Thank you, slimboyfat and Narkissos, for shedding more light on Furuli's position. I see that Furuli takes his cue here:
*** it-1 p. 858 Foreknowledge, Foreordination ***The apostle Peter’s statement that Christ, as the sacrificial Lamb of God, was “foreknown before the founding [form of Greek ka·ta·bo·le′] of the world [ko′smou]” is construed by advocates of predestinarianism to mean that God exercised such foreknowledge before mankind’s creation. (1Pe 1:19, 20) The Greek word ka·ta·bo·le′, translated “founding,” literally means “a throwing down” and can refer to the ‘conceiving of seed,’ as at Hebrews 11:11. While there was “the founding” of a world of mankind when God created the first human pair, as is shown at Hebrews 4:3, 4, that pair thereafter forfeited their position as children of God. (Ge 3:22-24; Ro 5:12) Yet, by God’s undeserved kindness, they were allowed to conceive seed and produce offspring, one of whom is specifically shown in the Bible to have gained God’s favor and placed himself in position for redemption and salvation, namely, Abel. (Ge 4:1, 2; Heb 11:4) It is noteworthy that at Luke 11:49-51 Jesus refers to “the blood of all the prophets spilled from the founding of the world” and parallels this with the words “from the blood of Abel down to the blood of Zechariah.” Thus, Abel is connected by Jesus with “the founding of the world.”
As Narkissos already pointed out, katabolé spermatos is itself an established idiom for sexual procreation (Galen, In Hippocratis vii 17b.653.7, Philo of Alexandria, Legatio ad Gaium 54.5, De Specialibus Legibus 3.36.5, Plutarch, Moralia 320b, Pseudo-Lucian, Amores 19.21, Pseudo-Galen, Ad Gaurum 17.2.1), and the planting of seeds (Philo of Alexandria, Quis Rerum Divinarum155.3, Quaestiones in Genesim 3.12.3), with the sexual metaphor being derivative of the latter, and it is inappropriate to decompose this idiom and assign a connotation of procreation to an altogether different idiom that has its own distinct context. I see that Furuli does try to import a procreative sense from katabolén spermatos (Hebrews 11:11) to the expression katabolé kosmou elsewhere in the NT:
Furuli: Most readers would get the impression that the reference here [in Ephesians 1:4] is Genesis 1:1 and the creation of the earth and the universe. However, KATABOLH does not refer to creation in the NT and an alternative view is that it refers to begetting children (Hebrews 11:11) and that Ephesians 1:4 refer to the children of our first parents. [source]
But katabolé kosmou is a distinct expression that has its own metaphorical basis; in other words, Furuli is mixing metaphors. As even the Society admits in the above quoted passage, apo katabolés kosmou in Hebrews 4:3-4 does not fit with this interpretation since it refers to the completion of God's creative work (ergón) PRIOR to the supposed "fall of man". The same is true with Barnabas 5:5 and there the reference is explicitly to the creation of man on the sixth day. I'm not sure what you mean in saying that the phrase in Barnabas is "linked with the arrival of humans rather than the physical creation," since it is concerned with the physical creation of man in Genesis 1:26 and not the procreation of Adam and Eve after the "fall". If the main issue in interpretation is whether God predestined Christ in a redemptive plan PRIOR to the "fall", then Barnabas is evidence that the expression apo katabolé kosmou was indeed used to refer to the world's founding PRIOR to the "fall".
The metaphor in katabolé kosmou is primarily architectural, laying foundations or founding as one does a building (cf. themelion kataballomenoi "laying foundations" in Hebrews 6:1; cf. similar expressions in Josephus, Antiquitates Judaicae 15.391, Aristonicus, De Signis Iliadis 5.31, Origen, Contra Celsum 3.28.8), and in the OT the creation of the earth was also conceptualized as involving the laying of foundations (Job 38:4, Psalm 102:25, Proverbs 3:19, Isaiah 48:13), although in the LXX the terms used were themelion and gés and not katabolé and kosmos. In its architectural sense, katabolé refers to not just the laying of foundations but any kind of building activity (cf. Polybius, Historiae 1.36.8 and Diodorus Siculus, Bibliotheca 12.32.2 where it refers to the activity of shipbuilding) -- and similarly it can refer to the building as a whole, e.g. "The architect of a new house (kainés oikias) must give his attention to the entire building (holés katabolés), while the man who undertakes the decoration and the frescoes has only to concern himself with what is needed for ornamentation" (2 Maccabees 2:29). The term was generalized further to refer to any kind of "beginning" of a thing, like a revolt (Josephus, Bellum Judaicum, 2.260). The idiom katabolé kosmou as a "founding of the world" clearly has reference to God's creative activity in Hebrews 4:4-5 and Barnabas 5:5, but it also has reference to creation in Chrysippus (third century BC) who used the expression apo ktiseós kai katabolés kosmou (Fragmenta Logica et Physica, 989.40) and the second-century AD apologist Theophilus similarly paired apo ktiseós kosmou with apo katabolés kosmou (Ad Autolycum 3.28.2). Also noteworthy is the use of katabolé alone for God's "creation" (in a sense similar to how 2 Maccabees uses it to refer to the entire "building") in Aristeas (second century BC): "Since there is one creation only (mias katabolés ousés), why is it that some things are considered unclean for eating, others for touching, with legislation being scrupulous in most matters but in these especially so?" (Epistula ad Philocratem 129). The pre-Christian use of the expression in the Assumption of Moses (first century AD) also clearly has God's creative activity in view: "For he created the world (Latin creavit orbem terrae) on behalf of his people, but he did not reveal the purpose of the creation (creaturae) from the founding of the world (ab initio orbis terrarum), so that the nations would be put to disgrace on their account, and through their deliverations among themselves, to their own humiliation disgrace themselves. Therefore he has devised and invented me, as God foresaw before the foundation of the world (Greek pro katabolés kosmou, Latin ab initio orbis terrarum) that I would be a mediator of his covenant" (1:12-14). Furuli however asserts but does not show that katabolé cannot refer to "creation" in the NT.
There were quite few idioms with katabolé. "Laying down seed" had the idiomatic sense of "procreating", "laying down foundations" had the sense of "founding", "building", "creating", "laying down money" had the sense of paying a regular tax or fee, "laying down a period" had the sense of scheduling a regular event, and so forth.
slimboyfat: Well if God predicted the need for a mediator before the creation of the physical world that would imply God knew that Adam would rebel before he created him. If on the other hand the phrase "founding of the world" refers to the arrival of Abel and the start of the human family, that places God's prediction for the need of a mediator after man's rebellion, and thus preserves the JW teaching that God chose not to know whether humans would rebel or ramain faithful when he created them. When Adam sinned, and together with Eve produced imperfect offspring, that is when God could predict the need for a mediator to put things right, not as early as the creation of the physical universe.
As the quote above shows, this is not what the passage itself says. It refers to God creating the world (creavit orbem terrae) and when God created the world, there was a purpose of his creation (intentionem creaturae), and that original purpose included the election of Israel and the humiliation of the nations -- thus God foresaw that Moses would be the mediator of the covenant "before the foundation of the world" (pro katabolés kosmou). And it is not talking about the creation of the whole physical universe but the creation of man -- it was God's purpose in creating man. The agency belongs to God ("he created the world"), not the parents of first human children. Also Abel was not "the start of the human family", that distinction belongs to Cain. The mention of Abel in Luke 11:49-51 is that his was the first blood slain "since the founding of the world" -- not that the founding of the world began somehow with him (Abel had no children, hence the family begins anew in Genesis 5 with Seth). As an aside, I wonder if the use of the expression apo/pro katabolés kosmou in the NT is due to influence from the Assumption of Moses. This is a very rare expression and it seems too coincidental that it has reference to divine foreordination in both the Assumption of Moses and the NT. We know from Jude 9 that the Assumption of Moses had an influence elsewhere on the NT. Since Jesus takes over the role as mediator in the NT (1 Timothy 2:5, Hebrews 8:6, 9:15, 12:24), the transferral of the role as the preordained mediator from Moses to Jesus makes a lot of sense.
Also I still do not see how placing the "founding of the world" after the "fall" is supposed to preclude individual predestination. Even if we suppose this in the case of the Assumption of Moses, we still have Moses predestined to be the mediator of the covenant ages before he is born. The same goes with the people who will worship the Beast in Revelation -- from the founding of the world their names were not written in the book of life, even though they would be around until the ending of the world.
Anyway, interesting and stimulating discussion!