrassed to have one of them yell at me because I was wrong! Even though I am not an expert, I’m going to write as honestly as I can about what I think.
  • I want to understand Descartes clearly, but I am ready to disagree with him wherever it seems like I should.
  • I want to let Descartes’ ideas spur my own ideas. That means I’ll ramble from time to time.

More coming soon …

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