heh, heh.....Death? Contradictory answer! heh, heh.....
I am afraid that you have created confusion in my small mind, Punjabi. I hope you don't mind that I used a popular online resource but I think we can agree that its definition is accurate.
con·tra·dic·to·ry /ˌkɒntrəˈdɪktəri/ Pronunciation Key - Show Spelled Pronunciation[kon-truh-dik-tuh-ree] Pronunciation Key - Show IPA Pronunciation adjective, noun, plural -ries.
1. asserting the contrary or opposite; contradicting; inconsistent; logically opposite: contradictory statements.
2. tending or inclined to contradict.
3. Logic. a proposition so related to a second that it is impossible for both to be true or both to be false.
Number 1 can't be what you intended since Death and certainty are not natural opposites. Arguing points possibly but not specifically opposing words or ideas.
Number 2 is simply a grammar rule applied to the first definition.
Number 3 is stating that if Death is true, Certainty cannot also be true. This would lead to the question, "Do you have definitive proof that they are both not true (or false)?" If so, please elaborate. If not, then you could not have meant Number 3.
If none of the above definitions fit what you were trying to say, then perhaps you have misused the word?