How is conflict handled in the case of smart contracts .For eg -in the case of an insurance smart contracts,there might be conflit between both parties.How does blockchain ensure the validity of trigger conditions
Conflicts in contracts should be handled by the contract's logic. The BlockChain technology will ensure that there are not inconsistent transactions, for instance, it will ensure that a person no double spend or that people cannot deny transactions.
In the case you are presenting, the conflict is part of the possibilities and a good design need to account for this. For instance, a third party may be invoked to make a decision if a conflict is reported (like in escrow contracts).
For example, assume the case of someone selling goods, the seller will receive the money when the package is delivered. If the buyer doesn't report that receive the goods (in bad faith) the contract could have as input the delivery proof from the delivery company, such that the seller receives the money. On the other side, if the seller never sends the package, the contract could have a time limit for delivery proof to be provided, in such case the money is returned to the buyer.
As you see in this example the contract logic is what resolve conflicts, all this backed by the blockchain making sure that the involved transactions a not invalid in the network.
Hope this help