The phrase "are sensible only" is correct and usable in written English.
It can be used to indicate that something is reasonable or logical under specific conditions or contexts.
Example: "The solutions we propose are sensible only when considering the long-term effects on the environment."
Alternatives: "are reasonable solely" or "are logical only".
Some of the rules are sensible (only free-range eggs may be labelled as such).
Getting to your question of morality, for example, science provides the basis for moral decisions, which are sensible only if they are based on reason, which is itself based on empirical evidence.
On the other hand, the common targets of the pairs of miRNAs are sensible only when (i) down-regulation of their common targets causes cancers, and (ii) their common targets have normal or high expression in normal tissues.
This approach is sensible only if the number of neighbours is sufficiently bounded (so that the cost incurred by the direction summation remains small).
Finally, such precision medicine strategy is sensible only if it benefits the patients.
Naturally, the distinction of species based on differences in their responses to ecological factors is sensible only if there are actual response differences.
Alternative measures can be derived from eigenvalues of a correlation matrix; however, this is sensible only for distributions in which linear relationships between variables are meaningful.
Proposals to use cash in dormant betting accounts to fund grassroots sporting facilities – a Lib Dem idea – are sensible but will only raise around £10m a year.
Barack Obama has tried to use this crisis to gain more political and popular support for his clean energy bill – which is sensible, but only underlines how little progress America has made in this direction.
And if GVP doesn't stop trying to develop messaging based on some questions about "sensible" gun solutions that are considered sensible only by the GVP, all the Pew polling won't change the ultimate result one bit.
After dark, as in many other major cities, it's sensible to walk only in well-lighted areas and travel in groups, among other standard anticrime strategies.
