I'm working off of Kant's conception of analytic/synthetic and a prior/a posteriori judgements.

The definition of "thoughts" does not subsume their existence. That is, it is logically possible to talk about thoughts in a world where humans are not around to think them. Therefore, "thoughts exist" is not true by the definition of what a "thought" is, and hence not analytic, but rather synthetic.

However, the fact that I am here right now having thoughts means that their existence is necessarily true. I do not need to go outside and look at the sky to confirm this, nor go to the library and read a book to confirm this. The fact that I had a thought necessitates their existence.

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    No. Feeling pain also does not require looking, at the sky or elsewhere, and you are not having thoughts in dreamless sleep or when you are dead, so having them isn't necessary. Both observations are empirical, i.e. synthetic a posteriori in Kant's terms, like any introspection. That having thoughts implies their existence may well be an analytic a priori conditional, but the fact itself of having thoughts (the premise) isn't a priori, analytic or synthetic. – Conifold Jul 22 at 4:03

As in Kant existence is not a property of individuals, "thoughts exist" is not a well formed judgement. "I am thinking" or "I am having thoughts" results from an introspective experience and is thus a posteriori (and hence synthetic).

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  • Interesting way of explaining it. Would you personally hold that there is no such thing as a synthetic a priori statement? – Mark Jul 21 at 16:48
  • Wait...didn't he try to show that such synthetic a priori statements are possible? – Mark Jul 21 at 16:52
  • Personally, I go with Quine when it comes to the analytic-synthetic-distinction. – Clyde Frog Jul 21 at 17:00
  • Thanks for your suggestion! I am currently working through it all from the ground up...I have Quine on the horizon :) – Mark Jul 21 at 17:02

I think that it is true that a 'thoughts exist' is synthetic, but not that it is a priori. Introspection (such as being aware that you are thinking) is a kind of experience.

You are right that, once had, the thought cannot be false - but that isn't the definition of a priori.

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  • Thanks for your reply. Isn't an a priori statement one whose truth can be arrived out by logical deduction alone, and not reliant on our contact with the world? – Mark Jul 21 at 16:49
  • Yeah but you cannot actually derive this statement ('thoughts exist') by logical deduction (in the way that you can derive 2+2=4 or equivalent). Your knowledge that you exist and are thinking is a type of de se knowledge ('of oneself;'); de se knowledge is very interesting, but it is surely a species of a posteriori knowledge not a priori. – Rollo Burgess Jul 24 at 8:17

It's analytical or, more properly, not a judgment at all.

In refuting the ontological proof of God, Kant famously says that "existence is not a predicate." One adds nothing to a subject by also stating that it "exists." Like cutting the Gordian knot, that was his way out of a lot of unproductive metaphysical tangles.

However, as I recall, Kant is a bit murky about the status of the self, and I'm not sure what he says about the Cartesian cogito, which might have some bearing on this "purified" version of it.

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"However, the fact that I am here right now having thoughts means that their existence is necessarily true."

Employing your statement as an axiom concerning human thoughts/ideas, we can then introduce Spinoza's Proposition 43 from Ethics Part 2, On the Nature and Origin of the Mind, as a corollary to your axion;

"He, who has a true idea, simultaneously knows that he has a true idea, and cannot doubt the truth of the thing perceived."

Explanation- No matter what differing skeptical schools of philosophy may say about doubts concerning human knowledge, your 'axiom' concerning the necessary existence of thoughts, coupled with Spinoza's proposition and his Note which will follow below, should help anyone to see, that if you know that your mind entertains adequate ideas, then please do not let anyone else convince you otherwise!

Note.— "I explained in the note to II. xxi. what is meant by the idea of an idea ; but we may remark that the foregoing proposition is in itself sufficiently plain. No one, who has a true idea, is ignorant that a true idea involves the highest certainty. For to have a true idea is only another expression for knowing a thing perfectly, or as well as possible. No one, indeed, can doubt of this, unless he thinks that an idea is something lifeless, like a picture on a panel, and not a mode of thinking—namely, the very act of understanding. And who, I ask, can know that he understands anything, unless he do first understand it? In other words, who can know that he is sure of a thing, unless he be first sure of that thing? Further, what can there be more clear, and more certain, than a true idea as a standard of truth? Even as light displays both itself and darkness, so is truth a standard both of itself and of falsity."

It is high time for each of us to move on from the self-negating philosophies which began with Descartes and his impossible claim to actually doubt those things that he truly knew.

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