The perspicuity of Scripture is the clarity with which Scripture conveys to us the revelation of God. In part, the Reformation was about Scripture's perspicuity: is the message of the Bible (at least after translation into an understandable language) clear to its readers and hearers in its own right, or does it need the (formal/informal) M/magisterium of the church to clarify that message?
We can readily, with hindsight, conclude that what we have ended up with is quite a bit of "on the one hand ... on the other hand ...".
On the first hand, Protestantism both seized the right to translate the Bible from the power of Rome, and unleashed the Bible from its Latin chains, enabling its treasures to be read in local languages across Europe (and, later, spurred the work of Bible translators around the globe). At the very least, as a consequence, the ordinary reader could determine for themselves whether or not Scripture was clear, whether in its overall message or in its details. To say nothing of the ordinary reader determining whether or not Scripture and church teaching were well aligned.
On the second hand, Protestantism soon found that some magisterial assistance was required to ensure that (so to speak) the right clear message from Scripture was received through reading and hearing Scripture in one's own language. Cue various statements/articles of faith, Luther's Works and Calvin's Institutes. And, in more recent times, cue Protestant resistance to false readings of Scripture as propagated through, e.g., Jehovah Witnesses, Mormons. For those who know their German Reformation history, both Luther and Muntzer read the same Bible, to very different political conclusions!
On the third hand, Rome agreed to Bible translations and (after some initial resistance in the early 20th century) has encouraged full engagement by Catholic biblical scholars in the enterprise of academic biblical scholarship. In the world of biblical scholarship today, there is an alignment of interests and concerns which was scarcely imaginable in, say, 1525. Note, as one instance, the incredible, common reception of the New Revised Standard Version across Protestant and Catholic worlds.
On the fourth hand ... in the comments you might like to add an observation or three!
In other words, Catholics and Protestants have learned a few things from each other through the centuries.
But there remains work to do on the role of the Bible in the life of the church. For instance, sometimes in Anglican settings, I come across promotion of a certain kind of scepticism about the Bible in terms of understanding that its words collectively amount to God's Word written - this scepticism prefers to put more weight on "hearing what the Spirit is saying to the church" than on "the words as written and as we read them." Of course I have also come across promotion of a different form of scepticism in which the role of the Spirit in illuminating the meaning of Scripture is downplayed. To get the balance correct on such matters is is challenging - much ink has been spilled over the years.
Not least in the challenge, is the question of the perspicuity of Scripture: how clear is Scripture?
I recognise that the Bible is a complex set of books, of genres, with multiple layers of messaging, which often falls short of perspicuity.
A recent case in point, for me, was reading Psalm 17:14-15 (initially, NRSV).
I will cite from verse 13, because in this version verse 14 is a continuation of a sentence begun in verse 13:
13: Rise up, O Lord, confront them [= psalmist's enemies], overthrow them!
By your sword deliver my life from the wicked,
14: from mortals - by your hand, O Lord - from mortals whose portion in life is in this world.
May their bellies be filled with what you have stored up for them;
may their children have more than enough;
may they leave something over to their little ones.
15: As for me, I shall behold your face in righteousness;
when I awake I shall be satisfied,
beholding your likeness.
These verses struck me in this way: the psalmist sees around him satisfied, contented, materialistic, this worldly people (uncannily like many secularised Western persons in the 21st century) but is himself eager for something more, much more than that. The psalmist, verse 15, wants to see God.
Nevertheless this reading of verse 14 is at odds with verse 13: there the psalmist implores God to overthrow his enemies, whereas in verse 14 the psalmist seems quite comfortable with these same enemies having a good life.
Then I looked the verses up in some other translations and discovered some quite different translations of verse 14:
The Revised English Version (REB) has:
14: With your hand, Lord, make an end of them [= enemies of the psalmist];
thrust them out of this world from among the living.
May those whom you cherish have food in plenty,
may their children be satisfied
and their little ones inherit their wealth.
The first sentence here is in keeping with verse 13's diatribe. The second sentence changes the subject: no longer the enemies of the psalmist (and of God) but "those whom you cherish."
The Good News Bible (GNB) has a different translation again:
14: save me from those who in this life have all they want.
Punish them with the sufferings you have stored up for them;
may there be enough for their children and some left over for their children's children.
The first sentence continues verse 13 - the psalmist wants to be saved from his enemies, here described as those who have all they want in this life. But the second sentence is vindictive: may those enemies be punished and may the punishments stored up for them by God be sufficient to have punishments left over for their children and their grandchildren.
Between these three translations there is not much perspicuity in Psalm 17:14!
Looking up the commentaries, we find that the underlying Hebrew is difficult - so difficult that the MT has a marginal note or two, offering alternative readings. Hence the variations between English translations. Naturally this drives a reader to the commentaries (a form of magisterium) which are all united in saying ... that the Hebrew is difficult and one must wring one's interpretative hands to make sense of the passage.
The best of the ones I consulted is Goldingay, who offers a meticulously justified translation which is pretty close to the NRSV:
14: from mortals by you hand, Yhwh,
From mortals - in their lifetime will you fill their belly
with their share in life, with what you have stored up.
Their children are to be replete,
they are to leave what they have left to their offspring.
(John Goldingay, Psalms vol 1: Psalms 1-41, Grand Rapids, MI: Baker Academic, 2006, pp. 236-37).
Incidentally, in relation to the NRSV, I have come across a comment that "stored up" means the punishments that God has stored up in order to mete them out to the enemies. But Goldingay's translation does not support that sense.
Thus Psalm 17:14 is a puzzle and underscores that Scripture is not always perspicuous. Simultaneously 17:14 illustrates that Scripture has within it diverse ideas, because each of the possible translations of this verse can be matched to other statements in Scripture re the fate of the ungodly.
By contrast, 17:15 is much clearer. Moreover, it sets out one of the great, recurring themes of the Bible: that God will be seen by those who aspire to do so and to whom God reveals himself ... Blessed are the pure in heart, for they shall see God. Thus 17:15 illustrates that Scripture does have consistent theological themes, that we can reasonably expect to find in Scripture an understanding of God and the godly life, disclosed for our benefit and bearing witness to the character and identity of God.
Herein is something of a conundrum for those (such as myself) who lean evangelically within Protestantism towards an understanding of Scripture that Scripture is God's written Word - the whole of it.
Is it only God's Word when perspicuous? Does it remain God's Word when the text is somewhat mangled?
But here also is a possibility for evangelicals to sit more kindly within churches where diverse readings of Scripture are supported (such as many Anglican churches which belong to the Communion): acknowledging that Scripture is not perspicuous everywhere, that Scripture gives rise to multiple readings is a starting point for living with disagreement within the body of Christ.