Cassandra asked:

I actually have two questions for you tonight. One is about a question that we were asked in class
today, and another is about something that I have a problem with. So here are the questions:

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Is "I think therefore I am" an 'a priori synthetic' knowledge statement, and if it is why is it? If it isn't why
isn't it?

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Also my other question well is more a statement of my own. I would like someone else's view or
explanation on it. In my philosophy book, the definition for 'synthetic a priori' goes like this. 'Through
reason, independently of experience and expressing information about the world.' (Paraphrased from
my notes so it doesn't exactly say that.) My problem with that definition is the examples it gives for
these things. One example is that all apples are green. Well to me we gain this knowledge from
experience, like if I had never seen an green apple before I would not believe it was green until I
myself saw one, and then I would be able to make this statement. So anyway could someone please
explain to me what exactly synthetic a priori knowledge is and send me in the right track? Thank you
so much for your help.

I think it would help to answer the second question first; a good understanding of what 'a priori
synthetic' propositions are leaves one is a strong position to evaluate whether particular propositions
are 'a priori synthetic' or not.

Lets take the a priori bit first; in philosophy the phrase is generally taken to mean something like '
without (prior) experience'. Among true propositions, some are true independently of experience and
will remain true however individual experiences differ. Mathematical truths, one might think, are a
good model for these kinds of truth. 7 + 5 will always equal 12 in our normal number scheme. Other
truths on the other hand owe their truth to experience and might have been false had experience
differed. This latter set — which are a posteriori truths in the jargon — I take to be questions which we
would verify by sense experience. The position of the chess pieces on the board to my left would be
determined in an posteriori manner.

Now onto the analytic part: analytic propositions are ones like 'all bachelors are unmarried'. The truth
of the sentence is guaranteed by the meaning of the subject. A proposition like 'All bachelors are
sensible' would be an example of a synthetic proposition. These kinds of proposition say something
substantial and do not simply restate the meaning of the subject (where bachelor here is the subject).
They tell us something about the nature of the thing in question, or predicate something of it that is
not simply a tautology or a reiteration of the subject's meaning.

Kant famously insisted that the a priori/ a posteriori distinction is not the same as the
analytic/synthetic distinction. In other words, not all a priori truths are analytically true (and vice versa)
and not all a posteriori truths are synthetically true (and vice versa). It is somewhat uncritical to think
that truths that are independent of experience (a priori) are true if and only if the predicate is
contained within the subject of the proposition.

It is just as uncritical to think that substantial synthetic claims like 'Every event has a cause' are
always known to be true 'a posteriori' or 'through experience'.

Now we are in a position to appreciate what 'a priori synthetic' claims are. 'A priori synthetic' refers to
a class of claims which we can make quite independently of our experiences, but which are not true
in virtue of definitions alone. That is to say, they are not trivial statements like 'all bachelors are
unmarried', but are ones (for Kant) that say substantial things. For Kant, this includes talk of our
intuitions of space and time, and the concepts of causation and substance. What he is saying is that I
do not form my idea of space from the experience of space; it is a priori just to the extent that the
existence of space is presupposed in my experience. And claims like 'All things occur in space' are
clearly not analytic, but synthetic and substantial. So they are a priori, but this does not affect their
status as synthetic.

This line is in part a response to the empiricist school who famously hold that all knowledge is
imparted through sensory experience; what Kant makes clear is that there are claims to knowledge
which we make not in virtue of this or that experience, but because the truth of these claims is
presupposed in experience on general.

More controversially, Kant also thought that mathematical propositions like 7 + 5 = 12 are
synthetically true; it may seem at first that mathematical propositions ought to serve as a prime
example of analyticity but Kant holds that the notion 12 is not contained as such in the notions of 7
and 5. That is a real philosopher's question of course, but I think there is something right in Kant's
approach to the terminology.

Now to your first question: is Descartes' 'Cogito' an a priori synthetic claim to knowledge? You can
judge for yourself. I'm not sure that I think Descartes was entitled to draw the inference that 'I exist'
from the fact that 'I think' ; what he should have claimed is that there is a thing that thinks, not that
there is an 'I' who thinks it. But as to its a priority, we can be pretty sure that when we think, we do so
independently of sensory experience. I do not need an experience to verify that I am thinking — the
fact that I am thinking about thinking confirms that I am thinking. And I don't believe that the notion of
'thinking' strictly contains the idea of 'existing', although one might engage with that by saying that
thinking requires embodiment or something of that sort. But broadly it seems right that 'I think
therefore I am' is an a priori synthetic proposition. Whether Descartes' 'I exist' is a true claim, or a
claim to knowledge is however another question.

Adam Gatward