Deadlocks are create on Wikipedia when an issue splits the community such that no consensus can be achieved. Where this happens it can cause conflict. Different areas have different methods of dealing with issues where no consensus is reached. In deletion debates, an admin can close a deletion debate as having no consensus, with the content being kept as a default position. In merge and page move debates a lack of consensus means no change. In areas of article content, the dispute resolution process applies, good faith editors working together to reach consensus, either through mediation or the involvement of other editors.
In terms of policy and guidance, it is less clear what a lack of consensus implies. Some feel that, like deletion and move and merge debates, no consensus implies a retaining of the status quo. Others feel that it simply means more effort must be made to reach a consensus, and that if no consensus exists, it means the policy or guideline should be set aside until a consensus is achieved. With policies and guidance settling a deadlock is especially important, since they set our direction. Although WP:NPOV is largely held to be non-negotiable, to the extent that those wishing to remove it are instead invited to fork, other policies and guidance are not held in such a manner, with the possible exception of WP:CONSENSUS. This latter policy is both the problem and the solution in a deadlocked issue regarding a policy or guideline. Since our policies and guidance only reflect what we consensually agree is our best practise, we need to simply establish that consensus as best as we can, with all editors working in a good faith manner to so achieve it.