What's the difference between "sensus plenior" and "inspired sensus plenior"?
Are the terms interchangeable? If "the deeper meaning intended by God but not intended by the human author" (sensus plenior) exists wouldn't it be inspired?
Using Google, I find that "inspired sensus plenior" is most closely associated with Robert L. Thomas out of The Master's Seminary. More accurately, he coined the term "inspired sensus plenior applications (ISPA)" to describe a subset of the hermeneutical principles used by New Testament authors:
When interpreting the OT and NT, each in light of the single, grammatical-historical meaning of a passage, two kinds of NT uses of the OT surface, one in which the NT writer observes the grammatical-historical sense of the OT passage and the other in which the NT writer goes beyond the grammatical-historical sense in his use of an OT passage. Inspired sensus plenior application (ISPA) designates the latter usage. Numerous passages illustrate each type of NT use of the OT. The ISPA type of usage does not grant contemporary interpreters the right to copy the methodology of NT writers, nor does it violate the principle of single meaning. The ISPA meaning of the OT passage did not exist for man until the time of the NT citation, being occasioned by Israel’s rejection of her Messiah at His first advent. The ISPA approach approximates that advocated by Walton more closely than other explanations of the NT use of the OT. “Fulfillment” terminology in the NT is appropriate only for events that literally fulfil events predicted in the OT.—Robert L. Thomas, “The New Testament Use of the Old Testament,” The Master’s Seminary Journal (TMSJ) Volume 13, No. 1 (Spring 2002): 80.[PDF]
The term does not seem to have acquired much traction (though it's not been around very long in terms of Biblical scholarship), however. Perhaps part of the reason is that other thinkers do not feel the same need to separate the methods the apostles used from the methodology that is legitimate for modern exegetes. Richard Barcellos of the Midwest Center for Theological Studies notes:
[Thomas] assumes a very limiting view of hermeneutics. He says that grammatical-historical hermeneutics consists of “[i]nterpret[ing] each statement in light of the principles of grammar and the facts of history. Take each statement in its plain sense if it matches common sense, and do not look for another sense.” One wonders who gets to determine what constitutes “common sense” and if Jesus and his apostles would agree. Thomas’ view of grammatical-historical hermeneutics comes, in part, as a result of his commitment to what he calls the principle of single meaning. He sees the New Testament adhering to this principle sometimes, but abandoning it at others.
To put it another way, if we abandon the suspect notion that the only legitimate meaning of a passage is its "single, grammatical-historical meaning", there's no particular reason to cordon off sensus plenior into categories of "inspired" and not. Certainly it seems strange to hold the New Testament writers to the principles of the grammatical-historical method considering it has only recently come into fashion. Even that pillar of the Enlightenment, Isaac Newton, assumed there were hidden meanings to be found in the Bible.
Now we still have the problem in that if we don't hold the New Testament writers (or anyone else) to the grammatical-historical meaning, how can we avoid interpretations of the "fuller meaning" (i.e., sensus plenior) from being anything and everything the exegete wishes it to be? How can we allow the early Christian writers to arrive at their interpretations without simultaneously giving license for interpretations that indicate the world will end in 2060 AD?
One possible answer, appropriate in a Christian context, is the Christological Hermeneutic which finds Jesus at the center of all of God's plans. According to this reading of the Biblical texts, all divine revelation prior to Jesus was pointed toward the coming Messiah who would reconcile the broken world to God. Therefore, we should expect certain texts to include meanings beyond the immediate meaning the human authors had in mind. This is the principle Paul used when he applied Genesis 3:15 to Jesus:
I will put enmity between you and the woman, and between your offspring and her offspring; he shall bruise your head, and you shall bruise his heel.
—Genesis 3:15 (ESV)
The historical-grammatical meaning of the text seems to be a sort of just-so story. Working inductively from the text, the Christological interpretation seems strained to the point of breaking, but working deductively from the claims of Jesus of Nazareth, the interpretation is more than plausible. Considering it is a forward-looking statement from God concerning the fallout from sin, it's not surprising that Paul (and other Christians) would see the Christ sent to redeem the world in this text in addition to other meanings.
Dividing sensus plenior into "inspired" and "plain" flavors seems to be a solution to the problem of how early Christians were able to arrive at "non-literal" meanings of passages from the Tanakh without giving license to modern interpretations that eschew the historical-grammatical method.
"Sensus plenior" is used to speak of the higher meaning contained in scripture without regard to the arguments concerning who may or may not discern it.
Those committed to the literal-historical methodology use the term "Inspired Sensus Plenior" to affirm that the apostles recognized a fuller meaning in the Old Testament without endorsing a modern use of methods to interpret it. "Inspired" is used to say that because the apostles were apostles, only they were authorized to interpret the scriptures in a non-literal-historical method. Whenever confronted with a hermeneutical problem caused by the literal-historical method, they can claim "inspiration". 1
This argument is similar to Mormon claim for the Book of Mormon. There are no golden plates to examine so we must simply believe the word of Joseph and his witnesseswhen the translation has no basis. In the case of "Inspired Sensus Plenior", the literal-historical method is incapable of reproducing the methods of the NT authors, and so we must simply believe that their special revelation is true.
This is contrary to the evidence of the scriptures themselves. Jesus showed the disciples on the road to Emmaus all the scriptures that spoke of him. As the apostles preached, those who wished could verify what they said against the OT as the Bereans did.
1 THE NEW TESTAMENT USE OF THE OLD TESTAMENT -- Robert L. Thomas
Whether sensus plenior (either inspired or not) exists is largely a question that depends on the particular doctrine an interpretation is evaluated in. Certainly the early Christian writers believed that the Hebrew Scriptures they inherited contained important links with the man they had come to revere as the Messiah. There's no particular reason why they wouldn't continue to use all the tools of interpretation available in the culture they were active in.
Among the Dead Sea Scrolls, we find examples of an interpretative technique call Pesher, which re-interpreted the Tanakh in light of current events. There's no particular reason to suppose that early Christian authors, most of whom were Jews, would not try their hand at the same technique. In fact, we know that Jesus himself interpreted the prophesy in Daniel 7 as a being fulfilled in himself. So it's no particular surprise that his followers would not discover hints of Jesus' life in the Tanakh as well.
God only knows whether or not any particular interpretation is inspired. Certainly the authors of the New Testament believed they were discovering deeper meaning in Scripture. However, there's no particular need for us to follow their precise techniques since those methods are not commonly used in our culture.