Like can you gain insight into the four noble truths by contemplating them? In this sutta the Buddha says that "your duty is the contemplation" and then goes into the four noble truths http://www.accesstoinsight.org/tipitaka/sn/sn56/sn56.048.than.html.
Contemplate here doesn't mean thinking about it intellectually. Sure we all have to think about it first but real insight happens when you realise it through direct experience.You have to experience the four noble truth not churn it through your head back and forth trying to get a sense of it.This is like contemplating how a mango tastes a hundred times Instead of just picking up the fruit and tasting it.
The relevant Pali of that sutta is:
which means roughly "The setting oneself upon should be done"; i.e., one should focus one's efforts on "this is suffering", etc.
A word meaning "contemplation" is not found in the Pali. The word yoga here actually relates to the context of the sutta, since it means, literally, "yoke", as in the yoke that the turtle puts its neck under in the allegory.
The commentary explains that there are four yokes that one should yoke oneself to:
manussapaṭilābho - the attainment of humanhood
tathāgatuppādo - the arising of a Tathagata (i.e., being born as a human during...)
tathāgatappaveditassa dhammavinayassa dīpanaṃ - the elucidation of the dhammavinaya of the Tathagata (i.e. listening to...)
catusaccapaṭivedho - the realization of the four noble truths
It is this last one that is described by the Buddha; he is most definitely referring to paṭivedha or realization, not contemplation.
As to your question, directly, if by contemplation you mean intellectually, then no, it is not possible to become enlightened through intellectual contemplation, since the mind is not focussed on ultimate reality (i.e. as it occurs) at that time. If by contemplation you mean empirical observation, then one should only observe the first noble truth - the second and third come as a result of that, and the fourth is that observation itself.
Another way to look at it is when looking at theoretical physics and experimental physics.
Take a scientist for example. He has a theory about e.g. gravity. Its only a theory on the drawing board. He contemplates it thoroughly and does his calculations.
Will he get insight into how reality functions?
No he will not. Why? Because he has not testet his theory on reality.
Then lets take it a step further. Lets say that this scientist now wants to test his theory in practice. He now conducts an experiment in reality where he tests this gravity theory. He then gets his results and see that part of his theory was correct and the other part was not in line with reality. He can now reevaluate his theory and make it more precise and then go test it again.
Has he now gotten insight into how reality functions?
Yes he has. That is the difference between theoretical, intellectual, "book" knowledge AND experiental knowledge.
It is helpful to think and contemplate but know the limits of the intellect. It is helpful to try to grapple with these concepts intellectually but that is it.
Only contemplating is like reading a restaurant menu and knowing all the food but never actually ordering it and tasting it.
Or like planning a trip but never actually making the trip.
Contemplation can only get you so far.
Insight into the 4 noble truths and how reality functions is achieved by looking. By observing mindfully. By doing insight meditation practice.